R. Lambiase

1400 A, +/-900 V peak pulse switch mode power supplies for SNS injection kickers

This paper describes simulation and experimental results for a 1400 A, /spl plusmn/900 V peak rated, switch mode power supply for SNS Injection Kicker Magnets. For each magnet (13 m/spl Omega/, 160 /spl mu/H), the power supply must supply controlled pulses at 60 Hz repetition rate. The pulse current must rise from zero to maximum in less than 1 millisec in a controlled manner, flat top for up to 2 millisec, and should fall in a controlled manner to less than 4 A within 500 /spl mu/s. The low current performance during fall time is the biggest challenge in this power supply. The simulation results show that to meet the controlled fall of the current and the current ripple requirements, voltage loop bandwidth of at least 10 kHz and switching frequency of at least 100 kHz are required. To achieve high power high frequency switching with IGBT switches, a series connected topology with three phase shifted (0/spl deg/, 60/spl deg/ & 120/spl deg/) converters each with 40 kHz switching frequency (IGBT at 20 kHz), has been achieved. In this paper, the circuit topology, relevant system specifications and experimental results that meet the requirements of the power supply are described in detail. A unique six pulse SCR rectifier circuit with capacitor storage has been implemented to achieve minimum pulse width to meet required performance during current fall time below 50 A due to the very narrow pulse width and nonlinearity from IGBT turn-on/off times.

Design, development, and construction of SNS extraction fast kicker system

The SNS accumulator ring extraction fast-kicker system was design, developed, and prototype tested at the Brookhaven National Laboratory. Its construction has just begun. The system is for one-turn fast extraction ejecting proton beam from the ring into the extraction septum gap and further deflecting into the ring-to-target beam transport line. The system consists of fourteen high-voltage modulators, their local control and auxiliary systems, and fourteen window frame magnet sections. High-voltage transmission cables will be used for pulse transmission from modulators to their corresponding magnet sections. The high-voltage and high-current pulse has a rise time about 200 ns, a pulse duration about 700 ns, and a current amplitude above 2500 Amp per modulator. The modulator design features a Blumlein Pulse-Forming-Network with ultra-low inductance high energy storage pulsed capacitors, an ultra-fast high-power hollow anode thyratron, a parallel resistor stack for low beam-impedance termination, and a saturable inductor stack for beam current isolation and pulse rise time sharpening. This design is driven by the considerations of low beam loss, high maintainability and reliability. All high voltage modulators will be placed outside the ring tunnel and the system is immune to one-kicker failure. In addition, the enlarged magnet aperture can accept all four working points. The design concept has been successfully proven by the prototype test. The techniques, considerations, and other related issues of the system design, development and construction are discussed in this paper.

RHIC magnet electrical system

The RHIC magnet electrical system consists primarily of the power converters that are used to energize the superconducting magnets in the collider ring, the power distribution system (both room temperature and superconducting) to deliver that power from the converters to the magnets, a detection system to monitor for quenches in the magnets and superconducting cables, and a protection system to remove power from the superconductors if a quench is detected. This system also has major interfaces with the Control System for commands, status monitoring, current setting and analog monitoring of the power supplies, and with Conventional Facilities for power distribution of the mains at and below the 480VAC level.

Mechanical design of a ferrite-based injection kicker for SNS accumulator ring

Two sets of kickers, 4 pulsed dipoles in each set, will be used in the SNS accumulator ring to create a dynamic orbit bump for injection process. These kickers are designed as large aperture, window frame magnets. The design of these 8 kickers has been completed. The first article kicker has been assembled and is being tested. In this paper we discuss the mechanical design criteria for these kickers, the layout in the accumulator ring, the magnetic field requirements and the ferrite based magnet field analysis, the eddy current and thermal considerations in the choice of ceramic vacuum chamber and its implementation. Also we discuss a wedge shaped clamp which was designed to reduce the vibration in the coil when powered at the 60 Hz repetition rate.

RHIC power supplies: lessons learned from the 1999-2001 RHIC runs

The Relativistic Heavy Ion Collider (RHIC) was commissioned in 1999 and 2000. The two RHIC rings require a total of 933 power supplies (PSs) to supply currents to highly inductive superconducting magnets. These units function as 4 main PSs, 237 insertion region (IR) PSs, 24 sextupole PSs, 24 Gamma-T PSs, 8 snake PSs, 16 spin rotator PSs, and 620 correction PSs. PS reliability in this type of machine is of utmost importance because the IR PSs are nested within other IR PSs, and these are all nested within the main PSs. This means if any main or IR PS trips off due to a PS fault or quench indication, then all the IR and main PSs in that ring must follow. When this happens, the Quench Protection Assemblies (QPAs) for each unit disconnects the PSs from the circuit and absorb the stored energy in the magnets. Commissioning these power supplies and QPAs was and still is a learning experience. A summary of the major problems encountered during these first three RHIC runs will be presented along with solutions.