Search Menu
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information
Search Scholarly Publications

Title: Design and calibration of a retarding field energy analyzer for the LTX-β scrape off layer and modeling of electrostatic potential in a collisionless SOL

Abstract

The Lithium Tokamak eXperiment (LTX) is a spherical tokamak device designed to study lithium plasma facing components (PFCs). The lithium coated wall of LTX has been demonstrated to produce a plasma edge with high electron temperature (200 eV or greater). Plasma density in the outer scrape-off layer (SOL) is also found to be very low, around 2 × 1017m-3, as a result of the low recycling lithium boundary. The high temperature, low collisionality region of the plasma extends into the SOL. The recent upgrade to LTX-β includes installation of a neutral beam, which will provide further heating and fueling of the core plasma. Core and edge diagnostics will also be expanded. As part of this expansion, a Retarding Field Energy Analyzer (RFEA) has been developed for the SOL of LTX-β. Measurements of the ion temperature, ion energy distribution, and the local space potential will be performed in the SOL plasma using this RFEA. Upgraded high field side (HFS) and low field side (LFS) Langmuir probes will replace existing triple probes so that higher electron temperatures can be more reliably measured. The HFS probes are also positioned to give radial and vertical gradient measurements. The design of the RFEA will bemore » presented, along with calibration data.Since a high temperature, low collisional edge is expected for LTX-β, with a high mirror ratio near the LCFS (around 4), the majority of particles in the SOL will be mirror-trapped. Trapped particle effects will therefore become significant in the physics of the SOL plasma, and warrant further theoretical investigations. Here we present a theoretical study of the ambipolar potential formed in the collisionless SOL via differential loss of the electrons and ions, known as the Pastukhov potential in the literature. Numerical results will also be presented.« less

Authors:
ORCiD logo; ; ; ; ;
Publication Date:
Research Org.:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1529733
Alternate Identifier(s):
OSTI ID: 1648973
Grant/Contract Number:  
AC02-09CH11466; AC05-00OR22725; AC52-07NA27344
Resource Type:
Published Article
Journal Name:
Nuclear Materials and Energy
Additional Journal Information:
Journal Name: Nuclear Materials and Energy Journal Volume: 19 Journal Issue: C; Journal ID: ISSN 2352-1791
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Lithium PFC; scrape off layer; ambipolar potential; retarding field energy analyzer

Citation Formats

Zhang, X., Elliott, D. B., Maan, A., Boyle, D. P., Kaita, R., and Majeski, R. Design and calibration of a retarding field energy analyzer for the LTX-β scrape off layer and modeling of electrostatic potential in a collisionless SOL. Netherlands: N. p., 2019. Web. doi:10.1016/j.nme.2019.02.027.
Copy to clipboard
Zhang, X., Elliott, D. B., Maan, A., Boyle, D. P., Kaita, R., & Majeski, R. Design and calibration of a retarding field energy analyzer for the LTX-β scrape off layer and modeling of electrostatic potential in a collisionless SOL. Netherlands. https://doi.org/10.1016/j.nme.2019.02.027
Copy to clipboard
Zhang, X., Elliott, D. B., Maan, A., Boyle, D. P., Kaita, R., and Majeski, R. Wed . "Design and calibration of a retarding field energy analyzer for the LTX-β scrape off layer and modeling of electrostatic potential in a collisionless SOL". Netherlands. https://doi.org/10.1016/j.nme.2019.02.027.
Copy to clipboard
@article{osti_1529733,
title = {Design and calibration of a retarding field energy analyzer for the LTX-β scrape off layer and modeling of electrostatic potential in a collisionless SOL},
author = {Zhang, X. and Elliott, D. B. and Maan, A. and Boyle, D. P. and Kaita, R. and Majeski, R.},
abstractNote = {The Lithium Tokamak eXperiment (LTX) is a spherical tokamak device designed to study lithium plasma facing components (PFCs). The lithium coated wall of LTX has been demonstrated to produce a plasma edge with high electron temperature (200 eV or greater). Plasma density in the outer scrape-off layer (SOL) is also found to be very low, around 2 × 1017m-3, as a result of the low recycling lithium boundary. The high temperature, low collisionality region of the plasma extends into the SOL. The recent upgrade to LTX-β includes installation of a neutral beam, which will provide further heating and fueling of the core plasma. Core and edge diagnostics will also be expanded. As part of this expansion, a Retarding Field Energy Analyzer (RFEA) has been developed for the SOL of LTX-β. Measurements of the ion temperature, ion energy distribution, and the local space potential will be performed in the SOL plasma using this RFEA. Upgraded high field side (HFS) and low field side (LFS) Langmuir probes will replace existing triple probes so that higher electron temperatures can be more reliably measured. The HFS probes are also positioned to give radial and vertical gradient measurements. The design of the RFEA will be presented, along with calibration data.Since a high temperature, low collisional edge is expected for LTX-β, with a high mirror ratio near the LCFS (around 4), the majority of particles in the SOL will be mirror-trapped. Trapped particle effects will therefore become significant in the physics of the SOL plasma, and warrant further theoretical investigations. Here we present a theoretical study of the ambipolar potential formed in the collisionless SOL via differential loss of the electrons and ions, known as the Pastukhov potential in the literature. Numerical results will also be presented.},
doi = {10.1016/j.nme.2019.02.027},
journal = {Nuclear Materials and Energy},
number = C,
volume = 19,
place = {Netherlands},
year = {Wed May 01 00:00:00 EDT 2019},
month = {Wed May 01 00:00:00 EDT 2019}
}
Copy to clipboard
Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
https://doi.org/10.1016/j.nme.2019.02.027
Copyright Statement
Other availability
Search WorldCat Search WorldCat to find libraries that may hold this journal
Citation Metrics:
Cited by: 2 works
Citation information provided by
Web of Science
Save / Share:
Export Metadata
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.

Works referenced in this record:

Compatibility of lithium plasma-facing surfaces with high edge temperatures in the Lithium Tokamak Experiment
journal, May 2017

  • Majeski, R.; Bell, R. E.; Boyle, D. P.
  • Physics of Plasmas, Vol. 24, Issue 5
  • DOI: 10.1063/1.4977916

Ignited spherical tokamaks and plasma regimes with LiWalls
journal, November 2004

End-loss processes from mirror machines
journal, April 1977

Effects of Space Charges in Gridded Energy Analyzer
journal, December 1993

  • Honzawa, Tadao; Sekizawa, Toshimitsu; Miyauchi, Yasunori
  • Japanese Journal of Applied Physics, Vol. 32, Issue Part 1, No. 12A
  • DOI: 10.1143/JJAP.32.5748

On lithium walls and the performance of magnetic fusion devices
journal, May 2003

  • Krasheninnikov, S. I.; Zakharov, L. E.; Pereverzev, G. V.
  • Physics of Plasmas, Vol. 10, Issue 5
  • DOI: 10.1063/1.1558293

Collisional loss of electrostatically confined species in a magnetic mirror
journal, September 1978

Observation of Flat Electron Temperature Profiles in the Lithium Tokamak Experiment
journal, July 2017

Scanning retarding field analyzer for plasma profile measurements in the boundary of the Alcator C-Mod tokamak
journal, March 2013

  • Brunner, D.; LaBombard, B.; Ochoukov, R.
  • Review of Scientific Instruments, Vol. 84, Issue 3
  • DOI: 10.1063/1.4793785

Collisional losses of electrons from an adiabatic trap in a plasma with a positive potential
journal, January 1974

Space-charge limits of ion sensitive probes
journal, October 2013

Ion losses from end-stoppered mirror trap
journal, January 1978

Equilibrium reconstruction with 3D eddy currents in the Lithium Tokamak eXperiment
journal, April 2017

  • Hansen, C.; Boyle, D. P.; Schmitt, J. C.
  • Physics of Plasmas, Vol. 24, Issue 4
  • DOI: 10.1063/1.4981214
    Sort by:
    [ × clear filter / sort ]

    Similar Records in DOE PAGES and OSTI.GOV collections: