Author details
Author's Published Works
Scheduled Maintenance on Monday 1/13/2025
Single article sales and account management will be unavailable from 5:00 AM - 7:00 PM ET (09:00 - 23:00 UTC). We apologize for the inconvenience.
Author details
Showing 1-25 of 29 results
- Sort
Sort By
Results
Theoretical and experimental study of breakdown delay time in pulse discharge
Irina Schweigert;Matthew Hopkins;Edward Barnat;Michael Keidar
2020 29th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV)
Year: 2021 | Conference Paper |
PIC MCC simulation results on the breakdown in the pulse discharge in helium at pressure of 100 Torr and voltage of U=3.25 kV are presented. The delay of the breakdown development is studied with different initial densities of plasma and excited helium atoms, which corresponds to various discharge operation frequencies. It is shown that for high concentration of excited atoms the photoemission det...Show More
Experimental Observations on the Characteristics of an Anode Spot Onset
E. V. Barnat;B. Scheiner;S. D. Baalrud;B.T. Yee;M. M. Hopkins
2018 IEEE International Conference on Plasma Science (ICOPS)
Year: 2018 | Conference Paper |
Experimental observations of the characteristic features of anode spot onset and stabilization in response to a stepped voltage applied to an anode immersed in a low pressure (100 mTorr) helium afterglow are reported in this poster presentation. These observations include spatial and temporal evolution of metastable species measured by planar Laser induced fluorescence (PLIF), electron densities a...Show More
Ionization Wave Propagation and Surface Interactions in a He Plasma Jet
Amanda M. Lietz;John E. Foster;Mark J. Kushner;Edward V. Barnat
2018 IEEE International Conference on Plasma Science (ICOPS)
Year: 2018 | Conference Paper |
The ability of atmospheric pressure plasma jets (APPJs) to produce reactive oxygen and nitrogen species (RONS) for biomedical applications depends on control of the periodic ionization wave (IW) that propagates through the jet into the ambient. When treating surfaces, the need for control extends to the intersection of the IW with and propagation along the surface.Show More
Influence of Photon and Ion Induced Secondary Yields on Transient Plasma Formation
Andrew Fierro;Edward Barnat;Christopher Moore;Paul Clem;Matthew Hopkins
2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV)
Year: 2018 | Conference Paper |
The influence of different quantum yields for photons and secondary emission yields for ions striking a surface is investigated. Using a one-dimensional particle-in-cell simulation, these secondary emission coefficients are varied to observe the impact on discharge current. The discharge is assumed to occur in pure helium gas at a pressure of 75 torr. To handle binary particle interactions, the Di...Show More
Development of Laser-Collision Induced Fluorescence for Atmospheric Pressure Plasma Generated in Helium Atmospheres
2017 IEEE International Conference on Plasma Science (ICOPS)
Year: 2017 | Conference Paper |
The implementation and demonstration of laser-collision induced fluorescence (LCIF) generated in atmospheric pressure helium environments is presented in this communication. As collision times are observed to be fast (~ 10 ns), ultrashort pulse laser excitation (< 100 fs) of the 23S to 33P (388.9 nm) is utilized to initiation the LCIF process. Both neutral induced and electron induced components o...Show More
Characteristics of a High-Pressure Pulsed Arc Discharge Environment
2017 IEEE International Conference on Plasma Science (ICOPS)
Year: 2017 | Conference Paper |
The characteristics and properties of a plasma generated in a pulsed arc discharge are investigated. Arc discharge plasmas are prevalent in the production and treatment of materials. Photodetectors and optical emission spectroscopy (OES) are used to probe the plasmas and characterize their spectral responses. OES allows for species identification and provides information about the state of the pla...Show More
Temporal and spatial dynamics of a bipolar pulsed plasma at audio frequency
Ricky Tang;Edward V Barnat;Matthew M. Hopkins;Paul A. Miller
2016 IEEE International Conference on Plasma Science (ICOPS)
Year: 2016 | Conference Paper |
Summary form only given. Plasmas have been utilized extensively in various processing applications. Both radio-frequency (rf) and pulsed discharges have been employed by the community. We investigated the two methods of plasma generation and observed interesting differences. Optical emission spectroscopy shows higher-intensity emission in the UV/visible range for the pulsed plasma comparing to the...Show More
Theory of sheaths near positively biased electrodes
Brett Scheiner;Scott D. Baalrud;Benjamin T. Yee;Matthew M. Hopkins;Edward V. Barnat
2016 IEEE International Conference on Plasma Science (ICOPS)
Year: 2016 | Conference Paper |
Cited by: Papers (2)
Recent work [1] has shown that electron sheaths, such as those around Langmuir probes collecting the electron saturation current, can affect the bulk plasma through a presheath. Unlike typical ion presheaths, where ions are directly accelerated through an electric field, the electron presheath accelerates electrons to approximately an electron thermal speed through a force due to pressure gradient...Show More
Plasma potential locking
Matthew M. Hopkins;Benjamin T. Yee;Edward V. Barnat;Scott D. Baalrud;Brett Scheiner
2016 IEEE International Conference on Plasma Science (ICOPS)
Year: 2016 | Conference Paper |
Summary form only given. A positively biased electrode (anode) in a plasma is assumed to have no, or little, global impact if the electrode is small enough, i.e., used as a diagnostic probe. For a sufficiently large anode the plasma is globally impacted via plasma potential locking where the anode potential controls the bulk plasma potential. Prior experiments1 and theoretical descriptions2 are ex...Show More
Length scales of the electron sheath and presheath
Benjamin T. Yee;Edward V Barnat;Matthew M. Hopkins;Brett Scheiner;Scott D. Baalrud
2016 IEEE International Conference on Plasma Science (ICOPS)
Year: 2016 | Conference Paper |
Provided a sufficiently small electrode, it is possible to bias it above the plasma potential. This results in an electron sheath, common to Langmuir probes in electron saturation. The traditional understanding of electron sheaths has been that they are isolated from the bulk plasma and result in a truncation of the electron velocity distribution at the sheath edge [1]. Recent results reveal that ...Show More
Development and calibration of electron density measurements in argon plasma using laser collision-induced fluorescence
2016 IEEE International Conference on Plasma Science (ICOPS)
Year: 2016 | Conference Paper |
Laser collision-induced fluorescence (LCIF) is a powerful diagnostic which can be used for making temporally and spatially resolved measurements of electron densities in a plasma discharge. The technique, which involves the measurement of optical emission emanating from higher energy excited states due to the redistribution of the lower energy laser-excited state by collisions with energetic elect...Show More
A microwave resonance diagnostic for measuring characteristics of pulsed ion beams
2014 IEEE International Power Modulator and High Voltage Conference (IPMHVC)
Year: 2014 | Conference Paper |
This paper describes an experiment to characterize ions generated by a pulsed vacuum arc by using a microwave resonant cavity (MRC) as a transient diagnostic. Specific information is desired on the various species which can drift into the beam during repetitive operations of arc plasma generation. The arc source reference voltage is elevated above ground (~200V), which results in a separation of i...Show More
Correlating metastable-atom density, reduced electric field, and electron energy distribution in a 1-torr argon discharge
J.B. Franek;S.H. Nogami;M.E. Koepke;V.I. Demidov;E.V. Barnat
Direct measurement of the intensities of the Ar 420.1nm and 419.8nm spectral lines, independent measurement of meta-stable-atom density, electron density, and electron temperature, inferred measurement of reduced electric field, and assumptions of the shape of the electron energy distribution in a 1-torr argon discharge are correlated within the extended-corona-model framework applied to the late ...Show More
Characterization of dynamic and structured plasma using laser-collision induced fluorescence
E.V. Barnat;B. R. Weatherford;V. I Kolobov;A. A. Hubble;J. E. Foster
Laser collision-induced fluorescence (LCIF)1 is a powerful diagnostic which can be used for making temporally and spatially resolved measurements of electron densities in a plasma discharge. The technique, which involves the measurement of optical emission emanating from higher energy excited states due to the redistribution of the lower energy laser-excited state by collisions with energetic elec...Show More
Measurement of the sheath surrounding a planar electron emitting surface in the afterglow of an RF plasma
2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)
Year: 2013 | Conference Paper |
Summary form only given. The potential of a sheath surrounding a planar, electron emitting cathode was measured in the afterglow of a capacitively coupled RF plasma. Using Langmuir and emissive probes, the electron temperature and plasma potential were measured as a function of time. The inflection point in the limit of zero emission, a highly accurate emissive probe technique to measure the plasm...Show More
Electron energetics in a helium pulsed nanosecond discharge
Benjamin T. Yee;John E. Foster;Brandon R. Weatherford;Edward V. Barnat
2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)
Year: 2013 | Conference Paper |
Summary form only given. Pulsed, nanosecond discharges (PNDs) are notable for their large volumes and nonthermal nature. The large volume is attractive for material processing and the nonthermal electron can be used to drive reactions with minimal gas or substrate heating. However, the stochasticity of such plasmas presents a challenge for simulations, while the short time scales and large fields ...Show More
3D vacuum ARC breakdown simulation: Many challenges and some solutions
Matthew M. Hopkins;Jeremiah J. Boerner;Edward V. Barnat;Paul S. Crozier;Matthew T. Bettencourt;Lawrence C. Musson;Harold E. Meyer;Russell Hooper;Christopher H. Moore
2012 Abstracts IEEE International Conference on Plasma Science
Year: 2012 | Conference Paper |
We present our current capabilities and plans targeting the simulation of 3D vacuum arc discharge in realistic geometries. Vacuum arc discharge is an incredibly challenging problem due to the enormous dynamic changes in plasma growth, collisional processes, and time scales. Our simulation model targets a co-planar Cu-Cu vacuum breakdown experiment. We will estimate the computational requirements f...Show More
Two-dimensional laser collision-induced fluorescence mapping of electron density and temperature near plasma cathode apertures
2011 Abstracts IEEE International Conference on Plasma Science
Year: 2011 | Conference Paper |
Summary form only given, as follows. Laser collision-induced fluorescence (LCIF) diagnostics are used to generate two-dimensional images of electron density and temperature inside a RF helium plasma cathode setup, near the electron extraction aperture. During electron current extraction, a region of dense plasma is seen at the aperture, and this aperture plasma is often surrounded by a layer of hi...Show More
Two-Dimensional LCIF Images of Electron Density and Temperature Within an ECR Plasma Cathode
Two-dimensional mappings of electron density and temperature within an electron cyclotron resonance (ECR) plasma cathode are presented. As electron current is extracted, a secondary plasma is formed on the upstream side of the extraction aperture, and the spatial distribution of the ECR plasma is affected. The aperture plasma is surrounded by a region of “hot” electrons, suggesting the possibility...Show More
Impact of Plasma Seeding on the Propagation of Ionization Waves Launched by Fast Voltage Pulses
The impact of the pulse repetition rate of nanosecond-scale voltage pulses on the generation of a plasma discharge in a glass tube is examined. Space-time images of the plasma-induced emission are used to quantify the velocity of the ionizing wave as the plasma propagates across the tube for various pulsed voltage repetition rates.Show More
Two-dimensional mapping of electron densities and temperatures using laser-collision induced flourescence
2010 Abstracts IEEE International Conference on Plasma Science
Year: 2010 | Conference Paper |
Summary form only given. We discuss the application of the laser-collision induced fluorescence technique to produce two-dimensional maps of both electron densities and electron temperatures in a helium plasma. A collisional-radiative model is used to describe the evolution of electronic states after laser excitation. We discuss generalizations to the time dependant results that are used to simpli...Show More
Structure in RF Hydrogen Plasma Induced by Magnetic Field
Images of the spatial structure of a capacitively coupled hydrogen discharge are presented for various strengths of applied magnetic field. With increasing magnetic field, we find that not only does the distribution of emission change because of the confinement of the electrons by the magnetic field, but we also find "dark-bands" regions that form in the discharge. By using narrowband interference...Show More
Time History and Spectra of the Light Emitted by Multimegavolt Water Switches
Joseph R. Woodworth;Edward Barnat;Ben Aragon;John Corley;Keith Hodge;James Blickem;Victor Anaya;Douglas Guthrie;David Bliss;Jane Lehr;John E. Maenchen;Peter Wakeland;Scott Drennan;David L. Johnson
We study the physics of water switching at 4 to 5 MV as part of Sandia's Z-Refurbishment program. We present time histories of the light emitted by two sets of water switches and correlate the light emission to the accelerator power pulse. Framing camera images demonstrate how the initial “bushy” streamers collapse to narrow current channels at late time. Spectroscopy of the water switches indicat...Show More
Electric field distribution around a biased probe immersed in an electrical discharge
The 33rd IEEE International Conference on Plasma Science, 2006. ICOPS 2006. IEEE Conference Record - Abstracts.
Year: 2006 | Conference Paper |
Summary form only given. Electric field distributions are measured around a biased probe immersed in an argon discharge. The distributions are measured as functions of probe bias, argon pressure, and distance of the probe from the "boundary" placed on the plasma by a powered electrode. The electric fields are symmetrically distributed around the probe when the probe is placed sufficiently far from...Show More
Spatially and Temporally Resolved Electric Fields in a Plasma Sheath
IEEE Conference Record - Abstracts. 2005 IEEE International Conference on Plasma Science
Year: 2005 | Conference Paper |
Summary form only given. We employ laser-induced dip-fluorescence to detect Stark shifts in atomic argon Rydberg states induced by electric fields present in the plasma sheath. The Stark shifts of these Rydberg states are calibrated for a set of known electric fields. The choice of probed Rydberg state determines the electric field range and resolution we can achieve. Both spatially and temporally...Show More
IEEE Account
Purchase Details
Profile Information
Need Help?
- US & Canada: +1 800 678 4333
- Worldwide: +1 732 981 0060
- Contact & Support
- About IEEE Xplore
- Contact Us
- Help
- Accessibility
- Terms of Use
- Nondiscrimination Policy
- Sitemap
- Privacy & Opting Out of Cookies
A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity.
© Copyright 2025 IEEE - All rights reserved. Use of this web site signifies your agreement to the terms and conditions.