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TEAM TESLA Anthony Thompson

Philip de la Vergne

Aaron Wascom

Brandon Sciortino

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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

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Polarity

A comparison of breakdown voltages for positive and negative corona

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Humidity

Effect of absolute humidity on the breakdown voltage of a 30cm point-to-plane spark gap

Parameter: VoltagePositive D.C Voltage

A.C. Voltage

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Temperature

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

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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

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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

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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.

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Technical Requirements• 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

• 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

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System Design

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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

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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

14 Electrical Development

• 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

• 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

• 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

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Mechanical Development• 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

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Software Development• 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

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Mission Development

• 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

• 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

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WBS

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WBS

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WBS

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Overview

• Mission Goal• Science Objectives• Technical Objectives• Science Background• Science Requirements• Technical Requirements• System Design• Power Budget• Software Design• Structural Design• Management

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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.

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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

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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

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Paschen’s Curve

http://www.sciencedirect.com/science/article/pii/S146685640200067X

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Electron Avalanche

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Electrode Geometry & Polarity

http://etd.auburn.edu/etd/bitstream/handle/10415/2044/Lipham_Mark_Thesis.pdf?sequence=1

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Effects of Humidity

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

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Effects of Temperature

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

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Electrode Material

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=13866&tag=1

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Electrode Roughness

http://www.elect.mrt.ac.lk/HV_Chap1.pdf

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Environmental Conditions

Team Philosohook’s Results

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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.

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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.

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High Level System Diagram

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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

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Current & Radio Wave Sensor Interface

Resistor

Conditioning ADCV out

CurrentMonitor

PinConditioning ADCV out

RWSensor

Conditioning ADCV out PeakDetector

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Power BudgetComponent Current Voltage Power Flight Time Capacity

HVDC ConverterSMHV SeriesEMCO

Full Load – 300 mA 5 V 1500 mW 4 minutes 20 mA-hours

Stand by – 20 mA 5 V 100 mW 3 hours 56 minutes

79 mA-hours

Humidity SensorHIH-5030 Series

200 μA 2.7 V 2.5 mW 4 hours 2 mA-hours

BalloonSat 52 mA 12 V 1790 mW 4 hours 208 mA-hours

Pressure Sensor1230 Series Measurement Spec

2 mA 12 V 24 mW 4 hours 8 mA-hours

Temperature Sensor44000 seriesOMEGA

1 mA 12 V 12 mW 4 hours 4 mA-hours

DAC 160 μA 5V .8 mW 4 hours .64mA-hours

Totals:

Full Load – 355.2 mAStand by – 75.2 mA

12 V Stand by – 1930 mWFull Load – 3330 mW

4 hours 322 mA-hours

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Power SourceAAA Energizer L92: Lithium vs. Alkaline

http://data.energizer.com/PDFs/l92.pdf

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Flight Software Flowchart

Temperature: 1 byteHumidity : 1 bytePressure : 1 byteTime : 3 bytesVoltage : 2 byte Voltage Redundancy: 2 byteCurrent : 1 byte Current Redundancy :1 byteRadio : 1 bit

Total : 97 bits

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Thermal Design

Device Upper Temp (°C) Lower Temp (°C)

ADC, RTC, BASIC Stamp, EEPROM, DAC

80 -40

Pressure Sensor125 -40

Humidity Sensor125 -50

Temperature Sensor120 -80

HVDC85 -55

Current Sensor85 -40

Energizer Lithium Batteries

60 -40

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External Structure

1.2cm

17cm

15cm

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Internal Structure

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Weight Budget

Item Mass Uncertainty Measured or Estimated

BalloonSat67.6 g ± 5g Measured

Signal Conditioning 70 g ±5 Estimated

and Sensors

Packaging100 g ± 10g Estimated

Wiring15g ±5g Estimated

Power Supply150g ±10g Estimated

Totals:402.6g ±35g  

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Group Structure

Functional Group Team Member

Project Management Anthony Thompson

Science Requirements Chris Rowan

Electronics Aaron Wascom

Flight Software Aaron Wascom

Mechanical Integration Philip de la Vergne

System Testing Brandon Sciortino

Data Processing and Analysis Anthony Thompson

Documentation Chris Rowan

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WBS

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Milestones

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Risk ManagementRisk Event Likelihood Impact Detection Difficulty When

Faulty Power Supply 4 5 2 Flight

Faulty Preflight Procedure

2 4 4 Pre-Flight

Incorrect Coding 3 5 1 Calibration

Sparking 3 3 2 Flight

Losing a Team Member

2 3 1 Pre-Flight

Faulty Parachute 1 3 1 Flight

Component Failure 4 4 2 During Flight/ Testing

Impurities on Electrode Surface

3 4 2 Pre-Flight/During Flight

Loss of Payload 3 5 5 Post-Flight

External Deadlines not Met

2 5 3 Pre-Flight

Over Budget 3 4 2 Pre-Flight

Memory Deficiency 4 4 3 Flight

Unexpected Environmental Conditions

2 3 1 Flight

Part Unavailability 3 3 2 Pre-Flight

Change in Electrode Distance

2 5 5 Flight

Bad Connection During Fabrication

2 4 4 Fabrication

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Risk Event Response Contingency Plan Trigger Responsibility

Faulty Power Supply Reduce Switch out with new Batteries

Sensors Malfunction or Break

Philip de la Vergne

Faulty Preflight Procedure

Reduce Pre-Flight To-Do list Pre-Flight Set up Anthony Thompson

Incorrect Coding Reduce Recode Will not load to BASIC Stamp

Aaron Wascom

Sparking Reduce Electrode geometry, sparking type, and Faraday cage

Faulty Programming Aaron Wascom

Losing a Team Member

Reduce Work is shared among remaining members

Sudden Workload Increase

All Members

Faulty Parachute Transfer Build payload to protect data storage

Parachute failure Dr. Guzik

Component Failure Transfer Order another from a different company or have a spare

Device does not operate properly

Aaron Wascom

Impurities on Electrode Surface

Reduce Check surfaces prior to launch

Condensation or dust Brandon Sciortino

Loss of Payload Share Prepare Failure Report Lack of Payload All Members

External Deadlines not Met

Transfer Pray we don’t get fired Lack of Project Management

All Members

Over Budget Transfer Find cheaper Component or Apply for More Funds

Cost Analysis All Members

Memory Deficiency Retain Obtain more memory Loss of Data Points Anthony Thompson

Unexpected Environmental Conditions

Reduce Increase Sensor Ranges Sensor Failure and Data Spikes

All Members

Part Unavailability Reduce Different Supplier Research Supplier

Change in Electrode Distance

Reduce Strengthen stability of electrodes

Carelessness during Fabrication

Chris Rowan  

Bad Connection During Fabrication

Transfer Double and triple check all solder joints

Faulty circuit Chris Rowan