Sufficient stability condition for alpha-driven velocity-space modes in compression tokamak

Magnetic compression heating may invert the velocity distribution of alpha particles, which leads to velocity-space instabilities. A sufficient stability condition is derived for these modes in compression tokamaks. High-field high-density compression scenario like Zephyr satisfies this stability condition, while medium-field high-temperature compression scheme like TFTR has some possibilities of exciting velocity-space thermonuclear instabilities. (author)