Theory of the electron sheath and presheath
Abstract
Here, electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the electron velocity distribution function (EVDF). This work provides a dedicated theory of electron sheaths, which suggests that they are not so simple. Motivated by EVDFs observed in particle-in-cell(PIC) simulations, a 1D model for the electron sheath and presheath is developed. In the model, under low temperature plasma conditions (Te >> Ti), an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient generates large flow velocities compared to what would be generated by ballistic motion in response to the electric field. It is found that in many situations, under common plasma conditions, the electron presheath extends much further into the plasma than an analogous ion presheath. PIC simulations reveal that the ion density in the electron presheath is determined by a flow around the electron sheath and that this flow ismore »
- Authors:
-
- Univ. of Iowa, Iowa City, IA (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Publication Date:
- Research Org.:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Org.:
- USDOE National Nuclear Security Administration (NNSA)
- OSTI Identifier:
- 1258479
- Alternate Identifier(s):
- OSTI ID: 1234112
- Report Number(s):
- SAND-2015-8558J
Journal ID: ISSN 1070-664X; PHPAEN; 642141
- Grant/Contract Number:
- AC04-94AL85000; AC04-94SL8500; AC05-06OR23100
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Physics of Plasmas
- Additional Journal Information:
- Journal Volume: 22; Journal Issue: 12; Journal ID: ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma sheaths; electrodes; plasma flows; Boltzmann equations; particle-in-cell method
Citation Formats
Scheiner, Brett, Baalrud, Scott D., Yee, Benjamin T., Hopkins, Matthew M., and Barnat, Edward V. Theory of the electron sheath and presheath. United States: N. p., 2015.
Web. doi:10.1063/1.4939024.
Scheiner, Brett, Baalrud, Scott D., Yee, Benjamin T., Hopkins, Matthew M., & Barnat, Edward V. Theory of the electron sheath and presheath. United States. https://doi.org/10.1063/1.4939024
Scheiner, Brett, Baalrud, Scott D., Yee, Benjamin T., Hopkins, Matthew M., and Barnat, Edward V. Wed .
"Theory of the electron sheath and presheath". United States. https://doi.org/10.1063/1.4939024. https://www.osti.gov/servlets/purl/1258479.
@article{osti_1258479,
title = {Theory of the electron sheath and presheath},
author = {Scheiner, Brett and Baalrud, Scott D. and Yee, Benjamin T. and Hopkins, Matthew M. and Barnat, Edward V.},
abstractNote = {Here, electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the electron velocity distribution function (EVDF). This work provides a dedicated theory of electron sheaths, which suggests that they are not so simple. Motivated by EVDFs observed in particle-in-cell(PIC) simulations, a 1D model for the electron sheath and presheath is developed. In the model, under low temperature plasma conditions (Te >> Ti), an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient generates large flow velocities compared to what would be generated by ballistic motion in response to the electric field. It is found that in many situations, under common plasma conditions, the electron presheath extends much further into the plasma than an analogous ion presheath. PIC simulations reveal that the ion density in the electron presheath is determined by a flow around the electron sheath and that this flow is due to 2D aspects of the sheath geometry. Simulations also indicate the presence of ion acoustic instabilities excited by the differential flow between electrons and ions in the presheath, which result in sheath edge fluctuations. The 1D model and time averaged PIC simulations are compared and it is shown that the model provides a good description of the electron sheath and presheath.},
doi = {10.1063/1.4939024},
journal = {Physics of Plasmas},
number = 12,
volume = 22,
place = {United States},
year = {Wed Dec 30 00:00:00 EST 2015},
month = {Wed Dec 30 00:00:00 EST 2015}
}
Web of Science
Works referenced in this record:
Sheaths in laboratory and space plasmas
journal, July 2013
- Robertson, Scott
- Plasma Physics and Controlled Fusion, Vol. 55, Issue 9
Global nonambipolar flow: Plasma confinement where all electrons are lost to one boundary and all positive ions to another boundary
journal, April 2007
- Baalrud, S. D.; Hershkowitz, N.; Longmier, B.
- Physics of Plasmas, Vol. 14, Issue 4
Response of the plasma to the size of an anode electrode biased near the plasma potential
journal, October 2014
- Barnat, E. V.; Laity, G. R.; Baalrud, S. D.
- Physics of Plasmas, Vol. 21, Issue 10
The Theory of Collectors in Gaseous Discharges
journal, October 1926
- Mott-Smith, H. M.; Langmuir, Irving
- Physical Review, Vol. 28, Issue 4
Theory of Electron Collection of Spherical Probes
journal, December 1961
- Medicus, G.
- Journal of Applied Physics, Vol. 32, Issue 12
Spherical Langmuir Probe in ``Drifting'' and ``Accelerated'' Maxwellian Distribution
journal, October 1962
- Medicus, G.
- Journal of Applied Physics, Vol. 33, Issue 10
Current collection by an active spherical electrode in an unmagnetized plasma
journal, December 1992
- Ahedo, E.; Martínez‐Sánchez, M.; Sanmartín, J. R.
- Physics of Fluids B: Plasma Physics, Vol. 4, Issue 12
On anode spots, double layers and plasma contactors
journal, October 1991
- Song, Bin; D'Angelo, N.; Merlino, R. L.
- Journal of Physics D: Applied Physics, Vol. 24, Issue 10
lonization-driven plasma dynamics in a high voltage sheath of a conducting body in the ionosphere
journal, August 1996
- Singh, Nagendra; Jaggernauth, Ashford
- Journal of Geophysical Research: Space Physics, Vol. 101, Issue A8
Enhancement of proton acceleration by frequency-chirped laser pulse in radiation pressure mechanism
journal, July 2015
- Vosoughian, H.; Riazi, Z.; Afarideh, H.
- Physics of Plasmas, Vol. 22, Issue 7
Probe-Induced Particle Circulation in a Plasma Crystal
journal, May 1998
- Law, D. A.; Steel, W. H.; Annaratone, B. M.
- Physical Review Letters, Vol. 80, Issue 19
Equilibrium states of anodic double layers
journal, April 2009
- Baalrud, S. D.; Longmier, B.; Hershkowitz, N.
- Plasma Sources Science and Technology, Vol. 18, Issue 3
Dynamics of fireballs
journal, May 2008
- Stenzel, R. L.; Ionita, C.; Schrittwieser, R.
- Plasma Sources Science and Technology, Vol. 17, Issue 3
Sheaths: More complicated than you think
journal, May 2005
- Hershkowitz, Noah
- Physics of Plasmas, Vol. 12, Issue 5
The Bohm criterion and sheath formation
journal, April 1991
- Riemann, K. -U
- Journal of Physics D: Applied Physics, Vol. 24, Issue 4
Time-varying impedance of the sheath on a probe in an RF plasma
journal, August 2006
- Chen, Francis F.
- Plasma Sources Science and Technology, Vol. 15, Issue 4
Experimental study and modeling of the electron-attracting sheath: The influence of secondary electron emission
journal, July 2008
- Schiesko, L.; Carrère, M.; Cartry, G.
- Physics of Plasmas, Vol. 15, Issue 7
Ion-acoustic noise excited by positive probes
journal, April 1981
- Glanz, J.; Hershkowitz, N.
- Plasma Physics, Vol. 23, Issue 4
Probe-Excited Oblique Ion-Acoustic Waves in a Multidipole Plasma Device
journal, March 1978
- D'angelo, N.; Herink, K.; Kozima, Hideo
- Journal of the Physical Society of Japan, Vol. 44, Issue 3
Kinetic theory of instability-enhanced collisional effects
journal, May 2010
- Baalrud, S. D.; Callen, J. D.; Hegna, C. C.
- Physics of Plasmas, Vol. 17, Issue 5
Kinetic theory of the presheath and the Bohm criterion
journal, March 2011
- Baalrud, S. D.; Hegna, C. C.
- Plasma Sources Science and Technology, Vol. 20, Issue 2
Extensions and applications of the Bohm criterion
journal, March 2015
- Baalrud, Scott D.; Scheiner, Brett; Yee, Benjamin
- Plasma Physics and Controlled Fusion, Vol. 57, Issue 4
Potential of a plasma bound between two biased walls
journal, August 2012
- Loizu, J.; Dominski, J.; Ricci, P.
- Physics of Plasmas, Vol. 19, Issue 8
Principles of Plasma Discharges and Materials Processing
book, January 2005
- Lieberman, Michael A.; Lichtenberg, Allan J.
On the LambertW function
journal, December 1996
- Corless, R. M.; Gonnet, G. H.; Hare, D. E. G.
- Advances in Computational Mathematics, Vol. 5, Issue 1
First Experimental Measurements of the Plasma Potential throughout the Presheath and Sheath at a Boundary in a Weakly Collisional Plasma
journal, September 2002
- Oksuz, L.; Hershkowitz, N.
- Physical Review Letters, Vol. 89, Issue 14
Plasma, presheath, collisional sheath and collisionless sheath potential profiles in weakly ionized, weakly collisional plasma
journal, February 2005
- Oksuz, L.; Hershkowitz, N.
- Plasma Sources Science and Technology, Vol. 14, Issue 1
Elastic and Inelastic Scattering of Low‐Velocity He + Ions in Helium
journal, May 1957
- Cramer, W. H.; Simons, J. H.
- The Journal of Chemical Physics, Vol. 26, Issue 5
Breakdown development in helium in high voltage open discharge with subnanosecond current front
journal, July 2015
- Schweigert, I. V.; Alexandrov, A. L.; Bokhan, P. A.
- Plasma Sources Science and Technology, Vol. 24, Issue 4
Why Perform Code-to-Code Comparisons: A Vacuum Arc Discharge Simulation Case Study
journal, May 2012
- Timko, H.; Crozier, P. S.; Hopkins, M. M.
- Contributions to Plasma Physics, Vol. 52, Issue 4
Instability-Enhanced Collisional Friction Can Determine the Bohm Criterion in Multiple-Ion-Species Plasmas
journal, November 2009
- Baalrud, S. D.; Hegna, C. C.; Callen, J. D.
- Physical Review Letters, Vol. 103, Issue 20
Langmuir's Paradox
journal, November 1955
- Gabor, D.; Ash, E. A.; Dracott, D.
- Nature, Vol. 176, Issue 4489
Kinetic Theory of Instability-Enhanced Collective Interactions in Plasma
text, January 2010
- Baalrud, Scott D.
- Zenodo
Works referencing / citing this record:
Electron sheath evolution controlled by a magnetic field in modified hollow cathode glow discharge
journal, September 2018
- Rane, R.; Chauhan, S.; Bharathi, P.
- Physics of Plasmas, Vol. 25, Issue 9
Two-fluid solutions for Langmuir probes in collisionless and isothermal plasma, over all space and bias potential
journal, September 2018
- Guittienne, Ph.; Howling, A. A.; Furno, I.
- Physics of Plasmas, Vol. 25, Issue 9
Particle simulation of a magnetized plasma sheath with the magnetic field parallel to the wall
journal, September 2018
- Li, Dehui; Wang, Shaojie
- Physics of Plasmas, Vol. 25, Issue 9
Investigation of multi-component magnetized plasma interaction with the carbon surface
journal, September 2019
- Basnet, Suresh; Khanal, Raju
- AIP Advances, Vol. 9, Issue 9
Sheath characteristics in a magnetically filtered low density low temperature multicomponent plasma with negative ions
journal, December 2019
- Borgohain, Binita; Bailung, H.
- Physics of Plasmas, Vol. 26, Issue 12
Influence of ion streaming instabilities on transport near plasma boundaries
journal, February 2016
- Baalrud, Scott D.
- Plasma Sources Science and Technology, Vol. 25, Issue 2
Radiation transport in kinetic simulations and the influence of photoemission on electron current in self-sustaining discharges
journal, January 2017
- Fierro, Andrew; Moore, Chris; Scheiner, Brett
- Journal of Physics D: Applied Physics, Vol. 50, Issue 6
Numerical simulation of the initial stage of unipolar arcing in fusion-relevant conditions
journal, July 2019
- Kaufmann, H. T. C.; Silva, C.; Benilov, M. S.
- Plasma Physics and Controlled Fusion, Vol. 61, Issue 9
Self-consistent modeling of self-organized patterns of spots on anodes of DC glow discharges
journal, May 2018
- Bieniek, M. S.; Almeida, P. G. C.; Benilov, M. S.
- Plasma Sources Science and Technology, Vol. 27, Issue 5
Bridging Child–Langmuir and Warren: exact and approximate solutions for the unipolar sheath of intermediate pressure
journal, January 2019
- Naggary, Schabnam; Engel, Dennis; Kroll, Laura
- Plasma Sources Science and Technology, Vol. 28, Issue 1
Influence of Ion Streaming Instabilities on Transport Near Plasma Boundaries
text, January 2015
- Baalrud, Scott D.
- arXiv
Electron sheath evolution controlled by a magnetic field in modified hollow cathode glow discharge
text, January 2018
- Rane, R.; Chauhan, S.; Bharathi, P.
- arXiv