Y.P. Ren

Electron/ion energy loss to discharge walls revised : A case study in low-temperature, thermally nonequilibrium plasmas

Reliable calculations of the electron/ion energy losses in low-pressure thermally nonequilibrium low-temperature plasmas are indispensable for predictive modeling related to numerous applications of such discharges. The commonly used simplified approaches to calculation of electron/ion energy losses to the chamber walls use a number of simplifying assumptions that often do not account for the details of the prevailing electron energy distribution function (EEDF) and overestimate the contributions of the electron losses to the walls. By direct measurements of the EEDF and careful calculation of contributions of the plasma electrons in low-pressure inductively coupled plasmas, it is shown that the actual losses of kinetic energy of the electrons and ions strongly depend on the EEDF. It is revealed that the overestimates of the total electron/ion energy losses to the walls caused by improper assumptions about the prevailing EEDF and about the ability of the electrons to pass through the repulsive potential of the wall may lead to significant overestimates that are typically in the range between 9 and 32%. These results are particularly important for the development of power-saving strategies for operation of low-temperature, low-pressure gas discharges in diverse applications that require reasonably low power densities.

Inductively Coupled Plasma-Assisted RF Magnetron Sputtering Deposition of Highly Uniform SiC Nanoislanded Films

A new deposition technique - inductively coupled plasma-assisted RF magnetron sputtering has been developed to fabricate SiC nanoislanded films. In this system, the plasma production and magnetron sputtering can be controlled independently during the discharge. The deposited SiC nanoislanded films are highly uniform, have excellent stoichiometry, have a typical size of 10-45 nm, and contain small (~6 nm) cubic SiC nanocrystallites embedded in an amorphous SiC matrix.

Transition radiation energy loss in inductively coupled argon plasma

This work studies the transition radiation energy loss in inductively coupled argon plasma. Energy loss channels due to ionization, momentum transfer, and radiation are investigated in argon plasma bounded by a cylindrical metal vessel. Radiation energy is calculated using the electron energy distribution function diagnosed by a Langmuir probe and the emission cross section. The measured electron energy is found to feature a Druyvesteyn-like distribution. Detailed emission lines and their relative intensity are investigated using high resolution optical emission spectroscopy. Radiation energy loss due to the blue lines (mainly 5p→4s transition) and red-IR lines (4p→4s transition) appears less prominent than that of the two ultraviolet emission lines originated from the transitions of the two lowest resonant levels to the ground state. Approximately 30% collisional energy loss is responsible for ionization, whereas only a few percent of the energy loss is attributed to elastic collision. Most energy loss i...

Hydrocarbon Plasma for Treatment of Biodegradable Food Containers

A newly developed middle-frequency (2 MHz) inductively coupled plasma (ICP) source with internal oscillating current is used to treat biodegradable food packaging surfaces. Initially hydrophilic packaging turns to hydrophobic after being processed by ICP. The investigation of optical emission from hydrocarbon radicals in the Ar/CH4 plasma helps us to understand the property of the hydrophobicity of the surfaces.