H-mode access in the low density regime on JET

Y. Andrew, R. Sartori, E. Righi, E. De la Luna, S. Hacquin, D.F. Howell, N.C. Hawkes, L.D. Horton, A. Huber, A. Korotkov, M.G. O'Mullane, JET EFDA Contributors

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

1 H-mode access studies under conditions of very low plasma density provide valuable information on the, physics of the edge transport barrier formation and are an important part of the operational scenario development for the next step fusion device, ITER. JET operation with a very low edge electron density, (n) over bar (e) = 0.8-1.4 x 10(19) m(-3), with the MkII gas box septum divertor was found to have a significant effect on the power threshold for the L-H transition, P-th. A sharp `turning point' below which P-th increases with decreasing (n) over bar (e) is found for I-p/B-t values of 2.5 MA/2.7 T, 2.5 MA/2.6T 2.5 MA/2.4T and 2.2 MA/2.4T. The pedestal electron temperature demonstrates a very similar dependence on the edge (n) over tilde (e) as P-th. The role of Z(eff) in the variation of the H-mode power threshold with density is also considered. Shots with the divertor septum present are compared with an identical (n) over bar (e) scan, run with the MkII GB septum replacement plate divertor at 2.5 MA/2.7 T and 2.5 MA/2.6 T. The results from this investigation indicate that removal of the septum may have lowered the (n) over tilde (e) `turning point' for P-th.
LanguageEnglish
Pages479-488
Number of pages10
JournalPlasma Physics and Controlled Fusion
Volume48
Issue number4
DOIs
Publication statusPublished - 1 Apr 2006

Fingerprint

septum
Plasma density
Electron temperature
Carrier concentration
thresholds
Fusion reactions
Physics
plasma density
shot
boxes
fusion
electron energy
Gases
physics
gases

Keywords

  • spherical tokamaks
  • boundary layer effects
  • plasma-material interactions
  • plasma devices

Cite this

Andrew, Y., Sartori, R., Righi, E., De la Luna, E., Hacquin, S., Howell, D. F., ... Contributors, JET. EFDA. (2006). H-mode access in the low density regime on JET. Plasma Physics and Controlled Fusion, 48(4), 479-488. https://doi.org/10.1088/0741-3335/48/4/001
Andrew, Y. ; Sartori, R. ; Righi, E. ; De la Luna, E. ; Hacquin, S. ; Howell, D.F. ; Hawkes, N.C. ; Horton, L.D. ; Huber, A. ; Korotkov, A. ; O'Mullane, M.G. ; Contributors, JET EFDA. / H-mode access in the low density regime on JET. In: Plasma Physics and Controlled Fusion. 2006 ; Vol. 48, No. 4. pp. 479-488.
@article{a3b3e57181fe47b78410e795baba4ea6,
title = "H-mode access in the low density regime on JET",
abstract = "1 H-mode access studies under conditions of very low plasma density provide valuable information on the, physics of the edge transport barrier formation and are an important part of the operational scenario development for the next step fusion device, ITER. JET operation with a very low edge electron density, (n) over bar (e) = 0.8-1.4 x 10(19) m(-3), with the MkII gas box septum divertor was found to have a significant effect on the power threshold for the L-H transition, P-th. A sharp `turning point' below which P-th increases with decreasing (n) over bar (e) is found for I-p/B-t values of 2.5 MA/2.7 T, 2.5 MA/2.6T 2.5 MA/2.4T and 2.2 MA/2.4T. The pedestal electron temperature demonstrates a very similar dependence on the edge (n) over tilde (e) as P-th. The role of Z(eff) in the variation of the H-mode power threshold with density is also considered. Shots with the divertor septum present are compared with an identical (n) over bar (e) scan, run with the MkII GB septum replacement plate divertor at 2.5 MA/2.7 T and 2.5 MA/2.6 T. The results from this investigation indicate that removal of the septum may have lowered the (n) over tilde (e) `turning point' for P-th.",
keywords = "spherical tokamaks, boundary layer effects , plasma-material interactions, plasma devices",
author = "Y. Andrew and R. Sartori and E. Righi and {De la Luna}, E. and S. Hacquin and D.F. Howell and N.C. Hawkes and L.D. Horton and A. Huber and A. Korotkov and M.G. O'Mullane and Contributors, {JET EFDA}",
year = "2006",
month = "4",
day = "1",
doi = "10.1088/0741-3335/48/4/001",
language = "English",
volume = "48",
pages = "479--488",
journal = "Plasma Physics and Controlled Fusion",
issn = "0741-3335",
number = "4",

}

Andrew, Y, Sartori, R, Righi, E, De la Luna, E, Hacquin, S, Howell, DF, Hawkes, NC, Horton, LD, Huber, A, Korotkov, A, O'Mullane, MG & Contributors, JETEFDA 2006, 'H-mode access in the low density regime on JET' Plasma Physics and Controlled Fusion, vol. 48, no. 4, pp. 479-488. https://doi.org/10.1088/0741-3335/48/4/001

H-mode access in the low density regime on JET. / Andrew, Y.; Sartori, R.; Righi, E.; De la Luna, E.; Hacquin, S.; Howell, D.F.; Hawkes, N.C.; Horton, L.D.; Huber, A.; Korotkov, A.; O'Mullane, M.G.; Contributors, JET EFDA.

In: Plasma Physics and Controlled Fusion, Vol. 48, No. 4, 01.04.2006, p. 479-488.

Research output: Contribution to journalArticle

TY - JOUR

T1 - H-mode access in the low density regime on JET

AU - Andrew, Y.

AU - Sartori, R.

AU - Righi, E.

AU - De la Luna, E.

AU - Hacquin, S.

AU - Howell, D.F.

AU - Hawkes, N.C.

AU - Horton, L.D.

AU - Huber, A.

AU - Korotkov, A.

AU - O'Mullane, M.G.

AU - Contributors, JET EFDA

PY - 2006/4/1

Y1 - 2006/4/1

N2 - 1 H-mode access studies under conditions of very low plasma density provide valuable information on the, physics of the edge transport barrier formation and are an important part of the operational scenario development for the next step fusion device, ITER. JET operation with a very low edge electron density, (n) over bar (e) = 0.8-1.4 x 10(19) m(-3), with the MkII gas box septum divertor was found to have a significant effect on the power threshold for the L-H transition, P-th. A sharp `turning point' below which P-th increases with decreasing (n) over bar (e) is found for I-p/B-t values of 2.5 MA/2.7 T, 2.5 MA/2.6T 2.5 MA/2.4T and 2.2 MA/2.4T. The pedestal electron temperature demonstrates a very similar dependence on the edge (n) over tilde (e) as P-th. The role of Z(eff) in the variation of the H-mode power threshold with density is also considered. Shots with the divertor septum present are compared with an identical (n) over bar (e) scan, run with the MkII GB septum replacement plate divertor at 2.5 MA/2.7 T and 2.5 MA/2.6 T. The results from this investigation indicate that removal of the septum may have lowered the (n) over tilde (e) `turning point' for P-th.

AB - 1 H-mode access studies under conditions of very low plasma density provide valuable information on the, physics of the edge transport barrier formation and are an important part of the operational scenario development for the next step fusion device, ITER. JET operation with a very low edge electron density, (n) over bar (e) = 0.8-1.4 x 10(19) m(-3), with the MkII gas box septum divertor was found to have a significant effect on the power threshold for the L-H transition, P-th. A sharp `turning point' below which P-th increases with decreasing (n) over bar (e) is found for I-p/B-t values of 2.5 MA/2.7 T, 2.5 MA/2.6T 2.5 MA/2.4T and 2.2 MA/2.4T. The pedestal electron temperature demonstrates a very similar dependence on the edge (n) over tilde (e) as P-th. The role of Z(eff) in the variation of the H-mode power threshold with density is also considered. Shots with the divertor septum present are compared with an identical (n) over bar (e) scan, run with the MkII GB septum replacement plate divertor at 2.5 MA/2.7 T and 2.5 MA/2.6 T. The results from this investigation indicate that removal of the septum may have lowered the (n) over tilde (e) `turning point' for P-th.

KW - spherical tokamaks

KW - boundary layer effects

KW - plasma-material interactions

KW - plasma devices

U2 - 10.1088/0741-3335/48/4/001

DO - 10.1088/0741-3335/48/4/001

M3 - Article

VL - 48

SP - 479

EP - 488

JO - Plasma Physics and Controlled Fusion

T2 - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

SN - 0741-3335

IS - 4

ER -

Andrew Y, Sartori R, Righi E, De la Luna E, Hacquin S, Howell DF et al. H-mode access in the low density regime on JET. Plasma Physics and Controlled Fusion. 2006 Apr 1;48(4):479-488. https://doi.org/10.1088/0741-3335/48/4/001