A 3D numerical analysis on magnetic field enhanced microwave linear plasma

Abstract

Microwave linear plasma has attracted a lot of attention due to the outstanding characteristics such as high electron density, low electron temperature, no-pollution, and homogenization, which can realize a large-area uniform plasma source through vertical or horizontal arrangement especially. In order to explore the effect of the permanent magnets and the microwave coaxial reflective antenna on density and uniformity of plasma, a three-dimensional numerical model is established. It is expected to obtain a superior microwave linear plasma source with high density and uniformity for fabricating a carbon film such as graphene or surface treatment. The results show that (1) permanent magnets can improve the density and uniformity of plasma by generating a suitable magnetic field. At the microwave power of 800 W at 20 Pa, the permanent magnets with 150 kA/m enhance the average electron density by 36.67% and control the relative deviation of electron density within −3% to 1% at an axial distance of 100 mm–300 mm. (2) The reflective antenna can effectively regulate the shape and the uniformity of plasma. The semicylinder reflective antenna realizes the relative deviation of electron density within −2% to 0.5%. Meanwhile, the average electron density increases by 3.75% between an axial distance of 100 mm and 300 mm under a microwave power of 800 W at 20 Pa. (3) The external magnetic field and reflective antenna also have the regulation on heavy particles (Ars) in plasma, which is an important factor for application.

Axial uniformity diagnosis of coaxial surface wave linear plasma by optical emission spectroscopy

“…The compensation of dual microwave powers plays significant role as before. That axial line distribution of electron density was found to have agreement with the previous numerical works in the [22][23][24]. The twodimension and three-dimension models were built to investigate the inner physical process of the coaxial surface linear plasma.…”

“…In this work, the coaxial surface wave linear plasma source ignited by 2.45 GHz microwave powers with length over 600 mm under low pressure is developed, which is an extending for previous numerical simulation research [22][23][24]. Argon plasma parameters under different discharge conditions are measured by optical emission spectroscopy, which is confirmed as a credible plasma diagnostic technology by many researchers [25][26][27][28].…”

Electron cyclotron resonance (ECR) enhanced diverging magnetic field for controlled particle flux in a microwave-excited plasma column – a numerical investigation

“…Finally, a mutual interaction between the ionizing MWs and the ionized plasma will be established, leading to the sustenance of the plasma column [13,18]. This type of discharge has interesting features such as high electron density, good controllability, and uniformity [30]. They are considered beneficial due to (1) their operation for a wider ranges of pressure and gas flow rate, (2) efficient power transfer from the MW to the plasma, and (3) electrodeless working capability.…”

“…The presence of a magnetic field in the plasma can help in increasing the ionization fraction of the medium due to frequent collisions among the particles [30,31]. Plasmas in the presence of a magnetic field show various interesting phenomena such as the pinch effect [32], mirror confinement [32], and atmospheric whistler waves [32] to name a few.…”

An investigation on improving the homogeneity of plasma generated by linear microwave plasma source with a length of 1550 mm

“…It is known that higher productivity can be achieved by improving deposition rate or enlarging equipment size. There have been a few comprehensive works focusing on improving deposition rate, including optimization of the structure and process parameters [14][15][16]. In fact, enlarging the size of the device is supposed to be a more efficient approach.…”