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Corona Threshold Voltage

Corona Threshold Voltage. Team Tesla: Chris Rowan Anthony Thompson Brandon Sciortino Philip de la Vergne Aaron Wascom. Presentation Purpose.

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Corona Threshold Voltage

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  1. Corona Threshold Voltage Team Tesla: Chris Rowan Anthony Thompson Brandon Sciortino Philip de la Vergne Aaron Wascom

  2. Presentation Purpose • This Presentation describes the preliminary design for the electrical breakdown experiment by Team Tesla for the LaACES Program. It fulfills part of the LaACES Project requirements for the Preliminary Design Review (PDR) to be held February 5,2013

  3. Document Scope • This Pre-PDR Presentation specifies the goal, objectives, background, and requirements for the electrical breakdown experiment and provides a guideline for the development of this payload under the LaACES Project. As such, these topics provide the basic for developing the PDR document and presentation.

  4. Mission Goal • To study the effects of humidity and temperature on the electrical breakdown of the atmosphere to prevent sparking and ensure safety. http://www.scienceclarified.com/Di-El/Electric-Arc.html

  5. Science Objectives • To conduct an experiment of the breakdown voltage in air at varying altitudes • To observe the effects that temperature and humidity have on our expected recreation of Paschen’s curve

  6. Technical Objectives • Measure temperature, pressure, humidity, current, and discharge voltage for the duration of the flight

  7. Science Background: Electric Discharge • Results from the creation of a conducting path between two points of different electrical potential • Three Types: 1. Corona Discharge 2. Spark Discharge 3. Brush Discharge

  8. Science Background:Corona Discharge • Occurs when the threshold voltage is breached • Only requires a high field strength • Current ranges around micro amps www.ce-mag.com/archive/1999/novdec/mrstatic.html

  9. Science Background:Spark Discharge • Occurs when the threshold voltage is breached • Complete ionization between electrodes • Maintained through a continuous high voltage source http://www.ehow.com/how_5884896_avoid-static-shock-open-door.html

  10. Science Background:Brush Discharge • In between the corona and spark discharge • It may appear as irregular luminescent paths http://www.electrotherapymuseum.com/2009/Protocakes/index3.htm

  11. Science Background:Corona Threshold Voltage • The potential at which corona is found to originate • Ohm’s law regime • Once the threshold is breached, current increase proportionality with voltage

  12. Science Background:Avalanche Effect Ionization of neutral atoms becomes possible when the KE of free electrons increase

  13. Science Background:Paschen’s Curve • V=f(pd) • The minimum of this curve corresponds to the minimum Pxd product for which the ionization effect is maximal http://www.sciencedirect.com/science/article/pii/S146685640200067X

  14. Science Background:Humidity • Partial breakdown threshold reverses from decreasing the threshold to increasing it once the pressure drops below a certain point • 20,000-25,000 ft. • Humidity can affect the magnitude of the current moving through the ionized air by up to 20% in a pulse corona • Pulseless corona and negative corona is not affected by changes in humidity

  15. Science Background:Atmospheric Conditions • Flight profile of expected payload environmental conditions http://www.aerospaceweb.org/question/atmosphere/q0090.shtml

  16. Science Background:Temperature • Temperature decrease ionization energy increase avalanche effect decrease breakdown voltage increase http://www.green-planet-solar-energy.com/double-glazing-materials.html

  17. Technical Background: Electrodes • Electrode - an electrical conductor that is used to make contact with a nonmetallic part of a circuit http://www.mikeblaber.org/oldwine/BCH4053l/Lecture05/Lecture05.htm

  18. Technical Background: Positive vs. Negative Corona Positive Negative More self-sustaining discharge Humidity has little to no effect Can only be sustained in fluids that contain electronegative molecules • More stable discharge • Linearly sensitive to changes in humidity • Produces less ozone than negative corona

  19. Technical Background:Electrode Geometry • Point • Small surface area • Concentrated electric field http://cnx.org/content/m42317/latest/

  20. Technical Background:Electrode Geometry • Plane • Evenly distributed electric field • Larger surface area

  21. Technical Background:Electrode Configuration • Point-Plane • Surface area ratio • Ionization energy http://www.imp.gda.pl/fileadmin/old_imp/ehd/coronast.gif

  22. Technical Background:Electrode Composition • Surface • Texture • Impurities • Surface Area • Electrode Material • Dielectric Strength • Conductivity

  23. Technical Background:Previous Experiments A mathematical model of the modified Paschen’s curve for breakdown in microscale gaps Influence of Axial Magnetic Field on the Electrical Breakdown and Secondary Electron Emission in Plane-Parallel Plasma Discharge • Stainless steel electrodes • Mean discharge current determined by voltage drop over R • Breakdown voltage is mean value recorded from Oscil. • Copper anode and SS cathode • Voltage increased by increments and allowed to settle • Current spikes from 1 nA to hundreds of mirco-amps • Voltage quickly reduced to zero

  24. Technical Background:Measurements • Measurements during flight: • Temperature • Pressure • Humidity • Voltage • Current

  25. Technical Background:Environmental Sensors • Temperature Sensor • Small signal p-n junction diode • Pressure Sensor • Piezoelectric sensor • Humidity Sensor • Capacitive sensing element with on-chip integration

  26. Technical Background:DC to HVDC Converter • An electronic circuit which converts a source of direct current from one voltage to another • Due to the payload size and weight restrictions, the required voltage for discharge is improbable with on-board batteries alone

  27. Technical Background:Current Sensor • Pico ammeter • Voltage drop across resistor • Radio Frequency Interference • Band of frequencies produces upon discharge

  28. Science Requirements:Spark Gap • The gap distance shall be 1mm • The electrodes shall be composed of copper • The electrodes shall be rough and clear of impurities • The electrode configuration shall create a positive corona discharge

  29. Science Requirements:Power and Sensor • The spark gap shall be provided with a maximum of 4.5kV • The payload shall record temperature, pressure, humidity, voltage, and current across the spark gap • The payload shall be fully operational throughout the entire flight profile

  30. Technical Requirements • The ammeter shall have a minimum accuracy to the microamp range • The HVDC shall operate in all environmental conditions • The output voltage of the DC to DC converter shall be controlled through an on-board interface • All data shall be time-stamped and real-time clock must be synced to the payload GPS

  31. Technical Requirements:LaACES • The payload shall not weigh more than 500 grams • The payload shall not exceed 3 oz / in2 on the smallest face • The payload equipment shall cost less than $500 • The payload shall have two holes 17 cm apart running the length of the payload to comply with LaACES management requirements

  32. Project Management:Team Contract • Team Meeting • Disciplinary Action • Communication • Version Control • Decision Making • Team Roles

  33. Project Management: Organization

  34. Change Control & Update Procedures • Changes to this Pre-PDR document shall follow all regulations set by Team Tesla’s contract and only be made after approval by designated representatives from Team Tesla and the LaACES Institution Representative. Document change requests should be sent to Team members and the LaACES Institution Representative and the LaACES Project.

  35. Project Management: Master Schedule

  36. Reference Documents • http://www.phys.tue.nl/FLTPD/invited/veldhuizen.pdf • http://arc.uta.edu/publications/td_files/paniker.pdf • http://www.isesp.org/icesp%20viii%20papers/VIII-ICESP%20PA1-1.pdf • http://fog.ccsf.cc.ca.us/~wkaufmyn/ENGN45/Course%20Handouts/15_ElectricalProps/07_ImpuritiesConductivityConductors.html • http://prb.aps.org/pdf/PRB/v61/i16/p11109_1 • http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4075398 • http://www.jstor.org/stable/10.2307/96578 • http://rspa.royalsocietypublishing.org/content/167/931/580.full.pdf • http://arc.uta.edu/publications/td_files/paniker.pdf • http://www.lorentzcenter.nl/lc/web/2010/424/PROBLEMS/NXP/OverviewWallashspie.pdf • http://www.ce-mag.com/archive/1999/novdec/mrstatic.html • http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD0720090 • http://neon.dpp.fmph.uniba.sk/workgroup/media/documents/microdischarge_1.pdf • http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0430336 • http://prl.aps.org/pdf/PRL/v90/i22/e224801 • http://www.highvoltageconnection.com/articles/corona.pdf • http://www.dtic.mil/dtic/tr/fulltext/u2/a239940.pdf • http://ethesis.nitrkl.ac.in/2875/1/Full_Thesis_Print_04.07.2011.pdf • http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD0720090 • http://www.irispower.com/pdf/newtechpapers/Investigation%20of%20the%20effect%20of%20humidity%20on%20partial%20discharge%20activity%20in%20stator%20windings.pdf • 143.53.36.235:8080/Medical/research/CoronaDischarge.doc • www.haefely.com/pdf/scientific/e1-19.pdf - Switzerland

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