DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Optical emission spectroscopy and imaging of low-pressure N2 plasmas generated by intense fast-pulsed electron beams

Journal Article · · Physics of Plasmas
DOI: https://doi.org/10.1063/5.0241731 · OSTI ID:2510885

An optical emission spectroscopic (OES) and imaging characterization is conducted on N2 plasmas generated by a 100 keV fast-pulsed electron beam. The electron beams are injected into an N2 gas filled volume with a current of 4.5 kA (300 A/cm2) and a 100 ns pulse width. The characterization is conducted at the pressures, 1 Torr and 0.1 Torr, corresponding to two distinct regimes that exhibit significantly different plasma dynamics. Beam impact ionization is shown to be a primary mechanism for producing low temperature plasmas at 1 Torr during beam output. After beam termination, ionization by an inductive electric field becomes the primary mechanism for plasma formation later in time for both pressures. OES and plasma imaging are used in this work as a diagnostic tool to track the distribution of electronic, vibrational, and rotational state transitions and ionized species. This is achieved with the use of a multi-resolution suite of spectrometers capable of acquiring time-resolved spectra. Vibrational and rotational bands of the N2 second positive system (C3Πu→B3Πg) and the N2+ first negative system (B2Σu+→X2Σg+) are identified in both regimes as well as N+ states exclusively in the lower pressure regime. Vibrational and rotational spectra are shown to track the evolution of the time-varying plasma current. Plasma imaging also reveals spatially nonuniform plasma emission at 0.1 Torr. A few hundred shots are recorded to fully characterize the emissions, and results are shown to be highly reproducible (≤±1% with 2σ confidence).

Sponsoring Organization:
USDOE
Grant/Contract Number:
NONE; NA0003525
OSTI ID:
2510885
Journal Information:
Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 2 Vol. 32; ISSN 1070-664X
Publisher:
American Institute of PhysicsCopyright Statement
Country of Publication:
United States
Language:
English

References (44)

Particle beams in the solar atmosphere: General overview journal December 1990
Investigation of an Electromagnetic Pulse Generated by a System on a Standard Spacecraft journal September 2005
Review of industrial applications of electron accelerators journal June 1996
Electron diatomic molecule weighted total cross section calculation journal January 1982
Optical emission spectroscopy of Ar–N2 mixture plasma journal October 2007
Microbial decontamination of food by electron beam irradiation journal July 2015
The dissociative recombination of vibrationally excited N2+ ions journal September 1980
Carbon velvet field-emission cathode journal December 2002
Radiative Lifetime of N2(a 1Πg) and the Formation of Metastable N2(a′ 1Σu−) journal May 1972
Excitation of emission lines of atomic nitrogen ions by electron-impact dissociative ionization of nitrogen molecules journal December 1988
Electron temperatures in a pulsed electric discharge and the associated N2 electron excitation rate coefficients journal January 1991
Recombination of N+4 ions with electrons journal November 1991
Dissociative recombination and excitation of N2+: Cross sections and product branching ratios journal February 1998
Optimizing the emission, propagation, and focusing of an intense electron beam journal May 2015
Modeling nitrogen plasmas produced by intense electron beams journal May 2016
Cross Sections for Collisions of Electrons and Photons with Nitrogen Molecules journal July 1986
The theory and simulation of relativistic electron beam transport in the ion-focused regime journal May 1992
Modeling intense-electron-beam generated plasmas using a rigid-beam approximation journal September 2021
Electron beam impact parameters for the creation of excited species in N2 gas journal June 2023
Perveance and the Bennett Pinch Relation in Partially-Neutralized Electron Beams† journal August 1958
Excitation of vibrational and electronic states in a glow discharge column in flowing N2 journal May 1983
Spectroscopic diagnostics of glow discharge plasmas with non-Maxwellian electron energy distributions journal October 1994
A time-dependent analysis of the nitrogen afterglow in and - Ar microwave discharges journal August 1997
A study by emission spectroscopy of the active species in pulsed DC discharges journal November 1997
Role of long-lived N 2 (X 1 Σ g + , v ) molecules and N 2 (A 3 Σ u + ) and N 2 (a' 1 Σ u - ) states in the light emissions of an N 2 afterglow journal June 2001
On the influence of metastable reactions on rotational temperatures in dielectric barrier discharges in He-N2mixtures journal June 2001
N2+/N2ratio and temperature measurements based on the first negative N2+and second positive N2overlapped molecular emission spectra journal July 2004
Two N2+(B2 u+) populations with different Boltzmann distribution of the rotational levels found in different types of N2/Ar discharges—improved estimation of the neutral gas temperature journal July 2004
Determination of the vibrational, rotational and electron temperatures in N 2 and Ar–N 2 rf discharge journal February 2007
Optical emission spectroscopy as a diagnostic for plasmas in liquids: opportunities and pitfalls journal March 2010
Gas temperature determination from rotational lines in non-equilibrium plasmas: a review journal April 2014
Vibrational Excitation of N 2 , CO, and H 2 by Electron Impact journal August 1964
Anisotropic scattering of electrons by N 2 and its effect on electron transport journal May 1985
Excitation of Several Important Metastable States ofN2by Electron Impact journal February 1972
Absolute cross sections for electron-impact excitation ofN2+ journal June 1974
Electron density measurements on radiographic diodes conference June 2007
On the electromagnetic pulse produced by nuclear explosions journal January 1978
Electron beam lithography in nanoscale fabrication: recent development journal April 2003
State of the Art in IEMP and SGEMP Calculations journal January 1975
Applications of electron-beam generated plasmas to materials processing journal April 2005
Breit-Pauli energy levels and transition rates for the carbonlike sequence journal August 2001
Characterization and Application of Materials Grown by Electron-Beam-Induced Deposition journal December 1994
Electron Beam Generated Plasmas for Ultra Low T e Processing journal January 2015
Self-Focusing of a Pulsed High-Intensity Electron Beam in a Low-Pressure Gas journal March 1979