The effect of rf pulse pattern on bremsstrahlung and ion current time evolution of an ECRIS.
Time-resolved helium ion production and bremsstrahlung emission from JYFL 14 GHz ECRIS is presented with different radio frequency pulse lengths. rf on times are varied from 5 to 50 ms and rf off times from 10 to 1000 ms between different measurement sets. It is observed that the plasma breakdown occurs a few milliseconds after launching the rf power into the plasma chamber, and in the beginning of the rf pulses a preglow transient is seen. During this transient the ion beam currents are increased by several factors compared to a steady state situation. By adjusting the rf pulse separation the maximum ion beam currents can be maintained during the so-called preglow regime while the amount of bremsstrahlung radiation is significantly decreased.
Ropponen
T
T
Department of Physics, University of Jyvaskyla, Jyvaskyla FI-40014, Finland. tommi.ropponen@jyu.fi
Tarvainen
O
O
Toivanen
V
V
Peura
P
P
Jones
P
P
Kalvas
T
T
Koivisto
H
H
Noland
J
J
Leitner
D
D