Particle in cell modelling of the observed modes of a dc wire discharge

R Gueroult (1, 2) , P Q Elias (1) , D Packan (1) , J Bonnet (1) , Jean-Marcel Rax (2)

1 ONERA - The French Aerospace Lab [Palaiseau]
2 X - École polytechnique

Low pressure DC Wire Induced Plasma Sources (WIPS) exhibit two stable modes of discharge- constricted below a threshold pressure and diffuse above. Starting from experimental measurements, we conduct two dimensional particle in cell (PIC) modelling of a DC low pressure (10 −4 − 10 −2 mbar), low current (∼ 1 mA) wire discharge in Helium. 2D PIC modelling is required to capture longitudinal non uniformity of the diffuse mode. PIC simulations reproduce the two discharge modes. Voltage versus pressure curve obtained from simulations matches fairly well experimental data, including the transition region. Discharge voltage dependence on pressure is analysed in consideration of electron impact ionization rates evolution with energy. In light of the PIC findings, a model of the discharge mode transition based on a Child Langmuir theory for ions is proposed. Confrontation with simulated data shows good agreement and validate the model for mode transition prediction. Simulations show that the diffuse mode is a space charge dominated regime.

Mots clés: Physical Sciences

R Gueroult, P Q Elias, D Packan, J Bonnet, Jean-Marcel Rax. Particle in cell modelling of the observed modes of a dc wire discharge. Journal of Physics D: Applied Physics, 2010, 43 (36), pp.365204. ⟨10.1088/0022-3727/43/36/365204⟩. ⟨hal-00569695⟩