Radiation tolerant power converter controls

Abstract

The Large Hadron Collider (LHC) at the EuropeanOrganisation for Nuclear Research (CERN) is the world's mostpowerful particle collider. The LHC has several thousand magnets, both warmand super-conducting, which are supplied with current by power converters.Each converter is controlled by a purpose-built electronic module called aFunction Generator Controller (FGC). The FGC allows remote controlof the power converter and forms the central part of a closed-loop controlsystem where the power converter voltage is set, based on the converteroutput current and magnet-circuit characteristics. Some power converters andFGCs are located in areas which are exposed to beam-induced radiation. Thereare numerous radiation induced effects, some of which lead to a loss ofcontrol of the power converter, having a direct impact upon theaccelerator's availability.Following the first long shut down (LS1), the LHC will be able torun with higher intensity beams and higher beam energy. This is expected tolead to significantly increased radiation induced effects in materials closeto the accelerator, including the FGC. Recent radiation tests indicate thatthe current FGC would not be sufficiently reliable. A so-called FGClite isbeing designed to work reliably in the radiation environment in the post-LS1era.This paper outlines the concepts of power converter controls for machinessuch as the LHC, introduces the risks related to radiation and a radiationtolerant project flow. The FGClite is then described, with its key conceptsand challenges: aiming for high reliability in a radiation field.