title: The effect of rf pulse pattern on bremsstrahlung and ion current time evolution of an ECRIS.
abstract: 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.
authors.affiliation: Department of Physics, University of Jyvaskyla, Jyvaskyla FI-40014, Finland. tommi.ropponen@jyu.fi
authors.forename: T
authors.initials: T
authors.lastname: Ropponen
authors.forename: O
authors.initials: O
authors.lastname: Tarvainen
authors.forename: V
authors.initials: V
authors.lastname: Toivanen
authors.forename: P
authors.initials: P
authors.lastname: Peura
authors.forename: P
authors.initials: P
authors.lastname: Jones
authors.forename: T
authors.initials: T
authors.lastname: Kalvas
authors.forename: H
authors.initials: H
authors.lastname: Koivisto
authors.forename: J
authors.initials: J
authors.lastname: Noland
authors.forename: D
authors.initials: D
authors.lastname: Leitner