1. Group Members: Mike Oertli Jonathan Karnuth Jason Rancier September 11, 2008

2. Project Overview Linear accelerator Voltage applied to rails Projectile shorts out rails creating EM field Pneumatic kick-start Projectile accelerates forward

3. Basic Design Conducting rails mounted to non-conducting surface Capacitor array PCB, logic, and UI Conducting metallic projectile

4. Objectives Safety!!! Adjustable voltage from capacitor bank User interface Keypad and LCD Sensor data Velocity calculations Remote/Hands off (Safety!)

5. Approach Split into 3 main areas 1. Railgun 2. Control system 3. User interface Each person focus on one area Communication and compatibility is key

6. Power Supply Brute Force discharge Basic supply, dumps a lot of current directly on rails Simple to design, overkill on capacitance Inefficient, back EMF problems Recharger Supply Complex LC timing based on rails Prone to failure with bad design Requires more capacitors (if polarized are used) Much more efficient Fast recharging

7. Capacitors Capacitance: 610,000µF Voltage: 20VDC 30VDC surge ESR: 2.1mΩ max Type: Electrolytic Number used: ~20 Cost: ~ $400

8. Capacitor Array Mounted capacitors Connected by switches controlled by logic based on input voltage from user Logic will be based on test shots In enclosed case (Safety) Other possibilities: Manual switches Switch mode power supply Input inductor between array and rails Ramps current to rails Avoid discharging capacitors too fast

9. Rail types Cylindrical Easier to fabricate Fewer pieces Stronger using less material Rectangular Easier to mount Better electrical properties, distributed current

10. Example of rail Conducting rails

11. Materials Rails: Brass Projectile: Aluminum Base: Garolite & Teflon Capacitors: 20x 0.6F 20 v Electrolytic Microcontroller: MSP430 family - 16 bit PCB Power supply Sensors (EM, voltage) Keypad and LCD

12. Brass Rails Composite: ~70% Copper, ~.07% Lead, ~.05% Iron, Remainder Zinc Electrical Conductivity: 28% IACS Electrical Resistance: 6.2µΩ/cm Friction: Very low with Most metals Melting Point: 910 o C Inner/Outer Diameter: 0.87”/1” Cost: $58.68 for 36”

13. Projectile Metal: Aluminum Composite: 2011 Temper: T3 Part #: 88615K411 Melting point: 540 o C Electrical Conductivity: 45% IACS Electrical Resistivity: 3.8µΩ/cm Diameter: 7/8” Length: ~1” Cost: $17.41/foot

14. Pneumatic Kick-start Avoids spot welding projectile Added kinetic energy Eliminates static friction coefficients Compressed Air/CO2 system Activated by Microcontroller post safety checks

15. Chassis Specs Inner SupportOuter Sheath CompositeTeflon PTFEGrade G-10/FR4 Crosswise Tensile Strength 3,900 PSI35,000 PSI Melting Point 335 o C ~384 o C Max Temp Dielectric Strength19.7MV/m15.7MV/m Inner/Outer Diameter.875”/1”1”/1.375” Cost$9.21 per 12”$92.16 for 39” Part #8547K298668K49

16. Safety Features Voltage sensors on rails, cap bank, & source Kill power if out of expected range EM Field Sensor Faraday cage if EM field great enough Plexiglas casing Keep user isolated from high voltages and short circuited rails

17. Block Diagram MSP430xxxx Power Supply Keypad LCD Rails Capacitor Array Kill Switch LEDs Inductor

18. Microcontroller MSP430xxxx family Testing on MSP430F169 16-bit for accurate calculation of sensor data Control safety logic based on sensor values Disconnect switches from caps to rails Display values on LCD

19. Software Engineering Interface with Matlab Import sensor data Statistical analysis Display results to user as graphs and tables Maintain records

20. PCB Elements Power supply MSP430 Family Debug/information LEDs LCD (3 or 4 rows) Keypad input Communication with sensors(A/D)

21. Sensor Measure voltage at high sample rate Used for analysis and safety logic Implementation: Voltage transducer Sample @ 10 MHz + Response time < 50μs

22. User Interface Basic keypad Input desired voltage to apply to rails 3 or 4 line LCD on PCB Output sensor data and statistics Basic input user interface If time: Keyboard input Computer monitor with GUI Matlab sensor data analysis

23. Expenses Item# NeededCost perTotal Cost Rails2x36”$58.68$117.36 Garolite2x42”$46.53$120 Capacitors20$20$400 Projectiles1’$17.41 PCB2$30$60.00 Controller3(donated)$0 Misc/Sensors$300 Estimated Total~$1014.77

24. Division of Labor JonathanMikeJason Primary Responsibility Rail fabrication & Safety Microcontroller & Safety Power systems & Safety

25. Schedule

26. “Real World” Application Control System for other high voltage applications Accelerator for fun, military, other scientific research Capacitor array for high current burst power systems Sensor to Matlab interface

27. Realization Stay under budget by getting donations Establish primary goals/reasonable functionality Operate within these Add incremental levels of difficulty based on time

28. Plan B Risk: Projectile fuses to rails Discontinuities in the rails and base Arcing- heat/damage to rails Unfamiliarity Sensing systems Matlab interface Recovery Ask for help! Use heavier duty components RTFM Have extra rails and projectiles ready

29. Questions?