ECRIS 2010
A CORRECTION SCHEME FOR THE HEXAPOLAR ERROR OF AN ION BEAM EXTRACTED FROM AN ECRIS
The extraction of any ion beam from ECRIS is determined by the good confinement of such ion sources. It has been shown earlier, that the ions are coming from these places, where the confinement is weakest. The assumption that the low energy ions are strongly bound to the magnetic field lines require furthermore, that only these ions starting on a magnetic field line going hrough the extraction aperture can be extracted. Depending on the setting of the magnetic field, these field lines may come from the loss lines at plasma hamber radius. Because the longitudinal position of these field lines depends on the azimuthal position at the extraction electrode, the ions are extracted from different magnetic flux densities. Whereas the solenoidal component can only be transferred into another phase space projection, the hexapolar component can be compensated by an additional hexapole after the first beam line cusing solenoid. The hexapole has to be rotatable in azimuthal direction and oveable in longitudinal direction. For a good correction the beam needs to have such a radial phase space distribution, that the force given by this hexapole acts on the aberrated beam exactly in such a way that it create a linear distribution after that corrector. more...
Author: P. Spädtke et al.
MICROWAVE FREQUENCY DEPENDENCE OF THE PROPERTIES OF THE ION BEAM EXTRACTED FROM A CAPRICE TYPE ECRIS
In order to improve the quality of ion beams extracted from ECR ion sources it is mandatory to better understand the relations between the plasma conditions and the beam properties. The present investigations concentrate on the analysis of different beam properties under the influence of various applications of frequency tuning and of multiple frequency heating. The changes in the microwave frequency feeding the plasma affect the electromagnetic field distribution and the dimension and position of the ECR surface inside the plasma chamber. This in turn has an influence on the generation of the extracted ion beam in terms of intensity, shape and emittance. In order to analyze the corresponding effects, measurements have been performed with the CAPRICE-Type ECRIS installed at the ECR Injector Setup (EIS) of GSI. The experimental setup uses a microwave sweep generator which feed a TWTA (Traveling Wave Tube Amplifier) covering a wide frequency range from 12.5 to 16.5 GHz. This arrangement provides a precise determination of the frequencies and of the reflection coefficient along with the beam properties. A sequence of viewing targets positioned inside the beam line monitors the beam shape evolution. more...
Author: F. Maimone et al.