A FAST 60 kV RESONANT CHARGING POWER SUPPLY FOR THE LHC
INFLECTORS

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INTRODUCTION
The European Laboratory for Particle Physics (CERN) is
designing a Large Hadron Collider (LHC) to be installed
in an existing 27 km circumference tunnel. The LHC requires
Injection Kicker Systems, devices for fast deflecting
the incoming particle beams onto the accelerator’s
circular trajectory. Two pulsed systems, of 4 magnets and
4 PFNs each, are required for injection[1,2].


POWER SEMICONDUCTOR SWITCH
If a thyratron turns-on erratically, during the recovery
period of the power semiconductor switch, the semiconductor
can be subjected to a forward dV/dt of 90 V/ms[4].
An SCR with suitable ratings for use in the RCS has a
turn-off time (tq) of typically several hundred microseconds.
During the recovery period, forward voltage cannot
be applied across the semiconductor switch without it
turning on, and an SCR has a limited capability to withstand
positive dV/dt when forward voltage is reapplied.

SNUBBER COMPONENTS
The purpose of the snubber circuit is to limit the dV/dt
across the GTO to an acceptable value. During normal
operation, the ECT is increased at a rate of 32 ms/mF of
the snubber capacitor value, and thus it is desirable to
minimise the value of the snubber capacitor.


TRANSFORMER TURNS RATIO
The charge time is determined approximately by the leakage
inductance of the transformer and the effective capacitance.