This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc d...This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc discharge sources. Due to the absence of hotfilaments they exhibit an inherent simplicity both in mechanical and electrical aspects andconsequently offer advantages in terms of cost savings, gain in availability and reliability andreduced maintenance. This renders the RF plasma source attractive for any long pulse (> 10 sec) NBIsystem and in particular for the ITER NBI system. The latter, however, requires that the RF plasmasource is also capable of delivering negative rather than positive hydrogen ions. In the first partof the paper the types, characteristics and operation experience of RF plasma sources for positiveions in operation are described. The second part is devoted to the development for ITER NBI: thebasic requirements, physics and technology issues and the present status are discussed.展开更多
An increased of H ion beam current whenever argon gas is added has been observed. The physics behind argon effect is that in the production of more H atoms, a part of H atoms will be converted to H2*(v>4) to increa...An increased of H ion beam current whenever argon gas is added has been observed. The physics behind argon effect is that in the production of more H atoms, a part of H atoms will be converted to H2*(v>4) to increase H- density. Increase of nH depends on the rate of added Ar η %, primary filling pressure P, electron density neAr and recombination coefficient 7 of H atom. Adding 25% Ar is optimal, although there have been assumed various parameters. Increase of nH depends on decreased recombination coefficient 7, and increased primary filling pressure P. The increase of nH is small when the pressure P < 0.3 Pa. Optimized volume size L/R^2 is optimal for obtaining a maximum Ar effect.展开更多
文摘This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc discharge sources. Due to the absence of hotfilaments they exhibit an inherent simplicity both in mechanical and electrical aspects andconsequently offer advantages in terms of cost savings, gain in availability and reliability andreduced maintenance. This renders the RF plasma source attractive for any long pulse (> 10 sec) NBIsystem and in particular for the ITER NBI system. The latter, however, requires that the RF plasmasource is also capable of delivering negative rather than positive hydrogen ions. In the first partof the paper the types, characteristics and operation experience of RF plasma sources for positiveions in operation are described. The second part is devoted to the development for ITER NBI: thebasic requirements, physics and technology issues and the present status are discussed.
文摘An increased of H ion beam current whenever argon gas is added has been observed. The physics behind argon effect is that in the production of more H atoms, a part of H atoms will be converted to H2*(v>4) to increase H- density. Increase of nH depends on the rate of added Ar η %, primary filling pressure P, electron density neAr and recombination coefficient 7 of H atom. Adding 25% Ar is optimal, although there have been assumed various parameters. Increase of nH depends on decreased recombination coefficient 7, and increased primary filling pressure P. The increase of nH is small when the pressure P < 0.3 Pa. Optimized volume size L/R^2 is optimal for obtaining a maximum Ar effect.
