Langmuir Probe Diagnostics with Optical Emission Spectrometry (OES) for Coaxial Line Microwave Plasma

Abstract

The Langmuir probe is a feasible method to measure plasma parameters. However, as the reaction progresses in the discharged plasma, the contamination would be attached to the probe surface and lead to a higher incorrect electron temperature. Then, the electron density cannot be obtained. This paper reports a simple approach to combining the Langmuir probe and the optical emission spectrometry (OES), which can be used to obtain the electron temperature to solve this problem. Even the Langmuir probe is contaminative, the probe current–voltage (I–V) curve with the OES spectra also gives the approximate electron temperature and density. A homemade coaxial line microwave plasma source driven by a 2.45 GHz magnetron was adopted to verify this mothed, and the electron temperature and density in different pressure (40–80 Pa) and microwave power (400–800 W) were measured to verify that it is feasible.

Spectroscopic and electrical characterization of oxygen microwave discharge used for downstream plasma oxidation of Si

“…With such configuration, plasma perturbations are reduced. 3 Moreover, the surface area of the reference electrode, which is in contact with the plasma, is more than 3 Â 10 4 times larger than the probe wire surface. In addition, an electrostatic planar probe made of stainless steel, having a 7 mm diameter collector and a 16 mm diameter guard ring, both biased at À250 V, was used for the measurement of positive ion flux (Г i ) from the ion saturation current (I sat ).…”

“…1 Microwave plasma sources are well known for their performance in terms of creating high densities of reactive species. [2][3][4] However, among the main disadvantages of these microwave systems are that the plasma generation often requires high microwave power, and the size of the plasma reactor is limited by waveguide dimensions. In addition, such sources require an impedance adaptation system that is difficult to automatize.…”

“…High density uniform microwave generated plasma is essential for surface treatments, sterilization and synthesis of nanomaterials to reconcile the increasing specifications required for sophisticated technologies such as electronics, medical engineering, and solar cell industry. 3,4 In order to improve plasma applications, it is essential to understand the chemistry driven by plasma and then control it. Glow discharge plasma consists of a complex combination of charged species (electrons, atomic and molecular ions), neutrals (free radicals, ground and excited-state atoms and molecules) and electromagnetic radiation.…”

Dual-Frequency Microwave Plasma Source Based on Microwave Coaxial Transmission Line

“…The 2450 MHz microwave is transmitted from the generator to the plasma reactor by the waveguide. A waveguide-to-coaxial adapter is designed and installed to guide the microwave from the waveguide into the coaxial transmission line plasma reactor through Port 1 [15]. A custom-made solid-state microwave power source (Wattsine Electronic Technology Co., Ltd. Chengdu China) is used to generate a continuouswave 915 MHz microwave.…”

“…In previous studies, the exciting frequency for dual-frequency plasma sources mostly were mostly radio frequency (RF), such as 13.56 MHz, 27.12 MHz, 320 MHz, 340 kHz, and 40 kHz, and the structures of the plasma reactor are mostly capacitively coupled plasma (CCP) and/or inductively coupled plasma (ICP). In recent years, more and more microwave plasma sources have been proposed and applied [15][16][17][18]. However, dualfrequency microwave plasma sources are rarely investigated.…”