team jupiter
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TEAM JUPITERKATHERINE BLACKBURN· SETH BURLEIGH · JOSEPH
TRAN
LaAces 2009-2010Pre-Preliminary Design
Review
Our goal is to investigate the causes of atmospheric electrical conductivity as a function of altitude. The launch will take place at the Columbia Scientific Balloon Facility (CSBF), in Palestine, Texas on May 25, 2010.
MISSION GOAL
•Alpha Particles-ionizing forms of particle radiation•Aerosols-Small particles made up of atoms which
cling to nuclei in the atmosphere•Cosmic Ray-rays of highly energized particles from space•Humidity-Clouds, haze or other moisture
collection in the atmosphere• Laminar Flow-flow of particles in a uniform direction• Shot Noise-Noise in the voltage measurement due to ions directly striking the inner electrode
DEFINITIONS
• See if there exists any correlations between air conductivity and cosmic ray activity• Show uncharacteristic fluctuations in conductivity due to meteorological
events•Compare general profiles of temperature, pressure, humidity, and altitude with conductivity
SCIENCE GOALS
WHAT IS ATMOSPHERIC ELECTRICAL CONDUCTIVITY?
• The measure of positive and negative ions in the atmosphere• Generally increases with altitude
SCIENCE BACKGROUND
Figure 1- Altitude as a function of conductivity. Most of the potential drop of the atmosphere occurs near the surface. Adapted from Reference 2.
WHAT AFFECTS ATMOSPHERIC ELECTRICAL CONDUCTIVITY?
• Pollution level of air (e.g. aerosols)• Increased radiation in an area (e.g. cosmic
rays on the atmosphere)• Wind, pressure, moisture, and humidity
(i.e. factors that affect ion mobility)
IMPLICATIONS?• Cloud formations• Thunderstorms
SCIENCE BACKGROUND
PAST PROJECTS
• Pollution measurements based on surface conductivity in Mysore, India• Balloon payload in Antarctica (Figure 2)
SCIENCE BACKGROUND
Figure 2 – There is a quasi-sinusoidal behavior of the electrical field with respect to time as shown above. Adapted from Reference 2.
• Must be able to sense small changes to see
uncharacteristic changes from surface to 100,000 feet• Altitude and time must be measured• Cosmic ray intensity and atmospheric
conductivity data needs to be compared for possible correlations
SCIENCE REQUIREMENTS
•Measurement will occur from surface level to 100,000 feet• Target ascent rate is 1000 feet per minute•Altitude, temperature, cosmic ray count, windspeed, and humidity will need to be measured
TECHNICAL GOALS
TECHNICAL BACKGROUND
0 2 4 6 8 10 12 14 16 18 200
5
10
15
20
25
30 Voltage Decay Curves at Various Air Conductivity
5000 fS 800 fS
400fS 100 fS
25 fS
Time (second)
Bias
Vol
tage
THEORY OF OPERATION: VOLTAGE DECAY• Sample 1-2 Hz for 5-20 seconds•Reset Voltage
TECHNICAL BACKGROUND
Equation - Gerdien capacitor current given V (outer voltage- inner voltage), L (length), a (conductivity), b(inner radius), and a (outer radius)
Equation - Critical mobility - the minimum ion mobility (drift velocity/electric field) that will be captured by the gerdien capacitor
Equation 3 – Conductivity vs. exponential fit time constant
Equation 4 – Capacitor current vs. combined Gerdien and measurement capacitance and change in outer-inner cylinder voltage
Equation 5 – Conductivity
Equation 6 – Theoretical cylindrical capacitor capacitance
TECHNICAL BACKGROUNDCRITICAL MOBILITY,
ION CURRENT, BIAS VOLTAGE
• A voltage-sampling rate of 1 hertz (Hz) per 10 seconds (s)
•Memory of 4050 bytes
•At lower conductance (around 100 femtoSiemens) a 12 bit analog to digital converter with a 5 voltage (V)
• The end of the inner electrode must be bullet shaped to promote laminar flow
TECHNICAL REQUIREMENTS
ROLES AND STAFFING PLAN
Table 1 – Staffing PlanCategory: Team Member: Analysis Joseph TranCalibrations Joseph TranData Processing Seth BurleighDocumentation Katherine BlackburnElectronics Seth BurleighFlight Software Joseph TranIntegration Seth BurleighMechanical Seth BurleighProject Management Katherine BlackburnScience Requirements Katherine BlackburnSystem Testing Joseph Tran
1. K. Nagaraja, B.S.N. Prasad, N. Srinivas, M.S. Madhava, Electrical conductivity near the Earth's surface: Ion-aerosol model, Journal of Atmospheric and Solar-Terrestrial Physics, Volume 68, Issue 7, April 2006, Pages 757-768, (http://www.sciencedirect.com/science/ article/ B6VHB-4JDMR5M-1/2/607a27d56c6adbf8ce265ea1ad0d8e0a)
2. E.A. Bering, A.A. Few, J.R. Benbrook, The Global electric circuit, Journal of Physics Today, Volume 51, Issue 10, 1998, Pages 24-30
3. N. Ragini, T.S. Shashikumar, M.S. Chandrashekara, J. Sannappa, L. Paramesh, Temporal and vertical variations of atmospheric electrical conductivity related to radon and its progeny concentrations at Mysore, Indian Journal of Radio & Space Physics, Volume 37, August 2008, Pages 264-271
4. K.L. Aplin, A novel technique to determine atmospheric ion mobility spectra, Journal of Atmospheric and Oceanic Physics, January 2005, (arXiv:physics/0501129v1)
5. K.L. Aplin, Instrumentation for atmospheric ion measurements, University of Reading Department of Meteorology, August 2000, Pages 1-274
REFERENCES (1/2)
6. J.P. Scott and W.H. Evans, The electrical conductivity of clouds, Journal of Pure and Applied Geophysics, Volume 75, Issue 1, December 1969, Pages 219-232 (http://www.springerlink.com/content/x804k7123mqhn3r5/)
7. R.G. Harrison, A.J. Bennett, Cosmic ray and air conductivity profiles retrieved from early twentieth century balloon soundings of the lower troposphere, Journal of Atmospheric and Solar-Terrestrial Physics, Volume 69, November 2006, Pages 515-527
8. K.A. Nicholl, R.G. Harrison, A double gerdien instrument for simultaneous bipolar air conductivity measurements on balloon platforms, Journal of Review of Scientific Instruments, Volume 79, August 2008
9. K.L. Aplin, R.G. Harrison, A computer-controlled gerdien atmospheric ion counter, Journal of Review of Scientific Instruments, Volume 71, Issue 8, August 2000
10. B. Balsey, (2009). Aerosol size distribution . Retrieved from http://cires.colorado.edu/science/groups/balsley/research/aerosol-distn.html
REFERENCES (2/2)
QUESTIONS?
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