Comparison of measurements and particle-in-cell simulations of ion energy distribution functions in a capacitively coupled radio-frequency discharge
- National Centre for Plasma Science and Technology (NCPST), Dublin City University, Dublin (Ireland)
The ion dynamics in the high-voltage sheath of a capacitively coupled radio-frequency plasma has been investigated using mass-resolved ion energy analysis in combination with a two-dimensional particle-in-cell (PIC) code. A symmetric confined discharge is designed allowing highly accurate comparisons of measured ion energy distribution functions in high-voltage sheaths with simulation results. Under the conditions investigated, the sheaths are not only collisional, but also chemically complex. This situation is common in applications but rare in laboratory experiments. Excellent agreement has been found for a hydrogen discharge benchmarking the code. Hydrogen is of particular interest since its light mass gives detailed insight into sheath dynamics, and an extensive database of collisional cross sections is available. The H{sub 3}{sup +} ion was found to be the dominant ion in the sheaths and the plasma bulk under most conditions investigated. H{sub 3}{sup +} exhibits the typical saddle-shaped ion energy distribution function indicative of ions created in the plasma bulk and traversing the entire sheath potential. H{sup +} and H{sub 2}{sup +} are predominantly formed through collisions in the high-voltage sheath. H{sub 2}{sup +} ion energy distribution functions show structures resulting from symmetric charge exchange collisions with the background gas. Minor discrepancies between the experimental results and PIC simulations indicate slightly lower plasma densities in the simulation, resulting in larger sheath width.
- OSTI ID:
- 21062058
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 10 Vol. 14; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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COLLISIONS
COMPARATIVE EVALUATIONS
ELECTRIC POTENTIAL
ELECTRON TEMPERATURE
ENERGY SPECTRA
HIGH-FREQUENCY DISCHARGES
HYDROGEN IONS 1 PLUS
HYDROGEN IONS 2 PLUS
HYDROGEN IONS 3 PLUS
ION TEMPERATURE
PLASMA
PLASMA DENSITY
PLASMA SHEATH
PLASMA SIMULATION
RADIOWAVE RADIATION
TWO-DIMENSIONAL CALCULATIONS