Particle-in-Cell Simulations With Fluid Metastable Atoms in Capacitive Argon Discharges : Electron Elastic Scattering and Plasma Density Profile Transition

• Particle-in-cell/Monte Carlo collision (PIC/MCC) simulations are an important tool for understanding low-temperature plasma dynamics, and benchmark work is needed to build a solid base for the correctness of PIC/MCC codes. In our recent publication (Wen et al., 2021), benchmarking of the object-oriented PIC/MCC oopd1 code was performed against the well-established xpdp1 code for a simplified argon reaction set. Furthermore, oopd1 was upgraded to incorporate the excited state atoms as space- and time-varying fluids. Here, we show more details and perform further analysis of the benchmark work. The plasma density profile transition is further explored; the 'passively' flat plasma density profile in the absence of metastables is found to be parabolic at low pressure and flat at 1.6 and 5 Torr. In the presence of metastable atoms, the 'parabolic' profile at 5 Torr becomes 'flat' at 15 Torr due to the reduced excited state atom density in the discharge center, which decreases the step-wise ionization rates. In addition, the effects of electron elastic scattering, i.e., Coulomb-screening-based non-isotropic scattering, total elastic (and momentum transfer) cross-section-dependent non-isotropic scattering, and momentum transfer isotropic scattering on capacitive discharges, are examined, showing that at a low pressure of 50 mTorr Coulomb-screening-based scattering underestimates the plasma density and electron power absorption by around 15%. However, isotropic scattering and cross-section-dependent non-isotropic scattering give almost the same plasma density and electron power absorption. At a higher pressure of 1.6 Torr, the plasma properties are independent of electron scattering in the presence of metastable atoms. In the absence of metastable atoms, different electron scattering treatments bring a few percent difference for plasma density and electron power absorption. 

Ämnesord

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

Nyckelord

Axial plasma density profile transition

Coulomb screening

electron elastic scattering

isotropic and non-isotropic scattering

particle-in-cell/Monte Carlo collisions (PIC/MCCs)

treating neutrals as a space- and time-varying fluid

Argon

Atoms

Codes (symbols)

Collisional plasmas

Dynamics

Electron scattering

Electrons

Excited states

Plasma density

Plasma diagnostics

Plasma simulation

Temperature

Code

Density profile

Discharge (electric)

Isotropics

Monte Carlo collision

Non-isotropic scatterings

Particle in cell

Particle-in-cell/monte carlo collision

Space and time

Time varying

Treating neutral as a space- and time-varying fluid.

Electric discharges

Publikations- och innehållstyp

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