Using experimental and manufacturer data, the maximum ...



List of Figures 3

List of Tables 3

Abstract 4

Background/Problem Statement 5

Objectives 5

Project Deliverables 5

VECHILE DYNAMICS 6

Objectives 6

Platform Selection 7

Considerations: 7

Options: 8

Decision: 11

Loading/Unloading of the e-Zapper 12

Considerations: 12

Options: 13

Decision: 13

Trailer Requirements 14

Items to be Purchased 19

Need to be engineered 19

POWER GENERATION 21

Electric Schematic 21

Power Requirements 22

Generator Selection: 23

Generator Testing: 24

HEAT TRANSFER 25

Cooling System 27

Chiller Selection 29

Pumps 30

RADIOLOGICAL CONTROLS 31

Experimental Calculations 31

Beam stop 34

Program Management 37

Work Breakdown Schedule 37

Vehicle Dynamics 37

Power Generation 38

Heat Transfer and Radiation 38

Budget 39

Conclusion and Recommendations 39

List of Figures

Figure 1- Model of e-Zapper being loaded via the ramp system 7

Figure 2-Conventional Trailer 10

Figure 3- 5 Ton Military Truck 11

Figure 4- Refrigerated Truck 12

Figure 5-Gooseneck Trailer 16

Figure 6-e-Zapper Weight Distributions 17

Figure 7- Center of Gravity for e-Zapper 18

Figure 8- Moment Diagram for Trailer Interior 18

Figure 9- Final Layout (Inside Trailer) 19

Figure 10- Front End Support (Loads and Restraints) 21

Figure 11- Displacement of Support (scale in meters) 21

Figure 12- Factor of Safety for Support 22

Figure 13- Electric Schematic of the e-Zapper 23

Figure 14- Selected Generator (Shown without sound enclosure) 26

Figure 15- Heat Removal Requirements When System Operated as Open System 28

Figure 16- e-Zapper Cooling System 29

Figure 17- Experiment Schematic of Concentric Iron Pipes 33

Figure 18- Experimentally Determined Radiation Map 34

Figure 19- Iron Pipes with Dosimeters 35

Figure 20-Various Calculated Ranges of e-Zapper Radiation (Assuming no shielding, beam energy of 6 MeV, beam current of 5 mAmps, and constant high fire mode) 37

List of Tables

Table 1- Component Weight and Dimensions 9

Table 2- Weighted Vehicle Selection Options 13

Table 3- Loading/Unloading Selection Matrix 15

Table 4- Current Drawn by e-Zapper 24

Table 5- Initial Generator Options 25

Table 6- Experimental Current Requirements using the Caterpillar XQ30 Generator 25

Table 7- Final Generator Selection Comparison Matrix 26

Table 8- Heat Removal by Water from e-Zapper Under Different Operating Conditions 27

Table 9-Chiller Vendors 31

Table 10- Weight Factors for Chiller Selection 31

Abstract:

The e-Zapper project involves the design of a mobile platform which will be able to transport and operate a linear accelerator that produces high energy electrons with the ability to disarm Improvised Explosive Devices. The project is divided into three sub-teams: vehicle dynamics, power generation, and radiation and heat transfer. This report contains concepts developed by each to address their specific challenges.

The vehicle dynamics team has evaluated potential platforms for stabilizing the linear accelerator minimizing vibration and the effects of the natural frequency. They have also selected a Pace American trailer platform to be modified used to transport the e-Zapper. Other design considerations include a ramp and required components to load the e-Zapper onto the truck and a front end support to make the system mobile.

The power generation team has developed an electric schematic of the system. Field tests of potential generators have been used to solidify the requirements of a generator to operate the e-Zapper. The final recommended generator is the Baldor IDLC-30-JD.

The heat transfer and radiation team has done calculations involving the radiation doses emitted by the e-Zapper. Experiments have been done to determine the radiation forward, sideways, and behind the system. Analysis has also been done on the cooling requirements of the system and the Cold Shot ACWC-60-E chiller has been recommended.

Background/Problem Statement: Since the outbreak of the War on Terror in Iraq the number of deaths due to Improvised Explosive Devices (IED) has increased by 2500%. According to IEDs account for over 40% of all US fatalities in Iraq. Terrorists are becoming increasingly proficient in fabricating IEDs as the war continues. The reason for this is the widespread availability of Radio Frequency (RF) switches which allow precise timing for detonation.

In 2006, the Office of Naval Research budgeted over 3.3 billion dollars to be spent on IED countermeasure research. Current countermeasures include Bradley Fighting Vehicles fitted with RF jamming capabilities. This is an indiscriminate countermeasure that requires jamming all RF frequencies, and thus it interferes with any military communications.

The e-zapper team has been tasked with designing a platform capable of transporting the e-Zapper. The e-zapper is a modified linear accelerator currently capable of disabling IEDs from 30 feet without detonating them. It works using a low energy beam to destroy the RF transmitter used to detonate IEDs. It is currently being developed and tested at Technical Options Inc in Newark, Ohio. This year’s team was responsible for designing a mobile system to allow the e-zapper to be tested while keeping the operators safe from potential radiological threats. This included testing to determine the radiological threats, power requirements, and evaluation of potential platforms. It is planned to transport the system from Ohio to Naval Surface Warfare Center Indian Head (NSWC-IH) for further testing by an explosive ordinance disposal unit in FY2008.

Objectives:

The objective of the e-Zapper team is to design a platform capable of transporting, testing, and eventually operating the e-Zapper in a experimental environment. The team must create a design that can be presented to the Office of Naval Research and could be fabricated as a project following 1MAY07. The main considerations in the design process are Vehicle Dynamics, Power Generation, Heat Transfer, and Radiation.

The objective of the Vehicle Dynamics team was to choose a platform capable of supporting the e-Zapper and then designing a system to load the e-Zapper onto that platform. The Power Generation team was responsible for mapping the layout of the e-Zapper electronics and determining the power load of the operational machine. The team then selected a generator capable of supporting the calculated power load. The radiation and heat transfer team was responsible for determining the heat load of the e-zapper and choosing a chiller system. This team also conducted experiments on the radiological map of the e-Zapper and then used experimental data and theoretical calculations to create radiation maps around the system.

Project Deliverables:

• Choose a platform capable of transporting the linear accelerator and supporting equipment

• Design a system capable of lowering the e-Zapper in and out of the selected platform

• Choose a generator capable of running the linear accelerator and supporting equipment

• Map out the electronics system of the necessary elements and remove unnecessary parts and wires

• Create a radiation map to be used in project testing both in the lab in Newark, Ohio and in NSWC Indian Head

• Choose a suitable chiller system if one is determined to be needed.

Concept Designs:

VECHILE DYNAMICS

[pic]

Figure 1- Model of e-Zapper being loaded via the ramp system

1 Objectives

At the beginning of the year the vehicle dynamics team was tasked with complete mobilization and construction of a system to move the e-Zapper system to NSWC-IH Testing Grounds. During the course of the year there were many different design changes resulting from lack of information and specifics of the system itself. Hence, at the start of the second semester the vehicle dynamics team restarted. First, the weight and dimensions of several different components which were previously unknown were found. Next, those dimensions were used to make minimum design requirements. Due to the greatly reduced timeframe, the objective became developing a viable solution for the transport of the e-Zapper. This involved selecting a platform to transport the machine, finding a way to unload/load the e-Zapper for maintenance, creating a list of recommended purchases in order to mobilize the system in the upcoming year, and lastly a list of recommended procedures for transporting the e-Zapper. Figure 1 shows a SolidWorks model of the eventual goal of loading the e-Zapper into a trailer via the selected ramp system.

2 Platform Selection

1 Considerations:

1. Weight Requirement: The e-Zapper system’s weight is nearly 15,000 lbs.

2. Storage: The e-Zapper needs to be stored in a readily accessible location for students and faculty to be able to work on it. Additionally, the climate concerns need to be taken into consideration (i.e. there will need to be heating/cooling systems to protect the electronics).

3. Accessibility: As the e-Zapper is a prototype, it will require constant modification and tuning. For this reason it is vital that there remains sufficient room for engineers/technicians/midshipmen to work on the weapons system. Also, each component should, in itself, be well laid out for adjustment and maintenance.

4. Isolation: The e-Zapper is made from an RF-accelerator that was designed for stationary use as radiation therapy. Hence, it was not designed for use in a mobile environment that would be subjected to vibrations from the road. Therefore, it is essential to isolate those systems that are identified as most sensitive to G-loading. Steve Andrews, of Technical Options, the e-Zapper team’s expert on the RF-accelerators, identified the most sensitive component as the filament for the Klystron. It is vital then that this component be isolated from transmitted shock. In other words, the platform must have a suspension capable of not only handling the weight but absorbing moderate shock.

5. Radiation Shielding: The e-Zapper produces a significant amount of radiation, so much that it is necessary to protect the operators of the unit from the effects. Although most of the radiation that exits the unit comes out of the front of the tube, there is still substantial emission to the rear of the system (as shown in the radiation section of the report). Consequently, shielding will need to be erected to protect those operating the system, which should be done behind the weapon, likely in a different room, accessible from the outside. With the addition of most likely lead radiation shielding the overall weight of the system will increase a considerable amount.

6. Cable Routing: The e-Zapper requires a considerable amount of linking cables (an estimated 400 lbs). As a result, it will be necessary to develop a means of channeling the cable in a way that is efficient and provides ready access. Proposed solutions are a false floor in the weapons system area were the cable will be routed underneath or a series of ducts and channels that will contain the cable. The best solution providing the most ready access would be the false floor; however, there will be some problems when dealing with the mounting of some of the electronics. Simple ground conduit would be the most probable solution.

7. Physical Dimensions: Table 1 is a listing of the physical dimensions and approximate weights of the components of the e-Zapper. The actual total weight was determined by weighing the e-Zapper with 4 McMaster-Carr 5000 pound capacity load cells.

|Component |weight (lb.) |Dimensions (in) |

|Electron Accelerator |  |  |

|Electron Source Controler (esc) |2200 |48 x 80 x 30 |

|Klystron |330 |See solenoid |

|Focusing Solenoid |600 |D=16 h=18 |

|RF Pulse Transformer |1800 |38x30.5x14 |

|Kylstron Power supply |300 |  |

|RF Driver |80 |19x17x4 |

|RF Pulse Forming Network |Part of ESC |  |

|Accelerator Solenoid Power Sup. |300 |18x7x21 |

|Output Rotary Flange |25 |d=4.5 l=6 |

|Rotary Flange Motor |10 |6 x 6 x 6 |

|Vacuum Ion Pump |85 |D= 8.5 L =12 |

|Ion Pump Controler |25 |19 x 12.5 x 7 |

|Ion Pump Power Supply |25 |18 x 7 x 21 |

|VAT High Speed Valve |5 |  |

|VAT High Speed Controler |10 |19 x 15 x 5 |

|Circulator |80 |31 x 16 x 7.5 |

|Gas Bottle |38 |h= 23 d=6 |

|Wire |400 |  |

|Heat Exchanger/Water Tank |280 |15 x 14 x 50 |

|Zapper Controler |50 |30 x 9 x 17 |

|Monitor Panel for Controler |20 |17 x 7 x 7 |

|Vacuum Turbo pump |5 |20 x 7 x 5.5 |

Table 1- Component Weight and Dimensions

2 Options:

1) Conventional Trailer

[pic]

Figure 2-Conventional Trailer [1]

The use of a trailer presents several benefits. First, by being able to tow the equipment behind a vehicle such as a simple truck with a hauling capacity of 10 tons would be easier to obtain than most any other platform. Additionally, the size concern disappears, as there are several sizes of trailers that could be selected from. The trailer shown in Figure 2 is from Pace American and can be ordered in a multitude of sizes and specifications. The weight is not a limiting factor as there are many trailers that are able to be customized to handle the weight and suspension requirements of the system. Also, the trailer may be towed by a conventional heavy-duty pickup that would not require a commercial driver’s license and could be rented even. Additionally another advantage is the low cost of the trailer at approximately $25,000. The disadvantage of using a trailer is that it requires a separate platform to tow it and there is no military compatibility.

2) 5 Ton Military Truck (M939) [pic]

Figure 3- 5 Ton Military Truck[2]

This option provides several obvious benefits. First, the size and loading capabilities of this platform are more than advantageous for the purposes of the mobilization of the e-Zapper. The ideal vehicle would be the M939 with a hard top van design so as to avoid having to fabricate an outer shell. The engine used is the Cummins NHC 250, producing 250 hp. The platform clearly states that it can hold five tons in the bed itself, as well as tow 20,000 lbs. in the rear. The disadvantages of this platform rest heavily on the suspension the vehicle currently uses, the fact that the e-Zapper would have to be modified for a low ceiling, and that all the system components could not fit in the bed because of both dimension size and weight. The advantage of this platform is its ability to carry most of the components in a single platform and that this truck is in heavy use with the military and has wide availability. A soft top version of this platform is shown in Figure 3 (above).

3) Refrigerated Delivery Truck

[pic]

Figure 4- Refrigerated Truck[3]

This platform presents a very valuable feature that the previous two platforms have not; the cooling system. With an air cooled cargo area, the need for a heat exchanger or the installation of an air conditioning system goes away as the option already has one installed. Additionally, the space requirements are easily met, as this platform is more than large enough. Moreover, the suspension of the vehicle is adequate to transport the system over paved/improved roads. As with each of the other platforms, compartmentalization would need to be done. The main disadvantage with this option is the lack of customization available by the manufacturer and the lack of military compatibility. On the other hand, these trucks can be purchased used for a relatively low cost (~$50,000) and are fairly easy to come by.

3 Decision:

Table 2 shows the decision matrix used to evaluate the three vehicle choices.

|Vehicle Selection Options |

|  |Cost |Availability |Maintenance |Weight |Space |Highway |Military |Ease of |Total |

| | | | |Capacity |Available |Capable |Compatiblity |Operation |Points For|

|Factor (Take times|5 |5 |5 |9 |9 |7 |3 |8 |  |

|Vehicle Values) | | | | | | | | | |

|5 Ton Truck |4 |4 |5 |7 |6 |3 |8 |4 |259 |

|Trailer |6 |6 |3 |9 |9 |7 |5 |8 |365 |

|Refrigerated Truck|5 |5 |3 |9 |9 |6 |5 |5 |324 |

| | | | | | | | | | |

| | | | | | | | | | |

| | | | | | | | | | |

|Values Explanation|Range | | | | | | | | |

|Assigned Vehicle |1 to 9 |1: Low |9: High | | | | | | |

|Values | |Performance |Performance | | | | | | |

|Factor |1 to 9 |1: Low |9: High | | | | | | |

| | |Importance |Importance | | | | | | |

Table 2- Weighted Vehicle Selection Options

The platform selected was the conventional trailer. This platform will meet all of requirements put forth already. The triple axle version is capable of supporting the load that will be placed on inner surface. The torsion spring suspension used by the trailer will successfully dampen the vibrations, reducing the shock the electronic components experience.

3 Loading/Unloading of the e-Zapper

1 Considerations:

1. Weight: The system needs to be highly portable so that it can be loaded and stored in the trailer.

2. Ease of operation: Requires a minimum amount of set up time, as well as a minimum amount of operators. The more simple the procedure is, the better because then anyone can load or unload it with minimal training.

3. Strength: Needs to be strong enough to handle the near 10,000 pounds that will be moved onto and off of the trailer.

4. Motion: Moving the e-Zapper onto and off of the trailer needs to be precise, as it will have a designated space within the trailer where it is secured.

5. Self Containment: The system needs to be portable with the ability to be loaded onto the trailer so loading and unloading can occur at any location that has a concrete or asphalt surface. This means that the equipment will need to be light enough to be moved by a person and small enough to store on the trailer itself.

6. Cost: The system needs to not be overly expensive.

2 Options:

1. 16 foot ramp/roller track system: this system uses two ramps, which are both sixteen feet in length. The load capacity of these ramps is 40,000 pounds. Each side of the ramp is divided into two equal eight foot segments. The weight of the ramp sections are eighty pounds, easily moved by two people. Also, the ramps are a cheaper solution than the other two. The downsides to this will be the having to winch the e-Zapper up the ramps and also the concern that the e-Zapper will experience a strong point load at the entrance of the trailer as it is winched up.

2. Hydraulic lift: this option consists of the lifting the e-Zapper vertically before moving it into the trailer. Once at the proper height it would be winched into the trailer along a fabricated track system. The issue with this becomes finding hydraulic lifts sturdy enough to lift the e-Zapper vertically. Secondly, the level of precision that is necessary while raising the e-Zapper would be incredibly high, and since this system is manually operated that is not feasible.

3. Tilting the trailer: This process involves raising the forward end of the trailer at such an angle where the e-Zapper could be winched into the trailer using a fabricated track system. Once in the trailer, the winch would hold the e-Zapper in place as well as the securing system. Raising the front end would be achieved by using jack stands. The problem with this option is that is requires a lot of moving parts and it is not very safe.

3 Decision:

The final decision was to go with the ramp system. As seen on the following decision matrix in Table 3, the ramp system is the most viable option. Because the ramps are affordable, portable, safer, and more user friendly; they were the selected method.

|Loading/Unloading of the e-Zapper, Options |

|  |Cost |Availability |Maintenance |Weight Capacity |Safety |System Weight |Total Points |

| | | | | | | |For |

|Factor (Take times |3 |5 |5 |9 |9 |5 |  |

|Vehicle Values) | | | | | | | |

|16 Foot Ramp, |5 |3 |9 |9 |9 |9 |282 |

|Caster/Track System | | | | | | | |

|Hydraulic Lift |3 |5 |4 |2 |7 |1 |140 |

|Tilting of the Trailer |5 |5 |2 |2 |2 |8 |126 |

| | | | | | | | |

| | | | | | | | |

| | | | | | | | |

| | | | | | | | |

| | | | | | | | |

| | | | | | | | |

| | | | | | | | |

|Values Explanation |Range | | | | | | |

|Assigned Vehicle Values |1-9 |1: Low |9: High | | | | |

| | |Performance |Performance | | | | |

|Factor |1-9 |1: Low |9: High | | | | |

| | |Importance |Importance | | | | |

Table 3- Loading/Unloading Selection Matrix

4 Trailer Requirements

1. Trailer: The trailer needs to have an interior height of 110 inches and a width of 8.5 feet. There needs to be at least three 7200 pound axles. To support the high pressure there will need to be reinforced floors. In order to protect the sensitive electronics there will need to be a strong torsion spring suspension. The overall length of this trailer will need to be in excess of 44 feet. Other customizations from the factory are an air conditioning unit, exhaust ports, small generator for extraneous control system equipment and the winch, and an access door at the front of the trailer. The Trailer will be a Pace American trailer with the aforementioned modifications. A standard gooseneck trailer is shown in Figure 5. The final decision on the exact trailer will be made by USNA with the input of Steve Andrews of Technical Options and the Office of Naval Research. According to Mr. Andrews, a separate system to prevent vibrations, in addition to options available on the trailer, should not be necessary since the e-Zapper is currently transported via tractor trailer and will never be fired while in motion.

[pic]

Figure 5-Gooseneck Trailer

2. Wheels/roller/track requirements: Weight bearing capacity of each wheel/roller should be at least 5000lbs each. The system will be moved over concrete and asphalt, so the weight will have to be distributed over a large enough area so as not to crush the concrete or asphalt. The track will need to be in precise construction and alignment in order to prevent binding and crimping in the track. A tolerance of less than 1/16” between the two tracks is recommended.

3. Winch requirements: Capacity of the winch should be 10,000lbs in order to ensure that the e-Zapper will be towed up the ramp without issue. The winch must have a reverse tension feature for unloading the e-Zapper so that it does not slide down the ramp with reckless abandon.

4. Ramp requirements: The ramp needs to be high strength but portable so that it may be stored in the trailer when it is not being used. Sections weighing less than 100 pounds each are recommended.

5. Layout Requirements: When placing the components within the trailer, the centers of gravity and the moments created by the acting forces need to be taken into consideration when placing certain items. The current weight distribution is shown in Figure 6. The following calculations in Figure 7 and Figure 8 are weight distribution calculations that show a viable layout scheme.

Figure 9 shows the final layout recommendation. An Engineering Equation Solver (EES) program file is enclosed on the compact disk accompanying the report, which allows for the easy changing of the different possible layout position schemes.

[pic]

Figure 6-e-Zapper Weight Distributions

Total e-Zapper Weight=7550+2320 lbs

Total e-Zapper Weight =9870 lbs

[pic]

Figure 7- Center of Gravity for e-Zapper

[pic]Figure 8- Moment Diagram for Trailer Interior

[pic]

Figure 9- Final Layout (Inside Trailer)

1 Items to be Purchased

The following is a list of items that have been selected by the Vehicle dynamics team but need to be purchased and tested by a future e-Zapper team.

1. Trailer to specification

a. Available by a variety of custom trailer manufacturers

b. Example by Pace American is the SCXG8544TTA5K ( it is only a base example and will need to be customized)

2. Ramp

a. Available in our specifications by one single manufacturer

b. Landsport 16 foot two-section ramp ()

3. Rollers

a. Available in our specification by one single manufacturer

b. McMaster 5000lb Capacity Roller (Part No. 2736T22, catalog page 1230)

4. Jack Stands (for trailer support when loading/unloading/no_e-Zapper situations)

a. Available in our specifications by multiple manufacturers

b. Example by 6-ton jack-stands ()

5. Jack (for use with jack stands)

a. Available in our specifications by multiple manufacturers

b. Example by ’s 15 ton floor jack Part No. JM-5015, ()

6. Winch

a. Available in our specifications by multiple manufacturers

b. Example by ’s PS10000 Electric Winch, ()

2 Need to be engineered

1. Front support: The e-Zapper as it is now has four ideal locations to mount rollers on to the existing frame in the rear. These locations will be used as the baseline in terms of width. This width is 45 inches. A front end support will need to be added to support the front end of the e-Zapper and also provide a place to mount a set of rollers. The width becomes an issue because there is only one good spot to mount a support and at this point the width is narrower than 45 inches. Thus there is a need to design a front end support to adequately meet the width and weight requirements. The following SolidWorks files, Figure 10, Figure 11, and Figure 12, are a single solution to the problem. It is a two force member which as the finite element analysis shows will easily handle the weight being exerted on the support structure. The SolidWorks files are enclosed on the accompanying compact disk.

[pic]

Figure 10- Front End Support (Loads and Restraints)

[pic]

Figure 11- Displacement of Support (scale in meters)

[pic]

Figure 12- Factor of Safety for Support

2. U-track system to transport e-Zapper up track using rollers: When loading and unloading the e-Zapper from the trailer, a track system will be necessary to keep the e-Zapper properly aligned so it will stay on the ramp and also so it can be guided into its proper position within the trailer. The tolerance for the precision of the track is suggested to be within 1/16 of an inch so as to ensure it does not derail and cause the track itself to crimp under the heavy weight the e-Zapper will exert. Further specific designs on this system will be completed by a future e-Zapper team.

POWER GENERATION

The power generation team must determine the electric schematic of the parts required for the e-Zapper to function. It is then responsible for researching, testing, and selecting a generator capable of supporting the e-Zapper power load. The team is also responsible for aiding the vehicle dynamics team with trailer selection and layout based on the requirements of the electrical systems within the e-Zapper.

Electric Schematic

After a close and detailed study of the electrical layout of the machine provided by book of drawings that comes with the Varian 1800 electron accelerator, a detailed schematic of the stripped down machine are included in this report. Many things were removed from the Varian ClinAc 1800 electrical schematic such as the patient table, magnet, gantry motor, and all of the components that go along with it as well. The schematic has been verified by a visit to the site and by Steve Andrews of Technical options and is show in Figure 13.

[pic]

Figure 13- Electric Schematic of the e-Zapper

Power Requirements

The power drawn by the e-Zapper in its four functional modes is shown in Table 4. Line A, B, and C represent each of the 3 phases of the AC power requirements.

|e-Zapper Status* |Line A |Line B |Line C |

|Quiescent Current |8 A |9 A |6 A |

|Warm-Up (10 min.) |32 A | 30 A |31 A |

|Firing Mode |70 A |70 A |69 A |

|(Low Power) | | | |

|Firing Mode |90 A |91 A |89 A |

|(High Power) | | | |

|Maximum Power Drawn(BTU/hr) |110630 |111859 |109401 |

Table 4- Current Drawn by e-Zapper

Using experimental and manufacturer data, the maximum current drawn by the e-zapper machine was determined to be 91 Amps in line B during the high power firing. The voltage supplied to the power cabinet is required to be 208 3 phase AC power. The power required was calculated using Equation (1).

[pic] (1)

Where V is voltage in volts, I is current in amps, and P is power in kW.

The maximum power requirement is 32.8kW, and it occurs in Line B in the maximum power mode.

Generator Selection:

It was decided the generator should be diesel in order to be most compatible with current military operations. The other key elements in the selection process include the power output in kW, the maximum number of amps that can be produced, and if the generator is mobile. The generator may also need to be towed behind the trailer for space or heat requirements. A comparison of the 5 initial generator options is show in Table 5.

|Name |Vendor |Max Amps |Hz |kW |kVA |Mobile |Cost |

| | | | | | |(Y\N) | |

|Baldor TS60T |Curtis Engine |155 |60 |48 |60 |Y |$ 23,177 |

|J40UC |Bowers |128 |60 |37 |46 |N |$10532 +Freight |

| |Power | | | | | | |

|Baldor TS45T |Diesel Generator |121 |60 |37 |46 |Y |$20588.00 |

| |Pro | | | | | | |

|Baldor TS35T |Curtis Engine |91.6 |60 |30 |37 |Y |$ 17,950 |

|Baldor TS35T |Diesel Generator |91.6 |60 |30 |37 |Y |$18,253 |

| |Pro | | | | | | |

Table 5- Initial Generator Options

The decision was made by the Power Generation and Vehicle Dynamics groups to purchase a trailer capable of holding the generator thus eliminating the need for a wheel mounted generator.

Generator Testing:

Generator tests were run this semester to ensure the accuracy of the calculations. Based on availability in Newark, Ohio, Caterpillar generators were used for the test. They were the only ones available that operated at 60 Hertz. The Cat XQ30 generator was determined to be the best option. In addition to fulfilling the power requirements, it comes encased with insulation to help reduce noise and reduce heat. The test also highlighted the need for adequate ventilation in the generator compartment. The currents measured in each line with the XQ30 are shown in Table 6.

|(Measured in amps) |Line A |Line B |Line C |

|Standby Mode |45 |40 |42 |

|Firing Mode |85 |81 |81 |

Table 6- Experimental Current Requirements using the Caterpillar XQ30 Generator

The maximum amperage the generator can deliver is 110A.

The original selection of generators was deemed inadequate after the generator testing. It was determined that the generator needed sound enclosure, an electric governor, and only 30 kW. It was also determined that a mobile generator was no longer needed. The final selected generator comes from the Baldor Generators Company. The unit selected is a 30 kW, 3-phase generator that has voltage of 208V in the Low-Wye configuration. This generator was selected out of many others for its features, options, reliability, and cost. The unit comes with a variety of options that are necessary to make this project a success. First, an electric governor is an available option with this generator. This is important because the e-Zapper is a sensitive piece of equipment electrically and the electric governor provides for tighter tolerances in voltage and current. The unit also has available sound attenuation at different levels. Level II sound isolation will reduce the sound to 68-70dB at 7 meters. At this level hearing protection will not be required to operate the machine which is a necessity because operators will be in close range to the generator.

This unit was also the least expensive. Generator Joe, which is a large generator distributor, has quoted a price of just around $10,200 plus shipping and handling. This number is thousands less than the nearest competitor generator and was the only one with an electric governor. This unit, new, also come with a 1 year or 3000 hour warranty, whichever comes first. Since it is an American made generator, it should be relatively easy to locate a repair facility should problems arise. Table 7 contains the comparison matrix for the final generator choices.

|Vendors |Sound Enclosed |Price |Electric Governor |Warranty |

|Caterpillar |9 |5 |0 |6 |

|Baldor |8 |9 |9 |6 |

|IDLC-30-JD | | | | |

|Cummins |8 |0 |0 |6 |

|Kohler |8 |6 |0 |6 |

Table 7- Final Generator Selection Comparison Matrix

[pic]

Figure 14- Selected Generator (Shown without sound enclosure)

HEAT TRANSFER

For this project, it is known that heat will be generated by the required equipment. Adequate cooling is essential to the operation of the e-Zapper. The electron accelerator is known to generate a considerable amount of heat; however, the exact amount has been experimentally investigated, as shown in Table 8. Currently, an open loop cooling system is in operation cooling the equipment. The current open loop water heat removal is shown in Figure 15 with theoretically derived estimates for heat generation by the e-Zapper. Figure 14 also demonstrates the approximate amount of heat that ambient air surrounding the machinery of the e-Zapper needs to remove.

Based on the requirements for the exit window, a standard operating procedure (SOP) was written, which states that the machine may not be operated in firing high mode for more than six minutes per every hour, which far exceeds current operating limits based on the material limitations of the Beryllium window. If six minutes of firing per hour were performed, the window would fail. By writing the SOP in a highly conservative manner, a factor of safety of at least 2 is inherently included in calculations. The rest of the time, the machine must remain in warm-up mode. Using this procedure and the electrical power loads for the various firing modes, the maximum total heat generated was calculated to be 45,400 BTU/hr. Subtracting the heat removed by natural convection would then yield the heat needed to be removed by the chiller.

|e-Zapper Status* |Output Temperature |Flow Rate |Flow Rate |Heat Removal by |

| | | | |Water |

| | | | |[BTU/HR] |

|Quiescent Current |N/A |0 |0 |N/A |

|Warm-Up (10 min.) |97 F |1.7 gal/min |1.1 |60 |

| | | |liter/sec | |

|Firing Mode |N/A |N/A |N/A |N/A |

|(Low Power) | | | | |

|Firing Mode |98 F |3.3 gal/min |2.1 |115 |

|(High Power) | | |liter/sec | |

Table 8- Heat Removal by Water from e-Zapper Under Different Operating Conditions

[pic]

Figure 15- Heat Removal Requirements When System Operated as Open System

Cooling System

Given the need for mobilization, a closed loop cooling system has been designed and developed. Additionally, any heat load generated by support equipment requires excessive waste heat to be removed. This can be achieved by using both air-cooling or water-cooling. From this information, initial design concepts and possibilities were produced for a heat transfer system. A basic schematic of the cooling system is shown in Figure 15, which shows a basic schematic of the closed loop cooling system required for a mobilized e-Zapper. A heat exchanger is required in order to act as a heat sink for waste heat from the cooling medium to dump heat. A pump is required in order to generate flow through the system.

[pic]

[pic]

Figure 16- e-Zapper Cooling System

Before designing a cooling system and selecting chiller vendors, the total heat load generated from the e-Zapper needed to be determined. Electrical current loads were experimentally measured from a team visit to the project site. Table 4 shows the electrical loads for various firing modes on each line of the 3 phase AC line used to power the machinery.

For each mode, the current was averaged over the three lines. Power generated from the machinery was calculated using Equation 1. Voltage was assumed to be 208 V. Total electrical power equals the maximum heat load that the machine can possibly generate.

During the design process, heat loss to both the coolant in the cooling system and the ambient air needed to be taken into consideration. Cooling from the ambient air was a minor factor that needed to be calculated. Natural convection figures were calculated using equations (9.26 or 9.27 from pg. 507) taken from Incropera and Dewitt’s Introduction to Heat Transfer: 4th Edition, with the main governing equation being equation 2.

[pic] (2)

Where Q is the natural convection from the e-Zapper in Watts, h is the natural heat convection coefficient in W/(m2*k), A is the area in m2, and T is the temperature in Kelvin. After finding final figures, heat transfer figures were converted to BTU/hr. The following assumptions were made in calculating losses to natural convection:

1. Ambient air temperature was assumed to be 70 F.

2. All components were assumed to be of uniform temperature.

3. All components were assumed to be of the same surface temperature as the hottest component, which was measured to be 110 F.

4. All components were treated as vertical plates.

5. Representative area of all the components was 5.5 m2.

Based upon calculations, approximately 1600 BTU/hr were able to be removed via natural convection. Taking the maximum total heat generated and subtracting 1600 BTU/hr yielded a necessary cooling capacity for the chiller of 43,800 BTU/hr. With this cooling capacity in mind, several different avenues of chilling the e-Zapper were explored.

Chiller Selection

The possibility of cooling the machinery with a tank of constantly recirculating water was first investigated. Estimations of the quantity of water required to cool the machinery and not utilize an additional heat exchanger was set at 100 gallons. However, this concept encountered some basic problems early on its design process. First, weight considerations had to be taken into effect in the design of the e-Zapper cooling system. At approximately 8.34 pounds per gallon of water, the system would weigh over 800 lbs. When comparing this weight to the weight of the chiller candidates, the 100 gallon tank is heaviest of all, weighing almost 100 lbs more than the heaviest chiller.

Examination of solutions to this weight problem indicated other alternatives were available: the coolant could be drained before moving the e-Zapper. This solution solves the problem of transporting the heavy load of the coolant/cooling system, however, this solution also proves to be impractical and uneconomical.

It was decided that the e-Zapper should have a coolant mixture of 50% water and 50% ethylene glycol in order for the cooling system to withstand freezing temperatures, as these could be a factor while testing at NSWC Indian Head. Transport of 50 gallons of ethylene glycol to fill on site would prove to be more weight and troublesome than a conventional chiller. Also, considering future possible applications in the desert, adding 100 gallons of water at each location the system is used would prove to be more impractical than a conventional chiller.

The search for chiller vendors yielded three vendors and models as shown in Table 9. Table 9 shows each vendor’s specific dimensions, weight, cooling capacity with water and water/ethylene glycol mix, electrical load, and cost. Table 10 shows the weighting factors used to compare the chillers. Five important primary factors were considered in the chiller selection process: cost, size, weight, electrical load, and cooling capacity. Each individual factor was weighed according to its importance to the mission of this year’s team. As shown, cooling capacity was the most important and heavily weighed factor with size and weight next in the pecking order.

From the criteria given, the chiller provided by Cold Shot Chillers showed to be the best choice overall. It should be noted that it is uncertain at this point if there is enough time before the conclusion of this project to be able to purchase the chiller, but if so, the Cold Shot chiller would be the first choice. Another plus of the Cold Shot over the General Air Product chiller was that the Cold Shot chiller possessed a reservoir for cooling medium, allowing for easy access for recharging of the cooling system. This reservoir also provides a head pressure for the eye of a centrifugal pump, preventing pump cavitation.

|Vendor |Model |Dimensions [in] |Weight [lbs]|Capacity [kW] |Cap (50/50 gly/wat) |Electric Load |Cost [$] |

| | | | | |[kW] |[V] | |

|Liebert |PS096A |77x69.25x38.5 |750 |25.2 |21 |230 |15,490 |

|General Air |050 |29.3x53.1x42.9 |473 |16.7 |13.92 |460 |8052 |

|Products | | | | | | | |

|Cold Shot Chillers|ACWC-60-E |32x43x60 |500 |17.58 |14.65 |460 |6465 |

Table 9-Chiller Vendors

|Vendor |Cost |Dimensions |Weight |Electrical Load |Cooling Capacity |Total |

|Liebert |2 |1 |1 |9 |9 |4.65 |

|General Air Products |5 |9 |9 |6 |2 |5.2 |

|Cold Shot Chillers |8 |7 |7 |6 |6 |6.3 |

|Weight of Each Factor |.5 |1 |1 |.25 |2 | |

Table 10- Weight Factors for Chiller Selection

Note: For chillers: 9=best, 1=worst.

For weighing factors: higher number signifies more important.

Pumps

Basic considerations were made for pump requirements for the cooling system. In order to overcome all headloss in the tubing, chiller isolation valves, and the pressure drop across the e-Zapper and heat exchanger, a minimum of 11 psi of pump head was needed. A minimum flow rate of 3.3 GPM was required to cool the system adequately in high firing mode as shown in Table 7. Two basic pump types were considered in the design process: positive displacement and centrifugal. Positive displacement pumps need no head pressure, but require more energy and are more difficult to maintain than their centrifugal counterparts. Centrifugal pumps cost less and are lighter also. Since centrifugal pumps possess are easier to maintain, cost less, use less energy, and weigh less than a positive displacement unit, use of that type of pump was optimal. The chiller chosen from Cold Shot Chillers provided a centrifugal pump with a pump pressure of 30 psi and a flow rate of 30 GPM, more than enough to fit the minimum pump requirements of the system. Transporting the cooling medium would be accomplished by the use of polypropylene tubing, the same as the current cooling system is currently using. In order to fit onto the fittings of the selected chiller, a 0.75 inch inside diameter fitting would need to be used to attach to the 1 inch inside diameter tube. Since polypropylene tubing is highly chemical resistant, making it a wise choice if using a mixture of water and ethylene glycol. The tubing is rated at 100-250 psi operating pressure and 101-200 F operating temperature, well within safe bounds of the current operating conditions.

.

RADIOLOGICAL CONTROLS

Experimental Calculations

The e-Zapper is a 18 MeV electron accelerator. Its parts are derived from hospital radiation therapy machinery. X-ray, beta, and gamma radiation are a major concern for operators of the e-Zapper. Shielding against such radiation will have to be in the form of a dense material, such as lead, to absorb the high energy radiation. One of the major accomplishments of the team was to perform an experiment that involved two sets of 45 TLD’s, which are very accurate radiation detectors. Unfortunately, due to problems beyond the team’s control, the e-Zapper was not operational for several months. Because of this delay, it is unlikely that it will be possible to design adequate shielding for the e-Zapper. However, using the data from the experiment, it was possible to create a two dimensional chart of the radiation field.

Calculations of the radiation field in the forward direction were made based on the following assumptions:

(1) Electron beam energy of 6 MeV

(2) Beam current equal to 5 microAmps

(3) Electron stopping power (dE/dx) were taken directly from the NIST/EStar database[4]

(4) Air density was assumed to be 1.23E-3 g/cm3

(5) Electron energy loss in air was 0.236 MeV/m [5]

(6) The half-angle of beam spreading was 7.5 degrees

The radiation field was calculated in one foot increments. For every foot of travel, the electron beam dilutes in strength by spreading across a wider area and increasing bremstrahlung and x-ray production. Following standard radiological operating procedures listed in the National Council on Radiation Protection and Measuremetns (NCRP) 144, a radiation exclusion zone with a 2 mrem/hr boundary was calculated

Also, several experiments were devised in order to reaffirm assumptions used in initial calculations. The first experiment, as shown in Figure 17 shows a basic setup involving concentric 10 foot long iron pipes placed at the electron emitter. The intention of the experiment is to confirm electron beam spread angle. Utilizing electronic dosimeters, dose rate was measured across the iron pipe to reveal the location along the length of the pipe which would show a spike in dose rate. Gauging the general location along the length of the pipe that would show a large spike in dose rate would reveal the boundaries of the electron beam, exposing the true spreading angle of the beam. In order to properly map the radiation field and confirm calculations, dosimeters were also placed at various parts of the room. It was decided that the number of dosimeters was insufficient and the data unreliable due to malfunctioning equipment.

[pic]

Figure 17- Experiment Schematic of Concentric Iron Pipes

*Note 1: Ironite Shielding has been replaced with concrete.

It was determined that a more accurate experiment measuring the radiation field should be conducted. Recently a team was sent to Ohio to set up a similar, but more thorough experiment. Instead of using electronic dosimeters, TLD’s (thermo luminescent dosimeters) were used, which are much more accurate. Also, there were two sets of 45 TLD’s placed in many more locations around the e-Zapper, in the iron tubes, and around the room. This experiment should yield a much better picture of the radiation field. From this data, it was possible to create a radiation map as seen in Figure 18. The radiation map shows that the area behind the e-Zapper received less than 50 mrem dose in the 20 second shot used in the experiment. Therefore, the location of the operator should be behind a right-angle line of the e-Zapper. The experiment also shows that it is possible to shield the operator. As seen in Figure 18, one half inch of lead effectively reduced the radiation field to zero. Unfortunately, the experiment did not give sufficient information to design an efficient shield. More experiments will be required in order to produce an effective shield design. It is also worth noting that any area colored red in the radiation map received more than the lethal dose of 500 Rads (or 500,000 mrem) in the 20 second shot. Without the iron pipes, the spread of the lethal zone would have been even larger. Figure 19 shows the 8 dosimeters placed in one end of the iron pipes.

[pic]

Figure 18- Experimentally Determined Radiation Map

[pic]

Figure 19- Iron Pipes with Dosimeters

Beam stop:

One of the accomplished tasks was to calculate the required dimensions for a wall of different materials to stop the electron beam and other radiation if the wall were placed in the line of fire. Similarly, once more accurate radiation in the direction of the operator is attained, it will be possible to use this equation to calculate necessary operator shielding. It was assumed that the wall would be placed ten feet from the e-Zapper, and the spread of the beam was 15 degrees. The equation that was used was equation (3).

[pic] (1)

where D is the desired dose rate at the edge of the wall (set to the safe value of 2 mrem/hr), Do is the initial dose rate hitting the wall, x is the required dimension, and TVL is the tenth value layer which is based on the material and the incident electron energy. From the radiological projection calculations, the electron energy at ten feet was found. Using this value, Do was calculated. TVL was found from the plots in Appendix E of NCRP 51. The values for TVL were 33 cm for concrete, 9.5 cm for iron, and 5.6 cm for lead. Once all these values were substituted into the equation, it was possible to solve for x. The calculations, however, do not match with the experimental results. The calculations yielded a required thickness of 7 feet of concrete, 2 feet of iron, and 1.2 feet of lead. The radiation map in Figure 18 shows that the current beam stop effectively stopped the radiation. The current beam stop is less than 1 foot thick, not 7 feet.

e-Zapper ranges:

The figure for dose ranges was generated using the radiological projection data and the inverse distance squared rule, which can be expressed as :

[pic] (4)

where D(p) is the dose rate at some point, D(1m) is the dose rate at one meter, and r is the distance to point p. D(1m) was found from the radiological data and by varying either the distance r, or the desired dose rate D(p), the other variable could be solved. Two of the ranges were calculated based on the lethal dose of 500 rads given in a specific period of time. One range was set to 100m for the sake of reference and the dose rate was calculated. The last range was calculated using the safe dose rate of 2 mrem/hr. The results of these calculations are shown in Figure 20.

[pic]

Scale: I I I

1 m 100 m 9000 m

Figure 20-Various Calculated Ranges of e-Zapper Radiation (Assuming no shielding, beam energy of 6 MeV, beam current of 5 mAmps, and constant high fire mode)

Feasibility of using the e-Zapper as an offensive weapon:

The e-Zapper could potentially be used as an offensive weapon, considering that it can produce a lethal radiation dose. Radiation at the lethal dose of 500 Rads does not kill immediately, but the radiation is relatively silent and the targets probably would not be aware that they had received the radiation. As shown in Figure 17, the e-Zapper produces a dose of over 5,000 Rads within the first few feet with a 20 second shot. As stated previously, the lethal zone of the e-Zapper would be wider if the iron pipes were removed. More experiments are required to determine the actual effective lethal distance. The beam is less effective at long ranges, but it would be a silent, delayed way to kill an enemy.

Program Management

Division of Labor

Team Leader: MIDN 1/C Emison, 071926, 28th Company, 443-321-8217

Vehicle Dynamics MIDN 1/C Merrick, 074464, 11th Company, 443-321-7016

MIDN 1/C Schnappinger, 075940, 11th Company, 443-321-7045

Power Generation MIDN 1/C McHugh, 074362, 19th Company, 443-321-4351

MIDN 2/C Schwamberger, 085922, 8th Company, 443-321-3254

Radiation/ MIDN 1/C Tang, 076612, 20th Company, 443-321-4401

Heat Transfer MIDN 1/C White, 077206, 19th Company, 443-321-4309

The following is the work breakdown schedule of each group for the next semester. The gant chart is attached in Appendix A.

Work Breakdown Schedule

Vehicle Dynamics

Process Prerequisites

Platform Selection:

A) Determining Weight Requirement

B) Determining Vibration/Isolation

C) Evaluating Options A

D) Selecting Platform C

Load/Unloading: D

E) Plans for Front Support

F) Caster/Wheel Type Selection E

G) Plans for Track System

Determining Methods for Loading: E

H) Determining Strength Requirements

I) Determining Weight Requirements

J) Determining Winch Requirements

K) Determining Mobility Requirements

L) Evaluating Options H, I, J, K

M) Method Selection L

Refining the Chosen Selection: M

N) Determining Layout in Trailer

O) Center of Gravity Calculations

P) Moment Loading

Power Generation

Process Prerequisites

Research:

A) Preliminary Research

B) 3 Phase Power Research

C) Generator Research

D) Waveguide Research

Calculations and Drawings:

E) 3 Phase Power Calculations

F) Draw in Current Electrical System

G) Draw Patch Assembly

H) Modify Electric Schematic F

Experimentats

I) Range Testing

J) Electrical Testing

K) Generator Testing

Vendor Search:

L) Finalizing Generator

M) Comparing Generators L

N) Trailer/Vehicle Selection

Heat Transfer and Radiation

Research and Practicum:

A) Radiation Research and Education

B) Heat Tranfer Research and Education

Calculations

C) Anterior Radiological Projection Estimation of e-Zapper

D) Beamstop Design

E) Cooling System Determinations (Liquid)

F) Cooling System Determinations (Air)

Experiment

G) Cooling System (Liquid) Specification Measurements

H) Operating Surface Temperature Measurements

I) Anterior Radiation Experiment

J) Analyzation of Anterior Radiation Field I

K) Posterior Radiation and Beam Current Density Experiments

L) Analyzation of Posterior Radiation Field K

M) Determine Beam Current and Duration of Fire K

Design

N) Cooling System E,F,G,H

Vendor Search

O) Search for Chiller Vendor (Liquid Loop)

P) Search for Shielding Vendors

Q) Search for Air Conditioning Vendors (Ambient Air)

R) Search for Cooling System Component Vendors N, S

Final Decisions

S) Determine Chiller O

T) Contact Chiller Vendors S

U) Contact Cooling System Component Vendors R

V) Contact Shielding Vendors

Budget

The Office of Naval Research handles funding for the e-Zapper project. So far this semester there have been 10 trips to Newark, Ohio costing approximately $300 a piece Also, the 4 load cells costing a total of $1500 were purchased to weigh the e-Zapper. All of the other expected expenses were delayed due to the non-functionality of the machine. The final quotes on a chiller and generator are forthcoming and will be given to ONR to help acquire the required equipment. A full budget will the be constructed for the acquisition of all components recommended.

Conclusion and Recommendations

The e-Zapper team this semester has developed a layout for mobilizing the e-Zapper that could be easily implemented with the funding from ONR and the manpower to install the equipment. The team has addressed the issues of selecting a platform, transporting the e-Zapper in and out of that platform, the layout within the platform, powering the e-Zapper, heat generated and a cooling system, and has begun creating a radiation map to be used to design shielding.

The continuation of this project should include several things. First, all team members should go to the site of the e-Zapper before beginning any other research on the project and be given an overview of the mechanics of the parts relevant to them. This brief should be done by the mechanics and technicians who work with the e-Zapper on a fundamental level instead of focusing on how to eliminate threats and firing the beam which are not the focus of this team. Hands on experience with the e-Zapper should become much easier when it is transported to Indian Head over the summer.

Additionally, efforts should be made to coordinate with all external parties over what exactly needs to be done and what are feasible tasks for midshipmen. The design of a plan for mobilizing the e-Zapper involved many tasks being done that were unnecessary or things being done at the last minute based on a lack of knowledge. There should be more clearly defined guidance between trial and error and things that are just unnecessary.

Appendices

Appendix A- Gant Chart

-----------------------

[1]

[2]

[3]

[4]

[5] “Stopping Powers for Electrons and Positrons”, M. Berger, ICRU-37 , Washington D.C., 1984

-----------------------

Sump Heater

e-Zapper Coolant Medium

Sump Coolant Medium

*drawing not to scale

e-Zapper

Centrifugal pump

Sump / heat exchanger

X_Control Systems

X_Generator/Chiller

X_Trailer Weight

X_Power Cabinet

X_Fulcrum

X_e-Zapper

44.5 ft

F_Control Systems

F_Trailer Weight

F_Shielding

F_Generator/Chiller

X_Shielding

F_Power Cabinet

F_e-zapper

Gooseneck Hitch Location

Fulcrum

Trailer Bed/Simple Beam

CG Calculation:

7750 lb * x (ft) = 2320 lb * y (ft)

X=2.3 ft

Y=7.7 ft

28”

E-Zapper

Center of Gravity

Point Load of 2320 lbs

Point Load of 7750 lbs

Front of e-Zapper

Rear of e-Zapper

45”

120”

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