Abstract
ELMy H-modes in helium-4 plasmas provide valuable information on ELMy H-mode physics as well as a possible early low activation operational phase for next-step tokamaks, such as ITER. With this in mind, a series of helium-4 H-mode experiments were performed on JET with pure helium-4 NET auxiliary heating (up to 12 MW). A set of ELMy H-mode plasmas were produced, in both the Type I ELM regime and a second regime, which showed characteristics similar to the deuterium Type III regime, but with a reverse ELM frequency dependence on power. Sawteeth were also observed, and had similar behaviour to those seen in deuterium. Compared with deuterium plasmas, Type I ELMy H-mode confinement is seen to be 28 ± 6% poorer in helium-4 plasmas and the L-H power threshold 42 ± 10% larger. This is the opposite of the behaviour predicted by experimental isotope mass scalings from hydrogenic plasmas.
Original language | English |
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Pages (from-to) | 519-534 |
Number of pages | 16 |
Journal | Plasma Physics and Controlled Fusion |
Volume | 46 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2004 |
Externally published | Yes |