High energy negative ion generation by Coulomb implosion mechanism

2009 ◽  
Vol 16 (11) ◽  
pp. 113106 ◽  
Author(s):  
T. Nakamura ◽  
Y. Fukuda ◽  
A. Yogo ◽  
M. Tampo ◽  
M. Kando ◽  
...  
Keyword(s):  
High Energy ◽  
Negative Ion ◽  
Ion Generation

Laser driven high energy ion generation for a compact cancer therapy accelerator

2003 ◽  
Author(s):  
Koji Matsukado ◽  
Hiroyuki Daido ◽  
Zhong Li ◽  
Atsushi Fukumi ◽  
Yukio Hayashi ◽  
...  
Keyword(s):  
Cancer Therapy ◽  
High Energy ◽  
Ion Generation

Effect of high energy electrons on H−production and destruction in a high current DC negative ion source for cyclotron

2016 ◽  
Vol 87 (2) ◽  
pp. 02B127 ◽  
Author(s):  
M. Onai ◽  
H. Etoh ◽  
Y. Aoki ◽  
T. Shibata ◽  
S. Mattei ◽  
...  
Keyword(s):  
High Energy ◽  
Ion Source ◽  
Negative Ion ◽  
High Current ◽  
High Energy Electrons

Global model analysis of negative ion generation in low-pressure inductively coupled hydrogen plasmas with bi-Maxwellian electron energy distributions

2015 ◽  
Vol 22 (3) ◽  
pp. 033506 ◽  
Author(s):  
Sung-Ryul Huh ◽  
Nam-Kyun Kim ◽  
Bong-Ki Jung ◽  
Kyoung-Jae Chung ◽  
Yong-Seok Hwang ◽  
...  
Keyword(s):  
Electron Energy ◽  
Low Pressure ◽  
Model Analysis ◽  
Global Model ◽  
Negative Ion ◽  
Energy Distributions ◽  
Inductively Coupled ◽  
Hydrogen Plasmas ◽  
Ion Generation

Hybrid simulation of instabilities in capacitively coupled RF CF4/Ar plasmas

2022 ◽  
Author(s):  
Wan Dong ◽  
Yi Fan Zhang ◽  
ZhongLing Dai ◽  
Julian Schulze ◽  
Yuan-Hong Song ◽  
...  
Keyword(s):  
Electric Field ◽  
Electron Temperature ◽  
Electron Impact ◽  
Electron Density ◽  
Etching Rate ◽  
Reaction Rates ◽  
High Energy ◽  
Density Fluctuations ◽  
Negative Ion ◽  
Capacitively Coupled

Abstract Radio frequency capacitively coupled plasmas (RF CCPs) sustained in fluorocarbon gases or their mixtures with argon are widely used in plasma-enhanced etching. In this work, we conduct studies on instabilities in a capacitive CF4/Ar (1:9) plasma driven at 13.56 MHz at a pressure of 150 mTorr, by using a one-dimensional fluid/Monte-Carlo (MC) hybrid model. Fluctuations are observed in densities and fluxes of charged particles, electric field, as well as electron impact reaction rates, especially in the bulk. As the gap distance between the electrodes increases from 2.8 cm to 3.8 cm, the fluctuation amplitudes become smaller gradually and the instability period gets longer, as the driving power density ranges from 250 to 300 W/m2. The instabilities are on a time scale of 16-20 RF periods, much shorter than those millisecond periodic instabilities observed experimentally owing to attachment/detachment in electronegative plasmas. At smaller electrode gap, a positive feedback to the instability generation is induced by the enhanced bulk electric field in the highly electronegative mode, by which the electron temperature keeps strongly oscillating. Electrons at high energy are mostly consumed by ionization rather than attachment process, making the electron density increase and overshoot to a much higher value. And then, the discharge becomes weakly electronegative and the bulk electric field becomes weak gradually, resulting in the continuous decrease of the electron density as the electron temperature keeps at a much lower mean value. Until the electron density attains its minimum value again, the instability cycle is formed. The ionization of Ar metastables and dissociative attachment of CF4 are noticed to play minor roles compared with the Ar ionization and excitation at this stage in this mixture discharge. The variations of electron outflow from and negative ion inflow to the discharge center need to be taken into account in the electron density fluctuations, apart from the corresponding electron impact reaction rates. We also notice more than 20% change of the Ar+ ion flux to the powered electrode and about 16% difference in the etching rate due to the instabilities in the case of 2.8 cm gap distance, which is worthy of more attention for improvement of etching technology.

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