22 Set 2009 EPPC 09 CERN September /14 Solid-State MARX Type Circuit for the ISOLDE Target Voltage Modulator L.M. Redondo*, J. Fernando Silva #, H. Canacsinh*, N. Ferro*, C. Mendes*, R. Soares , J. Schipper and A. Fowler Work supported by FCT project CERN-FP * Nuclear Physics Center - Lisbon University (CFNUL), Lisbon, Portugal # Center for Innovation in Electrical and Energy Engineering TU Lisbon, Lisbon, Portugal ABT Group, TE Department, CERN, Switzerland 22 Set 2009 EPPC 09 CERN September /14 Summary ISOLDE Target Voltage Modulator (the actual system, the issues, the motivation); System requirements and new concept; Proposed solid-state modulator; Prototype layout and experimental results Conclusions and future work 22 Set 2009 EPPC 09 CERN September /14 ISOLDE Target Voltage Modulator The On-Line Isotope Mass Separator facility uses the 1.4 GeV proton beam (up to 2 A ) from the PS-booster at CERN to bombard a target and produce a wide range of isotopes. The impacting proton beam intensively ionises the air. This ionisation perturbs the accelerating voltage because it represents a significant additional load on the power supply. To provide the needed acceleration, the target and ion source must be held at a precise voltage (60 kV1V), with respect to a grounded extraction electrode, if there is to be high mass resolution in the downstream separator. 22 Set 2009 EPPC 09 CERN September /14 During the critical period when protons strike the target the accelerating voltage is modulated to zero. This is acceptable provided that the stable accelerating voltage of 60 kV +/- 1 V is interrupted for less than 10 ms, so still allowing the detection of very short life-time radio isotopes. At present a custom-built positive 60 kV d.c. power supply (PS), I max