Presentation Impact of additional plasma heating on detached plasma formation in divertor simulation experiments using the GAMMA 10/PDX tandem mirror

Nakashima, Y.  ,  Islam, M.S.  ,  Iijima, T.  ,  Yokodo, T.  ,  Sakamoto, M.  ,  Ezumi, N.  ,  Yoshikawa, M.  ,  Asakura, Nobuyuki  ,  Fukumoto, Masakatsu  ,  Hatayama, A.  ,  Hirata, M.  ,  Ichimura, K.  ,  Ichimur, M.  ,  Ikezoe, R.  ,  Imai, T.  ,  Islam, M.M.  ,  Kariya, T.  ,  Katanuma, I.  ,  Kohagura, J.  ,  Lee, G.  ,  Masuzaki, S.  ,  Minami, R.  ,  Nakano, Tomohide  ,  Nojiri, K.  ,  Numakura, T.  ,  Sawada, K.  ,  Terakado, A.  ,  Togo, S.  ,  Yamashita, S.  ,  Yoshimoto, T.

In this paper, the detailed results of the effect of additional plasmaheating under the condition of plasma detachment produced in thelarge tandem mirror GAMMA 10/PDX. In this experiment, the ECHpulse of 150 kW was applied to the upstream region of detachedplasmas established by injecting heavy noble gases (Ar, Kr and Xe) andthe significant phenomena on detached to attached transition weremeasured with Langmuir probes, calorimeters, spectrometers and ahigh-speed camera. In the presentation, detailed behavior of theplasma parameters is described and the effect of ECH is discussed interms of radiation loss power and ionization and recombinationprocesses.During the plasma detachment experiments by impurity gas seeding, a short pulse (25 ms) of ECH was applied at the east plug/barriercell to examine the effects of ECH on the detached plasma. A brief summary of the outcomes is given below: ECH heating pulse significantly increases the heat flux at the west end-cell, which indicates detached to attached transition phenomena. During ECH injection period, the ion flux also increases with the increasing gas injection. The emission from the impurity ion enhances significantly during ECH injection period. The emission intensity captured with fast camera also shows a clear dependence on the gas throughput of N2 gas. Comparison of the results using light impurities (N2 and Ne) to those by a heavy impurity gas (Ar) indicates that detached plasma with N2 seeding has a certain tolerance for the additional heating. These outcomes also indicate to consider the sustainability of the detached plasma during ELM.
The 23rd International Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI-23)

Number of accesses :  

Other information