Ph .D. Thesis by Gua-qiang ZHU Toulouse University ,2012
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MODELING OF PLASMA DYNAMICS AND PATERN FORMATION DURING HIGH PRESSURE MICROWAVE BREAKDOWN IN THE AIR Ph.D. Thesis by Gua-qiang ZHU Toulouse University,2012 Presented by Mehmet Serhan Yıldız 28 November 2013 Boğaziçi University, İstanbul
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Modeling of plasma dynamics and patern formation during high pressure microwave breakdown in the air. Presented by Mehmet Serhan Yıldız 28 November 2013 Boğaziçi University , İstanbul. Ph .D. Thesis by Gua-qiang ZHU Toulouse University ,2012. Content. Gas Breakdown - PowerPoint PPT Presentation
Transcript of Ph .D. Thesis by Gua-qiang ZHU Toulouse University ,2012
MODELING OF PLASMA DYNAMICS AND PATERN FORMATION DURING
HIGH PRESSURE MICROWAVE BREAKDOWN IN THE AIR
Ph.D. Thesis by Gua-qiang ZHU Toulouse University,2012
Presented by Mehmet Serhan Yıldız28 November 2013
Boğaziçi University, İstanbul
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CONTENT Gas Breakdown
Gas Breakdown History
Types of Gas Discharge
High Pressure Microwave Discharge
Numerical Method
Results
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GAS BREAKDOWN
R
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Gas Discharges
Non Self Sustaining
Self Sustaining
Break down
Sustaining non
equiblirium
SustainingEquiblirium
DC low freq.and pulsed
Radio freq.
microwave
Optical fields
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GAS BREAKDOWN HİSTORY 17 th century Coulomb proved
experimentally in that charge leaks through air.
19th century first vacuum tube experiment by Faraday (P=1 torr, V=1000V)
In 1889 Friedrich Paschen published his work in which he investigated the minimum potential that is necessary to generate a spark in the gap between the two electrodes in gas discharge tubes.
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GAS BREAKDOWN HİSTORY
Figure.1 Paschen Curve for Air [1]
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GAS BREAKDOWN HİSTORY
At the begining of 1900 Townsend explain development of current in the gas.
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GAS BREAKDOWN HISTORY The discharge phenomenon in microwave field
was first extensively investigated in the late 1940s in order to solve the problem of discharge formation within a waveguide in a radar system.
The free located microwave discharges that are considered in this thesis work were first observed during the 1980s.
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HIGH PRESSURE MICROWAVE BREAKDOWN
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HIGH PRESSURE MICROWAVE BREAKDOWN Diffusive discharge doesn’t absorb microwave
energy due to lower electron neutral momentum transfer frequency.
Streamer form is characterized by high energy coupling.
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HIGH PRESSURE MICROWAVE BREAKDOWN
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HIGH PRESSURE MICROWAVE BREAKDOWN
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NUMERİCAL MODELIonization Frequency
Attachment Frequency Diffusion Cofficient
Electron İon recombination
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Free Diffusion
Ambipolar Diffusion
AmbientPlasma Density Goes to Zero
Plasma Dimensions < Deby Length Free Diffusion
Plasma Dimensions >= Deby Length
Ambipolar Diffusion
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NUMERİCAL MODEL
Debye Length
Chracteristic Length
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NUMERİCAL MODEL
nJ
u
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NUMERİCAL MODEL
Critical Field ionization balance attachment
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RESULTS
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RESULTS
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RESULTS
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REFERENCES
Characterization of Paschen Curve Anomalies at High P*D values W.J.Carey et.al ARC tech.USA
Paschen Test in Superconducting Coils,Knaster J.,IEEE transaction on applied superconductivity,vol.22,No.3,June 2012
