skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Control of hydrogen content and fuel recycling for long pulse high performance plasma operation in EAST

Abstract

Control of fuel recycling and hydrogen content in the Experimental Advanced Superconducting Tokamak (EAST) using various methods is studied for high-power long pulse high confinement mode (H-mode) plasma operation. The results show that long duration first wall baking and discharge cleaning in EAST provides the necessary clean vacuum environment with a high ultimate vacuum of 3.6 × 10-6 Pa and low outgassing rate of ~1.5 × 10-4 Pa m3 s-1 for plasma operation. In-vessel cryopumps are found to provide an efficient method for particle recycling control in the divertor region to decrease global recycling coefficient (R global) from ~1.0 to ~0.8 during ohmic heating plasmas, and it provides a high particle exhausting rate of 1020_1021 D-atoms s-1 in high-power plasma operations. Long duration silicon coating is found to be more powerful than baking and discharge cleaning, which reduces the H/(H + D) ratio gradually to a value as low as 8%, and lithium coating is more effective and more efficient than silicon coating, to further reduce the H/(H + D) ratio to 3%. Real-time lithium powder injection is a novel method for recycling control, which reduces R global from 0.94 to 0.82 under lithium coating wall conditioning. By the combinationmore » and optimization of the above methods, H-mode plasmas with low hydrogen content and low fuel recycling have been achieved in EAST and have been extended gradually to 101 s in 2017. Recycling flux has even decreased gradually during 101 s H-mode plasmas due to increased first wall temperature and the resulting increased Li-II emission. These results provide valuable references on hydrogen content and fuel recycling control for long pulse H-mode plasmas of up to 400–1000 s with high-power heating in EAST and future fusion devices.« less

Authors:
 [1];  [2];  [1]; ORCiD logo [3];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Chinese Academy of Sciences (CAS), Hefei (China). Inst. of Plasma Physics
  2. Chinese Academy of Sciences (CAS), Hefei (China). Inst. of Plasma Physics; Univ. of Science and Technology of China, Hefei (China)
  3. Chinese Academy of Sciences (CAS), Hefei (China). Inst. of Plasma Physics; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
the EAST Team
OSTI Identifier:
1619199
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 12; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; fuel recycling; long pulse operation; wall conditioning; hydrogen content; EAST

Citation Formats

Yu, Y. W., Hu, J. S., Zuo, G. Z., Sun, Z., Wang, L., Xu, W., Wang, J. R., Cao, B., Gao, W., Xu, J. C., and Li, J. G. Control of hydrogen content and fuel recycling for long pulse high performance plasma operation in EAST. United States: N. p., 2019. Web. https://doi.org/10.1088/1741-4326/ab3ead.
Yu, Y. W., Hu, J. S., Zuo, G. Z., Sun, Z., Wang, L., Xu, W., Wang, J. R., Cao, B., Gao, W., Xu, J. C., & Li, J. G. Control of hydrogen content and fuel recycling for long pulse high performance plasma operation in EAST. United States. https://doi.org/10.1088/1741-4326/ab3ead
Yu, Y. W., Hu, J. S., Zuo, G. Z., Sun, Z., Wang, L., Xu, W., Wang, J. R., Cao, B., Gao, W., Xu, J. C., and Li, J. G. Wed . "Control of hydrogen content and fuel recycling for long pulse high performance plasma operation in EAST". United States. https://doi.org/10.1088/1741-4326/ab3ead. https://www.osti.gov/servlets/purl/1619199.
@article{osti_1619199,
title = {Control of hydrogen content and fuel recycling for long pulse high performance plasma operation in EAST},
author = {Yu, Y. W. and Hu, J. S. and Zuo, G. Z. and Sun, Z. and Wang, L. and Xu, W. and Wang, J. R. and Cao, B. and Gao, W. and Xu, J. C. and Li, J. G.},
abstractNote = {Control of fuel recycling and hydrogen content in the Experimental Advanced Superconducting Tokamak (EAST) using various methods is studied for high-power long pulse high confinement mode (H-mode) plasma operation. The results show that long duration first wall baking and discharge cleaning in EAST provides the necessary clean vacuum environment with a high ultimate vacuum of 3.6 × 10-6 Pa and low outgassing rate of ~1.5 × 10-4 Pa m3 s-1 for plasma operation. In-vessel cryopumps are found to provide an efficient method for particle recycling control in the divertor region to decrease global recycling coefficient (R global) from ~1.0 to ~0.8 during ohmic heating plasmas, and it provides a high particle exhausting rate of 1020_1021 D-atoms s-1 in high-power plasma operations. Long duration silicon coating is found to be more powerful than baking and discharge cleaning, which reduces the H/(H + D) ratio gradually to a value as low as 8%, and lithium coating is more effective and more efficient than silicon coating, to further reduce the H/(H + D) ratio to 3%. Real-time lithium powder injection is a novel method for recycling control, which reduces R global from 0.94 to 0.82 under lithium coating wall conditioning. By the combination and optimization of the above methods, H-mode plasmas with low hydrogen content and low fuel recycling have been achieved in EAST and have been extended gradually to 101 s in 2017. Recycling flux has even decreased gradually during 101 s H-mode plasmas due to increased first wall temperature and the resulting increased Li-II emission. These results provide valuable references on hydrogen content and fuel recycling control for long pulse H-mode plasmas of up to 400–1000 s with high-power heating in EAST and future fusion devices.},
doi = {10.1088/1741-4326/ab3ead},
journal = {Nuclear Fusion},
number = 12,
volume = 59,
place = {United States},
year = {2019},
month = {10}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 2 works
Citation information provided by
Web of Science

Figures / Tables:

Fig. 1 Fig. 1: Wall conditioning procedure in EAST 2015-2016 campaign, (a) first wall temperature (red line) and accumulated GDC operation duration (blue line), (b) accumulated amount of removed H2 in gram, (c) partial pressures of H2 (black line with $\square$) and H2O (red line with 〇).

Save / Share:

Works referenced in this record:

Investigation of the origin of neutrals in the main chamber of Alcator C-Mod
journal, May 2002

  • Lipschultz, B.; LaBombard, B.; Pitcher, C. S.
  • Plasma Physics and Controlled Fusion, Vol. 44, Issue 6
  • DOI: 10.1088/0741-3335/44/6/309

Integration of high power, long pulse operation in Tore Supra in preparation for ITER
journal, September 2007


Dependence of the L–H transition on X-point geometry and divertor recycling on NSTX
journal, October 2013


Active Recycling Control Through Lithium Injection in EAST
journal, May 2018


New Steady-State Quiescent High-Confinement Plasma in an Experimental Advanced Superconducting Tokamak
journal, February 2015


Real time wall conditioning with lithium powder injection in long pulse H-mode plasmas in EAST with tungsten divertor
journal, May 2019


Low-recycling conditions and improved core confinement in steady-state operation scenarios in JET (Joint European Torus)
journal, March 2013


Global particle balance and wall recycling properties of long duration discharges on TRIAM-1M
journal, May 2004


Real-time reduction of tungsten impurity influx using lithium powder injection in EAST
journal, December 2018


Plasma wall interaction during long pulse operation in Tore Supra
journal, March 1999


Integrated Operating Scenario to Achieve 100-Second, High Electron Temperature Discharge on EAST
journal, April 2016


Particle exhaust and recycling control by active divertor pumping in EAST
journal, August 2011


Main chamber high recycling on ASDEX upgrade
journal, June 2009


Enhanced Energy Confinement and Performance in a Low-Recycling Tokamak
journal, August 2006


Impact of minority concentration on fundamental (H)D ICRF heating performance in JET-ILW
journal, April 2014


Isolation of the Improved Core Confinement from High Recycling and Radiative Boundary in Reversed Magnetic Shear Plasmas of JT-60U
journal, February 1997


A simple apparatus for the injection of lithium aerosol into the scrape-off layer of fusion research devices
journal, November 2010


Wall conditioning in fusion devices and its influence on plasma performance
journal, September 1996


The effect of divertor magnetic balance on H-mode performance in DIII-D
journal, March 2001


Role of recycling flux in gas fuelling in the Large Helical Device
journal, December 2003


An overview of lithium experiments on HT-7 and EAST during 2012
journal, December 2014


Plasma-material interactions in current tokamaks and their implications for next step fusion reactors
journal, December 2001


Influence of lithium coatings with large-area coverage on EAST plasma performance
journal, December 2014