Nuclear fusion : Ash disposal
In order for a fusion plasma not merely to ignite but to reach stationary combustion, it is well-known that the energy containment time t(E) must be sufficient to compensate for the heat balance of the plasma. But the time t(*)(alpha) during which alpha particles produced in fusion remain in the plasma must not be so long as to cause addition of intolerable amounts of helium ash to the fuel mixture. Thus alongside the established prerequisite for ignition, there is a further condition: t(*)(alpha)/t(E) less than 10. This useful quality criterion does not admit operating modes in which the transport processes within the plasma cause particles to be too well contained. Moreover, the exhaust systems, such as pump limiters or divertors, must be efficient enough to limit the return flow, from the wall into the combustion zone, of helium that has not been pumped away.
Bibliographic Reference: Article: Physikalische Blätter, Vol. 47 (1991) No. 3, pp. 217-219
Record Number: 199110613 / Last updated on: 1994-12-02
Original language: de
Available languages: de