NSCL, East Lansing, Michigan, USA
MSU, East Lansing, Michigan, USA
LBNL, Berkeley, California, USA
Heavy ion facilities such as the National Superconducting Cyclotron Laboratory (NSCL) often use ECR Ion Sources (ECRIS) for the production of highly charged ions to increase the efficiency of accelerating structures. Axial bremsstrahlung emission was studied on the Superconducting Source for Ions (SuSI) at the NSCL for 18 GHz and 13 GHz operation with oxygen. The hot electron temperatures were estimated from the bremsstrahlung high energy tail and seem to depend only on magnetic minimum in the same way as was found on VENUS [1], even in the case where 18 GHz and 13 GHz frequencies were compared for similarly sized ECR zones. Additionally, the time independent x-ray power increased at a significantly larger rate when operating the source in known regions of instability such as where the magnetic minimum approaches the ECR zone [2]. The results are discussed in the context of electron losses due to magnetic confinement.
*J. Benitez, et Al., in Proc. ECRIS'16, paper MOCO04.
**O. Tarvainen, et Al., Plas. Sourc. Sci. Technol., vol. 23, pp. 025020, 2014.
MSU, East Lansing, Michigan, USA
FRIB, East Lansing, Michigan, USA
NSCL, East Lansing, Michigan, USA
Instabilities in magnetized plasmas, such as the cyclotron instabilities identified at JYFL*, can cause fast variations of the extracted ECRIS beams. In order to understand the effect of the radial component and longitudinal gradient of the magnetic field on plasma stability a series of measurements has taken place using the Superconducting Source for Ions (SuSI) at the National Superconducting Cyclotron Laboratory (NSCL). We present here the results from investigations into the instability characteristics of the beam current from SuSI at 18 GHz by varying longitudinal and radial magnetic field profiles, injected microwave power, and bias disk voltage. Our investigation shows multiple regions of beam variation within the magnetic field v.s. power phase space with multiple distinct modes of variance.
*O. Tarvainen, et al., Plasma Sources Sci. Technol. Vol. 23 (2014)