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Title: Broadband microwave characteristics of a novel coaxial gridded hollow cathode argon plasma

Abstract

The interaction between microwave and large area plasma is crucially important for space communication. Gas pressure, input power, and plasma volume are critical to both the microwave electromagnetic wave phase shift and electron density. This paper presents a novel type of large coaxial gridded hollow cathode plasma having a 50 cm diameter and a 40 cm thickness. Microwave characteristics are studied using a microwave measurement system that includes two broadband antennae in the range from 2 GHz to 18 GHz. The phase shift under varying gas pressure and input power is shown. In addition, the electron density n{sub e}, which varies from 1.2 × 10{sup 16} m{sup −3} to 8.7 × 10{sup 16} m{sup −3} under different discharge conditions, is diagnosed by the microwave system. The measured results accord well with those acquired by Langmuir Probe measurement and show that the microwave properties in the large volume hollow cathode discharge significantly depend on the input power and gas pressure.

Authors:
; ; ; ; ;  [1];  [1];  [2];  [3]
  1. Department of Physics, Harbin Institute of Technology, Harbin 150001 (China)
  2. (LEME), China Research Institute of Radio Wave Propagation, Beijing 102206 (China)
  3. National Key Laboratory of Electromagnetic Environment (LEME), China Research Institute of Radio Wave Propagation, Beijing 102206 (China)
Publication Date:
OSTI Identifier:
22597681
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 87; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANTENNAS; ARGON; DIAGNOSIS; ELECTRON DENSITY; ELECTRONS; GHZ RANGE 01-100; HOLLOW CATHODES; LANGMUIR PROBE; MICROWAVE RADIATION; PHASE SHIFT; PLASMA; THICKNESS

Citation Formats

Gao, Ruilin, Yuan, Chengxun, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn, Jia, Jieshu, Zhou, Zhong-Xiang, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn, Wang, Ying, Wang, Xiaoou, Li, Hui, National Key Laboratory of Electromagnetic Environment, and Wu, Jian. Broadband microwave characteristics of a novel coaxial gridded hollow cathode argon plasma. United States: N. p., 2016. Web. doi:10.1063/1.4960393.
Gao, Ruilin, Yuan, Chengxun, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn, Jia, Jieshu, Zhou, Zhong-Xiang, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn, Wang, Ying, Wang, Xiaoou, Li, Hui, National Key Laboratory of Electromagnetic Environment, & Wu, Jian. Broadband microwave characteristics of a novel coaxial gridded hollow cathode argon plasma. United States. doi:10.1063/1.4960393.
Gao, Ruilin, Yuan, Chengxun, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn, Jia, Jieshu, Zhou, Zhong-Xiang, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn, Wang, Ying, Wang, Xiaoou, Li, Hui, National Key Laboratory of Electromagnetic Environment, and Wu, Jian. Mon . "Broadband microwave characteristics of a novel coaxial gridded hollow cathode argon plasma". United States. doi:10.1063/1.4960393.
@article{osti_22597681,
title = {Broadband microwave characteristics of a novel coaxial gridded hollow cathode argon plasma},
author = {Gao, Ruilin and Yuan, Chengxun, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn and Jia, Jieshu and Zhou, Zhong-Xiang, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn and Wang, Ying and Wang, Xiaoou and Li, Hui and National Key Laboratory of Electromagnetic Environment and Wu, Jian},
abstractNote = {The interaction between microwave and large area plasma is crucially important for space communication. Gas pressure, input power, and plasma volume are critical to both the microwave electromagnetic wave phase shift and electron density. This paper presents a novel type of large coaxial gridded hollow cathode plasma having a 50 cm diameter and a 40 cm thickness. Microwave characteristics are studied using a microwave measurement system that includes two broadband antennae in the range from 2 GHz to 18 GHz. The phase shift under varying gas pressure and input power is shown. In addition, the electron density n{sub e}, which varies from 1.2 × 10{sup 16} m{sup −3} to 8.7 × 10{sup 16} m{sup −3} under different discharge conditions, is diagnosed by the microwave system. The measured results accord well with those acquired by Langmuir Probe measurement and show that the microwave properties in the large volume hollow cathode discharge significantly depend on the input power and gas pressure.},
doi = {10.1063/1.4960393},
journal = {Review of Scientific Instruments},
number = 8,
volume = 87,
place = {United States},
year = {Mon Aug 15 00:00:00 EDT 2016},
month = {Mon Aug 15 00:00:00 EDT 2016}
}
  • This paper reports a novel coaxial gridded hollow discharge during operation at low pressure (20 Pa–80 Pa) in an argon atmosphere. A homogeneous hollow discharge was observed under different conditions, and the excitation mechanism and the discharge parameters for the hollow cathode plasma were examined at length. An optical emission spectrometry (OES) method, with a special focus on absolute continuum intensity method, was employed to measure the plasma parameters. The Langmuir probe measurement (LPM) was used to verify the OES results. Both provided electron density values (n{sub e}) in the order of 10{sup 16} m{sup −3} for different plasma settings. Taken together, themore » results show that the OES method is an effective approach to diagnosing the similar plasma, especially when the LPM is hardly operated.« less
  • A new model of the microwave-boosted hollow cathode lamp has been devised, giving considerable improvement in the coupling efficiency of the two types of discharges. For this to be achieved, a resonant cavity is interposed between the cathodic and anodic blocks of the demountable tube, causing the microwave field to interact with the plasma inside the cathode. The performance of this potentiated lamp has been tested discharging a number of elements (Al, C, Cu, Fe, Mo, and Ni). In all instances there was a significant increase in intensity of the emitted spectra, together with a noticeable diminution of background; thusmore » signal-to-background ratios of even two orders of magnitude higher than those obtainable by conventional hollow cathode discharge lamps were achieved. An additional advantage of this combined lamp is its high stability of operation.« less
  • Velocity analysis of the molecular beam is done with a time-of-flight method. The measured velocity distribution of the fast neutral atoms is described by the sum of two Maxwell-Boltzmann distributions with temperatures on the order of 0.25 and 1 eV, respectively. This bimodal distribution is attributed to an overpopulation of the high-energy tail of the ion velocity distribution. The measured intensities of the fast neutrals vary between 5 x 10/sup 14/ and 7 x 10/sup 15/ (molecules s/sup -1/ sr/sup -1/).
  • Two nonconventional systems, the radio frequency hollow cathode discharge (RHCD) and the microwave antenna discharge (MWAD), with almost identical geometry of electrodes generating a nitrogen plasma at power level up to 60 W were compared. Both systems were used for deposition of nitride films at similar experimental parameters. The Al--N films were deposited in the RHCD system by reactive physical vapor deposition (PVD) using an Al radio frequency hollow cathode and the CN{sub x} films were deposited in the MWAD system by plasma activated chemical vapor deposition (PACVD) from N{sub 2}+1% (alternatively 0.5% or 0.4%) C{sub 2}H{sub 2} gas mixtures.more » The vibrational temperatures of nitrogen molecules in both systems were compared as functions of experimental parameters and discussed with respect to the film growth rates in the particular systems. It was found that irrespective of frequency difference of two orders of magnitude the vibrational temperatures of nitrogen molecules were similar, between 3000 and 4600 K, in both systems at similar experimental conditions. However, shapes of dependences of the vibrational temperature on particular parameters were different, due to different plasma generation principles. The nitride film growth rates were found to correlate to the vibrational temperatures of nitrogen molecules, but their dependences on experimental parameters were affected by specific features of the plasma generation in individual systems as well as by different mechanisms of the PVD and the PACVD of films. {copyright} 2001 American Institute of Physics.« less
  • The formation of electron emission-bias voltage (I-V) characteristics of near-zero differential resistance in the cathodic plasma contactor for bare electrodynamic tether applications, based on a hollow cathode embedded in a ring-cusp ionization stage, is studied. The existence of such an I-V regime is important to achieve low impedance performance without being affected by the space plasma properties for a cathodic plasma contactor. Experimental data on the plasma structure and properties downstream from the ionization stage are presented as functions of the xenon flow rate and the electron emission current. The electrons were emitted from the cathode to the cylindrical vacuummore » chamber wall (r = 0.9 m) under ≈10{sup −5 }Torr of vacuum pressure. The ring-cusp configuration selected for the plasma contactor created a 125-Gauss axial field near the cathode orifice, along with a large-volume 50-Gauss magnitude pocket in the stage. A baseline ion energy cost of ≈300 eV/ion was measured in the ionization stage when no electrons were emitted to the vacuum chamber wall. In addition, the anode fall growth limited the maximum propellant unitization to below ≈75% in the discharge loss curves for this ion stage. Detailed measurements on the plasma properties were carried out for the no-electron emission and 3 A emission conditions. The experimental data are compared with 1-D models, and the effectiveness of the model is discussed. The four key issues that played important roles in the process of building the near-zero different resistance I-V regime are: a significant amount of ionization by the emission electrons, a decrease in the number of reflected electrons in the plume, the electron-temperature increment, and low initial ion energy at the source outlet.« less