The injection bumper system for Leir

Abstract

To satisfy the ion beam luminosity requirements for CERN's future Large Hadron Collider (LHC), a small accumulator, the Low Energy Ion Ring (LEIR), is being built in the injector chain of accelerators. LEIR will use a combined longitudinal and transverse multi-turn injection scheme which requires a bumper system comprising four individually pulsed dipole magnets. The paper discusses the bumper system, in particular the power supplies which will produce a pulsed current linearly decreasing from 1.2kA to zero in a time variable between 120µs and 300µs. Each power supply employs a primary discharge circuit, comprising a storage capacitor, an IGBT switch and the magnet load inductance, to establish the peak current, and a free-wheel circuit in parallel with the magnet, comprising a diode and capacitor, to produce the linear current slope. A novel feature of the circuit is the use of a variable bias voltage on the free-wheel capacitor, allowing continuous variation of the slope duration. THE INJECTION BUMPER SYSTEM FOR LEIR A. Fowler AB Department, CERN CH-1211 Geneva 23, Switzerland AbstractTo satisfy the ion beam luminosity requirements for CERN's future Large Hadron Collider (LHC), a small accumulator, the Low Energy Ion Ring (LEIR), is being built in the injector chain of accelerators. LEIR will use a combined longitudinal and transverse multiturn injection scheme that requires a bumper system comprising four individually pulsed dipole magnets.The paper discusses the bumper system, in particular the power supplies that will produce a pulsed current linearly decreasing from 1.2 kA to zero in a time variable between 120 µs and 300 µs. Each power supply employs a primary discharge circuit, comprising a storage capacitor, an IGBT switch and the magnet load inductance, to establish the peak current, and a free-wheel circuit in parallel with the magnet, comprising a diode and capacitor, to produce the linear current slope. A novel feature of the circuit is the use of a variable bias voltage on the free-wheel capacitor, allowing continuous variation of the slope duration.

IGBT Applications

“…Another application of IGBTs in the LHC at CERN is to drive the current in four bumper magnets in the Low Energy Ion Ring (LEIR) [34]. The bumper magnets require a peak current of 1200 A that decreases linearly to zero in a time period ranging from 120 to 300 ms.…”