# Electric field filamentation and higher harmonic generation in a very high frequency capacitive discharges

## TL;DR

This study uses PIC simulations to explore how increasing discharge voltage in high-frequency capacitive plasmas causes electric field filamentation, generates higher harmonics, and affects plasma properties.

## Contribution

It reveals the relationship between discharge voltage and electric field filamentation, harmonic generation, and plasma parameter evolution in high-frequency capacitive discharges.

## Key findings

- Electric field filamentation increases with voltage.
- Higher harmonics up to 7th are observed and grow with voltage.
- Plasma density increases non-linearly, electron temperature decreases.

## Abstract

The effects of the discharge voltage on the formation and nature of electric field transients in a symmetric, collisionless, very high frequency, capacitively coupled plasma are studied using a self-consistent particle-in-cell (PIC) simulation code. At a driving frequency of 60 MHz and 5 mTorr of argon gas pressure, the discharge voltage is varied from 10V to 150 V for a fixed discharge gap. It is observed that an increase in the discharge voltage causes filamentation in the electric field transients and to create multiple higher harmonics in the bulk plasma. Correspondingly, higher harmonics, up to 7th harmonic, in the discharge current are also observed. The power in the higher harmonics increases with a rise in the discharge voltage. The plasma density continues to increase with the discharge voltage but in a non-linear manner, whereas, the bulk electron temperature decreases. Meanwhile, the electron energy distribution function (EEDF) evolves from a Maxwellian at lower discharge voltages to a bi-Maxwellian at higher discharge voltages.