1. TEAM TESLA Anthony Thompson Philip de la Vergne Aaron Wascom Brandon Sciortino 1

2. Overview Address concerns from previous PDR presentation Polarity Humidity Temperature Linear Actuator Breakdown Voltage at Sea Level Data Accuracy Data Frequency Requirements System Design Traceability Software Principal of Operation Payload Development WBS 2

3. Polarity 3 A comparison of breakdown voltages for positive and negative corona

4. Humidity 4 Effect of absolute humidity on the breakdown voltage of a 30cm point-to-plane spark gap Parameter: Voltage Positive D.C Voltage A.C. Voltage

5. Temperature 5 Lower temperatures mean slower molecules, which means that the particles in the air collide with less kinetic energy. This drop in energy apprehends the production of ions and free electrons, which decrease the current created through the corona breakdown mechanism

6. Data If the payload passes through a cloud the humidity will change rapidly making Its effect on the breakdown voltage more evident. The Smallest cloud () is about 1000 ft. tall so it insure we get a measurement inside the cloud we will measure no less than every 500 feet We ascend 1000 ft. per min and want to sample every 500 ft. so we will measure every 30 second's. How accurate to our results need to be? Temperature, Pressure, Humidity, Current, Voltage 6

7. Linear Actuator Data must be taken every 500 feet. A actuator will increase the distance across the spark gap to prevent a breakdown and the distance at that instant will be recorded. An analysis of the expected results of this method reveals that it is not plausible. The linear actuator would have to change the spark gap 19 mm every 500 ft. Assuming a constant voltage of 3000 V, the sea level pressure distance product on the x-axis of Paschen’s curve is 3 Torr-in. This requires a gap distance of 1.002 mm the gap distance would have to change by 19 micrometers every 7

8. Technical Requirements The payload shall have a temperature sensor that can measure from 40 °C to -70° C and operate throughout the flight. The payload shall measure Temperature to an accuracy of 1 degree Celsius The payload shall measure Pressure to an accuracy of 1 Pa The payload shall have a humidity sensor that can measure 0 to 100% relative humidity and operate throughout the flight. The payload shall measure relative humidity to an accuracy of 1% The payload shall have a pressure sensor that can measure 101.3 kPa to 1 kPa and operate throughout the flight. 8

9. Technical Requirements 9 The payload shall provide up to 4.5 kV in order to create a corona discharge at ground level The electrodes shall have a point to plane configuration The payload shall have a 1 mm spark gap The electrodes shall be properly conditioned to provide a smooth finish The anode shall be composed of a gold-plated copper point and the cathode shall be composed of copper The payload shall weigh less than 500 grams. The payload shall have two holes 17 cm apart for interfacing with the LaACES balloon. Record and store data from flight so that it can be retrieved after flight for analysis The payload will have enough power to operate throughout entire flight.

10. Science Requirements 10 The electrodes shall be exposed to external temperature and humidity conditions This payload shall consider a corona discharge of 10 -5 Amps to be a breakdown The payload shall increase the voltage with an accuracy of The electrode configuration shall create a positive corona discharge The onboard electronics shall be protected by a Faraday Cage around the spark gap The payload shall record data every 500 feet to observe any clouds in the flight profile The payload shall record temperature, pressure, humidity, and breakdown voltage from 0 to 100,000 feet

11. System Design 11

12. Principle of Operation Measure pressure, temperature, humidity, breakdown voltage, and current across the spark gap Sensors: Piezoelectric, thermistor, relative humidity Exposed to environmental conditions Voltage across spark gap increased until 10 microamps are measured Voltage comparator observes corona discharge Switch opened, data recorded, voltage set to zero 12

13. Electrical Development Temperature Sensor Select sensor that operates within requirements Measure from -70 to 40 degrees Celsius Operates within 40 degrees Celsius Accurate to +/- 1 degree Celsius Order Sensor Draw preliminary schematic Measure accuracy and compare to data sheet accuracy Calibrate sensor according to difference between data sheet and observed accuracy Determine necessary gain for op-amp conditioning circuit Select resistors for op-amp circuit Test to operate under 100% relative humidity Test performance in thermal/pressure environments 13

14. Electrical Development 14 Pressure sensor Select sensor that operates within requirements Measure from -70 to 40 degrees Celsius Operates within 40 degrees Celsius Accurate to +/- 133 Pa Order Sensor Draw preliminary schematic Measure accuracy and compare to data sheet accuracy Calibrate sensor according to difference between data sheet and observed accuracy Determine necessary gain for op-amp conditioning circuit Select resistors for op-amp circuit Test to operate under 100% relative humidity Test performance in thermal/pressure environments

15. Electrical Development 15 Humidity sensor Select sensor that operates within requirements Measure from -70 to 40 degrees Celsius Operates within 40 degrees Celsius Accurate to +/- 1% Order Sensor Draw preliminary schematic Measure accuracy and compare to data sheet accuracy Calibrate sensor according to difference between data sheet and observed accuracy Determine necessary gain for op-amp conditioning circuit Select resistors for op-amp circuit Test to operate under 100% relative humidity Test performance in thermal/pressure environments

16. Current Detection 16 Flight simulation Compare to expected results to confirm system design Draw Preliminary Schematic Select resistor for voltage comparator circuit Must allow for 10 microamps created at lowest voltage created Select threshold voltage across resistor for voltage comparator Select voltage comparator from threshold voltage, environmental requirements and 2ms response time Operate from 40 to -70 degrees Celsius Select JK Flipflop Operate from -70 to 40 degrees C 2ms response time Determine high voltage at JK Flipflop for high at BASIC Stamp Select transistor Response time less than 2ms Test transistor to confirm response time Purchase materials for electrode configuration Test to determine breakdown voltage at sea level Finalize circuit schematics Flight simulation To confirm system design

17. Mechanical Development 17 Determine required volume to contain components Determine method of component attachment to payload Determine required dimensions for interfacing and components Thermal test to determine required thickness Shock test Add to weight budget

18. Software Development 18 Read/Write to EEPROM Determine syntax needed to input and output data to EEPROM Develop subroutine to write data to EEPROM Develop subroutine to prevent overwriting Test to confirm coding Reading sensors Develop subroutines to Record data from ADC Read data from EEPROM Timestamp data Control Voltage Develop subroutine to increase voltage Test output voltage sent to DAC from BASIC Stamp Ensure HVDC output voltage is the same value indicated by BASIC Stamp Develop subroutine to record breakdown voltage Develop subroutine to remove voltage across spark gap

19. Mission Development 19 Full flight simulation prior to trip Bring extra batteries, sensors, voltage comparator, JK flipflop, resistors, and HVDC Assemble payload 24 hours prior to launch Test operation off all components prior to launch Launch Run Pre-flight software that leads into operations software

20. HVDC Development 20 Select and order HVDC based on electrode testing Required breakdown voltage from materials testing Draw Preliminary Schematic Test and compare measured accuracy to data sheet Calibrate HVDC according to difference between data sheet and tests Determine required input voltages to create desired output voltages Test performance in thermal/pressure environment Draw finalized schematics Flight simulation Compare to expected results to confirm system design Add all sensors to weight and power budget

21. WBS 21

22. WBS 22

23. WBS 23

24. Overview Mission Goal Science Objectives Technical Objectives Science Background Science Requirements Technical Requirements System Design Power Budget Software Design Structural Design Management 24

25. Mission Goal To study the effects of humidity and temperature on the corona breakdown of the atmosphere in an effort to prevent sparking and ensure safety on future payloads. 25

26. Science Objectives Observe the effect of temperature on corona breakdown voltage of the atmosphere Observe the effect of humidity on corona breakdown voltage of the atmosphere 26

27. Technical Objectives Measure temperature of the atmosphere Measure pressure of the atmosphere Measure humidity of the atmosphere Measure the corona breakdown voltage as a function of pressure and gap distance Measure the current across the gap Meet all payload standards set by LaACES 27

28. Paschen’s Curve 28 http://www.sciencedirect.co m/science/article/pii/S1466 85640200067X

29. Electron Avalanche 29

30. Electrode Geometry & Polarity 30 http://etd.auburn.edu/e td/bitstream/handle/10 415/2044/Lipham_Mar k_Thesis.pdf?sequenc e=1

31. Effects of Humidity Humidity has an effect on the corona breakdown voltage by rearranging the polar water molecules entering the electric field. 31

32. Effects of Temperature Temperature has an effect on the corona breakdown voltage through increasing the kinetic energy of the molecules within the spark gap. 32

33. Electrode Material 33 http://ieeexplore.ieee.or g/xpls/abs_all.jsp?arnu mber=13866&tag=1

34. Electrode Roughness http://www.elect.mr t.ac.lk/HV_Chap1.p df 34

35. Environmental Conditions Team Philosohook’s Results 35

36. Science Requirements The electrodes shall be exposed to external temperature and humidity conditions. This payload shall successfully create a corona discharge. The electrode configuration shall create a positive corona discharge. The payload’s onboard electrons shall be protected with a Faraday cage. 36

37. Technical Requirements The payload shall have a temperature, pressure, and humidity sensor that can measure and operate throughout the flight. The payload shall detect a corona discharge by intercepting a radio interference and detecting a current spike. The payload shall have an HVDC Converter. The electrodes shall have a point-to-plane configuration. The electrodes shall be properly conditioned. The anode shall be composed of a gold-plated copper point and the cathode shall be composed of copper. 37

38. High Level System Diagram 38

39. HVDC Converter SMHV Series sub-miniature regulated HV DC 0.434 cubic inch converter 0 to 10kV at 1 W of power 5VDC input On/Off Pin Voltage and Current monitor outputs Current Limiting Control inputs SHORT LEAD TIME 39

40. Current & Radio Wave Sensor Interface 40

41. Power Budget ComponentCurrentVoltagePowerFlight TimeCapacity HVDC Converter SMHV Series EMCO Full Load – 300 mA5 V1500 mW4 minutes20 mA-hours Stand by – 20 mA5 V100 mW3 hours 56 minutes 79 mA-hours Humidity Sensor HIH-5030 Series 200 μA2.7 V2.5 mW4 hours2 mA-hours BalloonSat52 mA12 V1790 mW4 hours208 mA-hours Pressure Sensor 1230 Series Measurement Spec 2 mA12 V24 mW4 hours8 mA-hours Temperature Sensor 44000 series OMEGA 1 mA12 V12 mW4 hours4 mA-hours DAC160 μA5V.8 mW4 hours.64mA-hours Totals: Full Load – 355.2 mA Stand by – 75.2 mA 12 VStand by – 1930 mW Full Load – 3330 mW 4 hours322 mA-hours 41

42. Power Source AAA Energizer L92: Lithium vs. Alkaline 42 http://data.energizer.com/PD Fs/l92.pdf

43. Flight Software Flowchart 43 Temperature: 1 byte Humidity : 1 byte Pressure : 1 byte Time : 3 bytes Voltage : 2 byte Voltage Redundancy: 2 byte Current : 1 byte Current Redundancy :1 byte Radio : 1 bit Total : 97 bits

44. Thermal Design DeviceUpper Temp (°C)Lower Temp (°C) ADC, RTC, BASIC Stamp, EEPROM, DAC 80-40 Pressure Sensor 125-40 Humidity Sensor 125-50 Temperature Sensor 120-80 HVDC 85-55 Current Sensor 85-40 Energizer Lithium Batteries 60-40 44

45. External Structure 1.2cm 17cm 15cm 45

46. Internal Structure 46

47. Weight Budget ItemMassUncertaintyMeasured or Estimated BalloonSat 67.6 g± 5gMeasured Signal Conditioning 70 g±5Estimated and Sensors Packaging 100 g± 10gEstimated Wiring 15g±5gEstimated Power Supply 150g±10gEstimated Totals: 402.6g±35g 47

48. Group Structure Functional GroupTeam Member Project ManagementAnthony Thompson Science RequirementsChris Rowan ElectronicsAaron Wascom Flight SoftwareAaron Wascom Mechanical IntegrationPhilip de la Vergne System TestingBrandon Sciortino Data Processing and AnalysisAnthony Thompson DocumentationChris Rowan 48

49. WBS 49

50. Milestones 50

51. Risk Management Risk Event LikelihoodImpactDetection DifficultyWhen Faulty Power Supply 452 Flight Faulty Preflight Procedure 244 Pre-Flight Incorrect Coding 351 Calibration Sparking 332 Flight Losing a Team Member 231 Pre-Flight Faulty Parachute 131 Flight Component Failure 442 During Flight/ Testing Impurities on Electrode Surface 342 Pre-Flight/During Flight Loss of Payload 355 Post-Flight External Deadlines not Met 253 Pre-Flight Over Budget 342 Pre-Flight Memory Deficiency 443 Flight Unexpected Environmental Conditions 231 Flight Part Unavailability 332 Pre-Flight Change in Electrode Distance 255 Flight Bad Connection During Fabrication 244 Fabrication 51

52. Risk EventResponseContingency PlanTriggerResponsibility Faulty Power Supply ReduceSwitch out with new Batteries Sensors Malfunction or Break Philip de la Vergne Faulty Preflight Procedure ReducePre-Flight To-Do listPre-Flight Set upAnthony Thompson Incorrect Coding ReduceRecodeWill not load to BASIC Stamp Aaron Wascom Sparking ReduceElectrode geometry, sparking type, and Faraday cage Faulty ProgrammingAaron Wascom Losing a Team Member ReduceWork is shared among remaining members Sudden Workload Increase All Members Faulty Parachute TransferBuild payload to protect data storage Parachute failureDr. Guzik Component Failure TransferOrder another from a different company or have a spare Device does not operate properly Aaron Wascom Impurities on Electrode Surface ReduceCheck surfaces prior to launch Condensation or dustBrandon Sciortino Loss of Payload SharePrepare Failure ReportLack of PayloadAll Members External Deadlines not Met TransferPray we don’t get firedLack of Project Management All Members Over Budget TransferFind cheaper Component or Apply for More Funds Cost AnalysisAll Members Memory Deficiency RetainObtain more memoryLoss of Data PointsAnthony Thompson Unexpected Environmental Conditions ReduceIncrease Sensor RangesSensor Failure and Data Spikes All Members Part Unavailability ReduceDifferent SupplierResearchSupplier Change in Electrode Distance ReduceStrengthen stability of electrodes Carelessness during Fabrication Chris Rowan Bad Connection During Fabrication TransferDouble and triple check all solder joints Faulty circuitChris Rowan 52