86 research outputs found
Revisiting the anomalous rf field penetration into a warm plasma
Radio frequency waves do not penetrate into a plasma and are damped within
it. The electric field of the wave and plasma current are concentrated near the
plasma boundary in a skin layer. Electrons can transport the plasma current
away from the skin layer due to their thermal motion. As a result, the width of
the skin layer increases when electron temperature effects are taken into
account. This phenomenon is called anomalous skin effect. The anomalous
penetration of the rf electric field occurs not only for transversely
propagating to the plasma boundary wave (inductively coupled plasmas) but also
for the wave propagating along the plasma boundary (capacitively coupled
plasmas). Such anomalous penetration of the rf field modifies the structure of
the capacitive sheath. Recent advances in the nonlinear, nonlocal theory of the
capacitive sheath are reported. It is shown that separating the electric field
profile into exponential and non-exponential parts yields an efficient
qualitative and quantitative description of the anomalous skin effect in both
inductively and capacitively coupled plasma.Comment: 44 pages, invited paper at "Nonlocal, Collisionless Phenomena in
Plasma" worksho
Accuracy of the Explicit Energy-Conserving Particle-in-Cell Method for Under-resolved Simulations of Capacitively Coupled Plasma Discharges
The traditional explicit electrostatic momentum-conserving Particle-in-cell
algorithm requires strict resolution of the electron Debye length to deliver
numerical accuracy. The explicit electrostatic energy-conserving
Particle-in-Cell algorithm alleviates this constraint with minimal modification
to the traditional algorithm, retaining its simplicity and ease of
parallelization and acceleration on modern supercomputing architectures. In
this article we apply the algorithm to model a one-dimensional radio-frequency
capacitively coupled plasma discharge relevant to industrial applications. The
energy-conserving approach closely matches the results from the
momentum-conserving algorithm and retains accuracy even for cell sizes up to 8x
the electron Debye length. For even larger cells the algorithm loses accuracy
due to poor resolution of steep gradients in the radio-frequency sheath. This
can be amended by introducing a non-uniform grid, which allows for accurate
simulations with 9.4x fewer cells than the fully resolved case, an improvement
that will be compounded in higher-dimensional simulations. We therefore
consider the explicit energy-conserving algorithm as a promising approach to
significantly reduce the computational cost of full-scale device simulations
and a pathway to delivering kinetic simulation capabilities of use to industry
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