Liquid-metal tokamak divertors

• Published in: Journal of nuclear materials Vol. 196-98; pp. 45 - 49
• Main Authors: Mirnov, S V, Dem'yanenko, V N, Murav'ev, E V
• Format: Journal Article
• Language: English
• Published: 01.01.1992
• ISSN: 0022-3115

Both limiters and divertor plates of the reactor scale tokamaks are known to be subjected to extremely high heat loads. The problem of quasistationary heat fluxes (approximately 10 super(7) W/m super(2)), removal, and even the more severe problem of plates protection against impulse heat release on the order of approximately 10 super(7) J/m super(2) during (0.1-1)x10 super(-3) s, are the most critical issues related to divertor regimes in tokamaks. Melting, cracking and other damages of plasma facing components may occur in these regimes. Thus a demand arose to provide the possibility to replace these critical components easily. The easiest possible solution is to replace the traditional contact refractory materials with liquid metals. The simplest realization of the idea was proposed already in the UWMAK project, where a rigid divertor plate was replaced by liquid lithium flow. However, some intrinsic properties of lithium impede its practical application: 1) burning under contact with water; 2) small difference between melting and boiling temperatures. Another candidate material, liquid Ga, is believed to be more adequate (T sub(m) = 30 degree C, T sub(b) = 2400 degree C). On the T-3M tokamak the first encouraging experiments were performed where a liquid Ga jet-drop curtain was tested as a tokamak limiter. The limiter is analogous to one which uses small refractory balls falling down through the plasma column edge. Experiments with a liquid Ga sheet limiter have also started. Experimental results and possible perspectives are discussed.