THE JET MULTI-PELLET INJECTOR AND ITS FUTURE UPGRADES
The present multi-pellet injector operating on JET is equipped with three repetitive pneumatic guns for three different pellet sizes, capable of pellet speeds up to 1.5 km/s. It has now been operated satisfactorily for more than one year within its specification. The best plasma performance in its application has so far been achieved with pellet deposition near the magnetic axis, now only possible with relatively cold plasmas. For a given plasma, the pellet speed is the only free parameter with regard to the penetration depth, since the pellet size determines the number of particles delivered to the plasma. In order to enable central deposition at higher plasma temperatures, JET plans to employ an advanced gun system following the principles of hot pneumatics by adiabatic compression in two-stage guns capable of launching initially single, and in a later version multiple, pellets with velocities towards the 5 to 10 km/s range. The present injector is described, concentrating on the launcher-machine interface and its upgrading, the development programme directed to make a single-pellet high-speed launcher possible and the planning of the implementation of this prototype launcher. The preparations for a future multi-pellet launcher system are outlined.
Bibliographic Reference: REPORT: JET-P(89)16 (1989) AVAILABLE FROM THE PUBLICATIONS OFFICER, JET JOINT UNDERTAKING, ABINGDON, OXON. OX14 3EA (GB)
Record Number: 1989128017600 / Last updated on: 1990-11-09
Available languages: en