skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Emission and afterglow properties of an expanding RF plasma with nonuniform neutral gas density

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4960326· OSTI ID:1467862

In this, we describe some notable aspects of the light emission and afterglow properties in pulsed, high-density (1018–1020 m-3) argon inductively coupled discharges initiated following fast gas injection. The plasma was created in a long, narrow discharge tube and then expanded downstream of the radiofrequency (RF) antenna into a large chamber. Fast camera images of the expanding plasma revealed a multi-phase time-dependent emission pattern that did not follow the ion density distribution. Dramatic differences in visible brightness were observed between discharges with and without an externally applied magnetic field. These phenomena were studied by tracking excited state populations using passive emission spectroscopy and are discussed in terms of the distinction between ionizing and recombining phase plasmas. Additionally, a method is presented for inferring the unknown neutral gas pressure in the discharge tube from the time-dependent visible and infrared emission measured by a simple photodiode placed near the antenna. In magnetized discharges created with fast gas injection, the downstream ion density rose by Δni ~ 1018 m-3 in the first ~100 μs after the RF power was turned off. The conditions conducive to this afterglow density rise are investigated in detail, and the effect is tentatively attributed to pooling ionization.

Research Organization:
California Institute of Technology (CalTech), Pasadena, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES); National Science Foundation (NSF); Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States)
Grant/Contract Number:
FG02-04ER54755; SC0010471; 1059519
OSTI ID:
1467862
Alternate ID(s):
OSTI ID: 1283418
Journal Information:
Physics of Plasmas, Vol. 23, Issue 8; ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 1 work
Citation information provided by
Web of Science

References (31)

One-dimensional time-dependent fluid model of a very high density low-pressure inductively coupled plasma journal December 2015
Behavior of the ponderomotive effect near gyroresonance journal January 1984
Determination of Ionization Cross Section for Argon Metastable-Metastable Collision by Means of Afterglow Technique journal August 1996
Principles of Plasma Discharges and Materials Processing book January 2005
Study of magnetic helicity injection via plasma imaging using a high-speed digital camera journal February 2002
Fundamentals of Electric Propulasion book July 2008
Bulk plasma properties in the pulsed glow discharge journal August 2003
Electron and metastable densities in parallel‐plate radio‐frequency discharges journal June 1993
The afterglow mystery of pulsed glow discharges and the role of dissociative electron–ion recombination journal January 2007
Thermal instability of electrolytic capacitor bank used for gas puff valve journal August 2002
Direct extraction of coherent mode properties from imaging measurements in a linear plasma column journal August 2013
Kinetics of Ionization-Recombination of a Plasma and Population Density of Excited Ions. I. Equilibrium Plasma journal July 1979
Emission spectroscopy of a pulsed helium-discharge plasma: Transition from the ionizing phase to the recombining phase journal January 1988
Recombination and enhanced metastable repopulation in the argon afterglow journal May 2012
Hydrogen addition to an argon glow discharge: a numerical simulation journal January 2002
Reduction of plasma density in the Helicity Injected Torus with Steady Inductance experiment by using a helicon pre-ionization source journal October 2013
Effects of adding hydrogen to an argon glow discharge: overview of relevant processes and some qualitative explanations journal January 2000
On the jets, kinks, and spheromaks formed by a planar magnetized coaxial gun journal March 2005
Inelastic scattering of low-energy electrons by metastable atoms journal August 1984
Effect of metastable atom reactions on the electron energy probability functions in afterglows journal November 1998
Comparison of electron‐density measurements made using a Langmuir probe and microwave interferometer in the Gaseous Electronics Conference reference reactor journal October 1993
Pulsed glow discharges for analytical applications journal July 2009
Populations in the metastable and the resonance levels of argon and stepwise ionization effects in a low‐pressure argon positive column journal January 1985
Diffusion, De-Excitation, and Ionization Cross Sections for Metastable Atoms. I journal November 1952
Plasma production by helicon waves journal February 1993
Spatially averaged (global) model of time modulated high density argon plasmas
  • Ashida, Sumio; Lee, C.; Lieberman, M. A.
  • Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, Vol. 13, Issue 5 https://doi.org/10.1116/1.579494
journal September 1995
Plasma oscillations in a 6-kW magnetically shielded Hall thruster journal May 2014
High-speed imaging of edge turbulence in NSTX journal December 2003
Growth mechanism of electron density in radio frequency afterglow plasmas journal January 2001
Battery-powered pulsed high density inductively coupled plasma source for pre-ionization in laboratory astrophysics experiments journal July 2015
Fundamentals of Plasma Physics book January 2006

Cited By (1)

Externally Heated Hollow Cathode Arc Plasma Source for Experiments in Plasma Wakefield Acceleration journal September 2019

Similar Records

One-dimensional time-dependent fluid model of a very high density low-pressure inductively coupled plasma
Journal Article · Mon Dec 28 00:00:00 EST 2015 · Journal of Applied Physics · OSTI ID:1467862

Neutral depletion and the helicon density limit
Journal Article · Sun Dec 15 00:00:00 EST 2013 · Physics of Plasmas · OSTI ID:1467862

Self-consistent modeling of DC and microwave nitrogen discharges and their afterglows
Journal Article · Wed Dec 01 00:00:00 EST 2004 · AIP Conference Proceedings · OSTI ID:1467862