Abnormal Heating of Low-Energy Electrons in Low-Pressure Capacitively Coupled Discharges

Abstract

In low-pressure capacitively coupled plasmas, high-energy electrons are collisionlessly heated by large rf fields in the sheaths while low-energy electrons are confined in the bulk plasma by the ambipolar potential. Low-energy electrons are typically inefficiently heated due to their low collisionality and the weak rf electric field present in the bulk. It is shown, however, that as a result of the nonlinear interaction between the electron motion and the weak rf field present in the bulk, low-energy electrons can be efficiently heated. Electrons in the bulk that bounce inside the electrostatic potential well with a frequency equal to the rf excitation frequency are efficiently heated by the coherent interaction with the rf field. This resonant collisionless heating can be very efficient and manifest itself as a plateau in the electron energy probability function.

Optimization of Operating Parameters of Plasma Antenna

“…These features are mostly including the nonlocal plasma kinetic effects, Ohmic heating, and striation formation inside the plasma antenna [19,20,21]. On the other hand, the differential cross sections for collisions, that are essential in the plasma antenna, can be easily implemented in the PIC-MCC simulation schemes.…”

“…Source terms for the field equations are accumulated from the particle locations to the grid locations. The field values are then advanced by one time-step, and the time loop starts again ( Figure 2) [19,24,25,28,30]. In the PIC-MCC simulation scheme, each super-particle, representative of one or a much larger number of real particles, is designated in continuum space by its position and velocity.…”

Electron and Ion Kinetics in a DC Microplasma at Atmospheric Pressure

“…In this paper, a current-driven atmospheric-pressure helium microdischarge is simulated using a 1-D particle-in-cell Monte Carlo collision (PIC-MCC) model. This model can capture fundamental plasma physics that cannot be simulated with fluid models such as nonlocal plasma kinetics, collisionless heating, and striation formation [13]- [16]. The PIC-MCC simulation results are compared, when possible, with the fluid simulation results that are reported in [2].…”

Electron heating in radio-frequency capacitively coupled atmospheric-pressure plasmas

“…These sources eliminate the need for costly vacuum systems 4-6 and have potential application in scientific/ industrial fields where vacuum operation is not practical, e.g., biomedicine. 7,8 In contrast to low-pressure discharges where nonlocal electron kinetics, 1,9 collisionless heating, 1,2,10 and bounced resonant motion 11 can play important roles, atmospheric-pressure discharges tend to operate in the local regime and are dominated by collisional ͑Ohmic͒ heating. This is so because L / v th ӷ 1 and Ӷ L are typically satisfied.…”