1 / 24

Microwave Calorimeter

Microwave Calorimeter. Sponsor: Chris Leach Merlyn Bluhm Chris De La Cruz Ben Schaefer. High Power M icrowaves (HPM). ~2-5GHz, ~1GW Compare to 783GW Used in High resolution radar Military “soft kill” of electronics IED’s. Calorimeter Overview. Used to measure microwave power

paytah
Download Presentation

Microwave Calorimeter

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Microwave Calorimeter Sponsor: Chris Leach Merlyn Bluhm Chris De La Cruz Ben Schaefer

  2. High Power Microwaves (HPM) • ~2-5GHz, ~1GW • Compare to 783GW • Used in • High resolution radar • Military “soft kill” of electronics • IED’s

  3. Calorimeter Overview • Used to measure microwave power • Traditionally used to measure endo- and exo-thermic chemical reactions • Container of alcohol • Absorbs microwave power • Expands into capillary tube • Gives energy change

  4. Subcomponents • Physical housing • Microwave-transparent case • Capillary tube • Microcontroller • Sensors • Heating/calibration coils • Feedback • Signal/LCD output

  5. Physical Housing - Case

  6. Physical Housing–Capillary Tube • Coaxial capillary • Height measured via resistance • Wheatstone bridge

  7. Microwave Source • ~1GW • ~14J

  8. Goals of System • Accurately measure power • Provide method of calibration • Output scaled signals to oscilloscope and computer

  9. Roles of Team Members and Sponsor • Chris Leach (Sponsor) • Calorimeter Body Design and Assembly • Physics Guru • Merlyn • Software Development / Signal Processing • Chris • Cap Tube Instrumentation, Temp Measurement • Ben • Amplifiers, DAC, Sample and Hold, Heater Coil

  10. Microcontroller Block Diagram

  11. Arduinovs PIC • $30 • C++ Programming • 14 Digital I/O ports (6 PWM) • 6 Analog input ports • Stackable thermocouple module • Free multiplatform software, tons of sample code • No direct access to digital I/O ports • Multiplexed analog ports • Complications with installed software

  12. Project Deliverables • Calorimeter Body • Control Unit • Capillary Tube • Heater / Calibration Coils • ? Temp Sensor / Feedback • Power System • MCU • Software • Signal Scaling / Displaying • Calibration Controller • Data Archiving • Calibration Phase • Experimental Data

  13. Calorimeter Specifications • Physical Dimensions • 4cm deep X 40cm diameter. Driven by: • source aperture diameter • attenuation profile of source • Material • Aperture: HDPE/PiezoGlass • Body: HDPE/PiezoGlass or different material • Absorbing Material: Ethyl alcohol. (5,027 cm3) • Machining capabilities will play a major role

  14. Calorimeter Specifications Cont… • Removable Sensor Interface • Different tube sizes or additional thermocouples • Our Idea • Source and calorimeter specs will yield: • ΔT = 6.25 x 10-3°C • ΔV = 0.0325 cm3

  15. Capillary Tube • Physical Dimensions • Tube: 0.0314” (0.08 cm) dia X 4.0” (10.2 cm) length • Wire: 0.010” (4e-3 cm) dia • Predicted fill level during experiment: 3.5” (8.9 cm) • Must hold off main alcohol volume • Resistance • Conductivity of alcohol: 5.63e-8 S/m? => 17.8 MΩ/m • For coaxial geometry: R’ = 3.11 MΩ/m • Experiment • For 1cm initial fill level: R0 = 31 kΩ • For 8.9 cm displacement at 14 J: delta R = 278 kΩ • Wheatstone bridge should not be required • Must know voltage breakdown specs of alcohol to optimize detection circuit

  16. Temperature Measurement • Expected Temperature Change: 6.25 x 10-3 °C • Very, very low and atypical • Thermocouple • Sensitivity: 40 μV/°C , Accuracy: 1°C • Expected output: 0.24 μVw/o amplification • Not feasible • RTD – Resistance Temperature Detector • Sensitivity: 1.8 mΩ/°C , Accuracy: 30 x 10-3°C • Current constraint: 1mA • Expected output w/ Wheatstone bridge: 1 μVw/o amplification • Viable option but is accuracy adequate? • May forgo temperature measurement • Physics say the capillary tube should be adequate

  17. Heater Circuit • 300W DC Power Supply • PID algorithm to control temp • NiChrome Wire • Ohms/ft • Use IGBT for switching • Fast response time • Large power rating (1KW)

  18. Amps, DAC, S&H • Amplify small voltages from capillary tube and temp sensor • -mV => 0-5V Scaled • DAC: Generate analog data from MC • - TBD • S&H: Closed loop system between MC and S&H • - Collect data when we want it

  19. Software Development • Implement sample code for analog voltage mapping • Read-in capillary tube resistance via voltage change • Extrapolate total energy deposition from calorimeter dynamic equations • Implement PWM signal to calibration power system • Display / record experimental data

  20. Challenges and Concerns • Current Issues • ΔT, 6.25 x 10-3 °C • Resolved Issues • MCU choice • Alcohol Volume

  21. Milestones for End of Fall Semester • Cap Tube Bench Test • Prototype Software for Functional I/O • Heater System Spec’ed • Power • NiCr • Other components • Calorimeter Fab Complete

  22. Major Schedule Milestones • Calorimeter Fab – Dec 2011 • Controller Development – Dec 2011 • Calibration – Feb 2012 • Experiment/Testing – Apr 2012

  23. Why This is a Good Senior Design Project • Entrenched in all phases from initial design to final testing. • Combination of digital, analog, software, power. • Project emulates real world job scenario. • Team effort

  24. Questions?

More Related