LIBD on LBDSmeeting Viliam Senaj 04/02/2014

MKB test MKB vacuum level satisfactory for beginning of HV test: – B1: between 3.1x10 -7 and 5.7x10 -7 (new tank) mbar – B2: between 1x10 -7 and 4.1x mbar (new tank 3x10 -7 ); today problem with 1 pump – probably HV connector on pump faulty – reparation ongoing Digital interlock levels reduced down to 1x10 -5 ; Still some problems of interlock status and vacuum levels seen by Wincc to be solved

MKD test Generators B&J /B2 : Slow control (EC) + HV test (FPS) – done Control on Gen A/B2 (missing current in main switches) – nothing unusual found: suspected high current sparking (~12 kA missing) Sparking activity of all generators on B2 will be remeasured and if needed measures taken (FPS) Installing of saturable ferrites on both beams under preparation: reduction of T_rise and dumping of the spark induced ringing between GTO stacks (FPS) Installing of the additional resistances between GTO cathode and gate with the goal to reduce mutual coupling between GTOs (FPS)

Dumping effect of saturable ferrite Perturbation on one stack simulating sparking – self-resonance between two stacks at ~ 2MHz with low dumping Same test with saturable ferrites on top of each stack: reduction of self-resonance frequency down to ~ 250 kHz at which the used ferrite has the highest losses. Higher scope sensitivity!

Effect of saturable coil on T_rise Gain of ~ 50 ns on T_rise with Uptu=3 kV