Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor

C. C. Klepper; J. T. Hogan; P. K. Mioduszewski; M. Ali Mahdavi; R. Maingi; L. W. Owen; M. J. Schaffer; D. Buchenauer; T. E. Evans; J. G. Gilligan; G. Haas; D. N. Hill; G. L. Jackson; T. W. Petrie

doi:10.1016/S0022-3115(06)80201-1

Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor

C. C. Klepper, J. T. Hogan, P. K. Mioduszewski, M. Ali Mahdavi, R. Maingi, L. W. Owen, M. J. Schaffer, D. Buchenauer, T. E. Evans, J. G. Gilligan, G. Haas, D. N. Hill, G. L. Jackson, T. W. Petrie

Diagnostics and Control

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Abstract

The DIII-D divertor baffle system was designed to facilitate density control in long pulse H-mode discharges by removing a particle flux equal to the neutral beam fueling rate (∼20 Torrl/s) with a ∼1 mTorr neutral pressure under the baffle (p₀). Initial measurements of the baffle pressure indicated that p₀∼10 mTorr (without pumping or biasing), a value much in excess of that required for long pulse density control. Radial sweeps of the X-point position have been employed to determine the maximum p₀, as well as to establish the dependence of this pressure on geometry. An estimate of the particle equilibration time for the baffle system has been made by studying the baffle pressure response to "giant" ELM effects. "Steady state" experiments in which the X-point position was fixed for ∼2.5 s have also been carried out and steady baffle pressures were observed. The scaling of baffle pressure with plasma parameters has been found to be similar under transient and "steady state" conditions. Detailed modeling of these experiments with the B2, DEGAS, and WDIFFUSE (wall model) codes has been performed.

Original language	English
Pages (from-to)	1090-1095
Number of pages	6
Journal	Journal of Nuclear Materials
Volume	196-198
Issue number	C
DOIs	https://doi.org/10.1016/S0022-3115(06)80201-1
State	Published - Dec 1 1992

Funding

The authors wish to thank Dr. R.D. Stambaugh for his support and encouragement in this work. The technical support from R. Ellis of LLNL and T. Rayburn of ORNL in the construction and installation of the fast ion gauge assembly under the baffle is also acknowledged. The valuable advice obtained from Dr. T. Carl-strom on the use of Thomson scattering and infrared interferometry data was greatly appreciated. This work was supported by the US Department of Energy under contract nos. DE-AC05-84OR21400 (Martin Marietta Energy Systems, Inc.) and DE-AC03-89ER51114 (General Atomics).

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US Department of Energy

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10.1016/S0022-3115(06)80201-1

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Klepper, C. C., Hogan, J. T., Mioduszewski, P. K., Ali Mahdavi, M., Maingi, R., Owen, L. W., Schaffer, M. J., Buchenauer, D., Evans, T. E., Gilligan, J. G., Haas, G., Hill, D. N., Jackson, G. L., & Petrie, T. W. (1992). Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor. Journal of Nuclear Materials, 196-198(C), 1090-1095. https://doi.org/10.1016/S0022-3115(06)80201-1

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title = "Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor",

abstract = "The DIII-D divertor baffle system was designed to facilitate density control in long pulse H-mode discharges by removing a particle flux equal to the neutral beam fueling rate (∼20 Torrl/s) with a ∼1 mTorr neutral pressure under the baffle (p0). Initial measurements of the baffle pressure indicated that p0∼10 mTorr (without pumping or biasing), a value much in excess of that required for long pulse density control. Radial sweeps of the X-point position have been employed to determine the maximum p0, as well as to establish the dependence of this pressure on geometry. An estimate of the particle equilibration time for the baffle system has been made by studying the baffle pressure response to {"}giant{"} ELM effects. {"}Steady state{"} experiments in which the X-point position was fixed for ∼2.5 s have also been carried out and steady baffle pressures were observed. The scaling of baffle pressure with plasma parameters has been found to be similar under transient and {"}steady state{"} conditions. Detailed modeling of these experiments with the B2, DEGAS, and WDIFFUSE (wall model) codes has been performed.",

author = "Klepper, {C. C.} and Hogan, {J. T.} and Mioduszewski, {P. K.} and {Ali Mahdavi}, M. and R. Maingi and Owen, {L. W.} and Schaffer, {M. J.} and D. Buchenauer and Evans, {T. E.} and Gilligan, {J. G.} and G. Haas and Hill, {D. N.} and Jackson, {G. L.} and Petrie, {T. W.}",

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doi = "10.1016/S0022-3115(06)80201-1",

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Klepper, CC, Hogan, JT, Mioduszewski, PK, Ali Mahdavi, M, Maingi, R, Owen, LW, Schaffer, MJ, Buchenauer, D, Evans, TE, Gilligan, JG, Haas, G, Hill, DN, Jackson, GL & Petrie, TW 1992, 'Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor', Journal of Nuclear Materials, vol. 196-198, no. C, pp. 1090-1095. https://doi.org/10.1016/S0022-3115(06)80201-1

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T1 - Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor

AU - Klepper, C. C.

AU - Hogan, J. T.

AU - Mioduszewski, P. K.

AU - Ali Mahdavi, M.

AU - Maingi, R.

AU - Owen, L. W.

AU - Schaffer, M. J.

AU - Buchenauer, D.

AU - Evans, T. E.

AU - Gilligan, J. G.

AU - Haas, G.

AU - Hill, D. N.

AU - Jackson, G. L.

AU - Petrie, T. W.

PY - 1992/12/1

Y1 - 1992/12/1

N2 - The DIII-D divertor baffle system was designed to facilitate density control in long pulse H-mode discharges by removing a particle flux equal to the neutral beam fueling rate (∼20 Torrl/s) with a ∼1 mTorr neutral pressure under the baffle (p0). Initial measurements of the baffle pressure indicated that p0∼10 mTorr (without pumping or biasing), a value much in excess of that required for long pulse density control. Radial sweeps of the X-point position have been employed to determine the maximum p0, as well as to establish the dependence of this pressure on geometry. An estimate of the particle equilibration time for the baffle system has been made by studying the baffle pressure response to "giant" ELM effects. "Steady state" experiments in which the X-point position was fixed for ∼2.5 s have also been carried out and steady baffle pressures were observed. The scaling of baffle pressure with plasma parameters has been found to be similar under transient and "steady state" conditions. Detailed modeling of these experiments with the B2, DEGAS, and WDIFFUSE (wall model) codes has been performed.

AB - The DIII-D divertor baffle system was designed to facilitate density control in long pulse H-mode discharges by removing a particle flux equal to the neutral beam fueling rate (∼20 Torrl/s) with a ∼1 mTorr neutral pressure under the baffle (p0). Initial measurements of the baffle pressure indicated that p0∼10 mTorr (without pumping or biasing), a value much in excess of that required for long pulse density control. Radial sweeps of the X-point position have been employed to determine the maximum p0, as well as to establish the dependence of this pressure on geometry. An estimate of the particle equilibration time for the baffle system has been made by studying the baffle pressure response to "giant" ELM effects. "Steady state" experiments in which the X-point position was fixed for ∼2.5 s have also been carried out and steady baffle pressures were observed. The scaling of baffle pressure with plasma parameters has been found to be similar under transient and "steady state" conditions. Detailed modeling of these experiments with the B2, DEGAS, and WDIFFUSE (wall model) codes has been performed.

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JO - Journal of Nuclear Materials

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ER -

Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor

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