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Title: Determining the ion temperature and energy distribution in a lithium-plasma interaction test stand with a retarding field energy analyzer

Journal Article · · Review of Scientific Instruments
DOI:https://doi.org/10.1063/1.4995601· OSTI ID:1535334

The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) experiment at the University of Illinois is a gas-puff driven, theta-pinch plasma source that is used as a test stand for off-normal plasma events incident on materials in the edge and divertor regions of a tokamak. The ion temperatures and resulting energy distributions are crucial for understanding how well a TELS pulse can simulate an extreme event in a larger, magnetic confinement device. A retarding field energy analyzer (RFEA) has been constructed for use with such a transient plasma due to its inexpensive and robust nature. The innovation surrounding the use of a control analyzer in conjunction with an actively sampling analyzer is presented and the conditions of RFEA operation are discussed, with results presented demonstrating successful performance under extreme conditions. Such extreme conditions are defined by heat fluxes on the order of 0.8 GW m-2 and on time scales of nearly 200 μs. Measurements from the RFEA indicate two primary features for a typical TELS discharge, following closely with the pre-ionizing coaxial gun discharge characteristics. For the case using the pre-ionization pulse (PiP) and the theta pinch, the measured ion signal showed an ion temperature of 23.3 ± 6.6 eV for the first peak and 17.6 ± 1.9 eV for the second peak. For the case using only the PiP, the measured signal showed an ion temperature of 7.9 ± 1.1 eV for the first peak and 6.6 ± 0.8 eV for the second peak. These differences illustrate the effectiveness of the theta pinch for imparting energy on the ions. This information also highlights the importance of TELS as being one of the few linear pulsed plasma sources whereby moderately energetic ions will strike targets without the need for sample biasing.

Research Organization:
Univ. of Illinois at Urbana-Champaign, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
Grant/Contract Number:
FG02-99ER54515; DEFG02-99ER54515
OSTI ID:
1535334
Alternate ID(s):
OSTI ID: 1373446
Journal Information:
Review of Scientific Instruments, Vol. 88, Issue 8; ISSN 0034-6748
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 (18)

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Surface damage and structure evolution of recrystallized tungsten exposed to ELM-like transient loads journal February 2016
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Deuterium retention in liquid lithium journal October 2002
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Scanning retarding field analyzer for plasma profile measurements in the boundary of the Alcator C-Mod tokamak journal March 2013
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Development of a high energy pulsed plasma simulator for the study of liquid lithium trenches journal December 2014
Laboratory Investigation of Vapor Shielding for Lithium-Coated Molybdenum in Devex journal March 2012
Space-charge limits of ion sensitive probes journal October 2013
Retarding field energy analyzer for the JET plasma boundary journal November 2003
Ion energy measurements in the scrape-off layer of MAST using a Retarding Field Analyzer journal August 2011

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