Sponsor: Chris Leach Merlyn Bluhm Chris De La Cruz Ben Schaefer

 ~2-5GHz, ~1GW ◦ Compare to 783GW  Used in ◦ High resolution radar ◦ Military “soft kill” of electronics ◦ IED’s

 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

 Physical housing ◦ Microwave- transparent case ◦ Capillary tube  Microcontroller ◦ Sensors ◦ Heating/calibration coils ◦ Feedback ◦ Signal/LCD output

 Coaxial capillary  Height measured via resistance ◦ Wheatstone bridge

 ~1GW  ~14J

 Accurately measure power  Provide method of calibration  Output scaled signals to oscilloscope and computer

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

$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

– 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

 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 cm 3 ) ◦ Machining capabilities will play a major role

 Removable Sensor Interface ◦ Different tube sizes or additional thermocouples ◦ Our Idea  Source and calorimeter specs will yield: ◦ ΔT = 6.25 x °C ◦ ΔV = cm 3

 Physical Dimensions ◦ Tube: ” (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: R 0 = 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

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

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

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

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

Current Issues – ΔT, 6.25 x °C Resolved Issues – MCU choice – Alcohol Volume

 Cap Tube Bench Test  Prototype Software for Functional I/O  Heater System Spec’ed ◦ Power ◦ NiCr ◦ Other components  Calorimeter Fab Complete

 Calorimeter Fab – Dec 2011  Controller Development – Dec 2011  Calibration – Feb 2012  Experiment/Testing – Apr 2012

◦ Entrenched in all phases from initial design to final testing. ◦ Combination of digital, analog, software, power. ◦ Project emulates real world job scenario. ◦ Team effort