T. Fowler

160 MeV H - injection into the CERN PSB

The H- beam from the proposed LINAC4 will be injected into the four existing rings of the PS Booster at 160 MeV. A substantial upgrade of the injection region is required, including the modification of the beam distribution system and the construction of a new H- injection system. This paper discusses beam dynamics and hardware requirements and presents the results of optimisation studies of the injection process for different beam characteristics and scenarios. The resulting conceptual design of the injection region is presented, together with the main hardware modifications and performance specifications.

The power supply for a medical synchrotron Beam Chopper System

In this paper the power supply for the Beam Chopper System of a medical synchrotron is presented. The four, series connected beam chopper magnets, which are placed on the extraction line, are used for blanking the beam both during routine operation and for emergency. To let the beam pass the magnets need to be energized with a current, proportional to the beam energy, whose maximum value is 650 A. Rise and fall time shall be less than 260 mus, while the flat-top can be maintained for an arbitrary long time. The power supply is composed of an high voltage part, which is in charge of the rising and falling current ramp, and of a low voltage part, which is in turn responsible for the current flat top. The paper presents details about the design and experimental results measured on the actual device.

The power supply for the beam chopper magnets of a medical synchrotron

The ongoing design of the power supply for the beam chopper magnets of a medical synchrotron is presented. The four, series connected beam chopper magnets, which are placed on the extraction line, are used for blanking the beam both during routine operation and for emergency. To let the beam pass the magnets need to be energized with a current, proportional to the beam energy, whose maximum value was calculated to be about 650A. The required current should be reached from zero in less than 260μs and then can be maintained for an arbitrary long time. Finally is should fall back to zero in less than 260μs. The power supply is composed of an high voltage part (2.9kV), which is in charge of the rising and falling current ramp and of a low voltage part (60V) which is in turn responsible for the current flat top.

Design of the modulator for the CTF3 tail clipper kicker

The goal of the present CLIC Test Facility (CTF3) is to demonstrate the technical feasibility of specific key issues in the CLIC scheme. The extracted beam from the combiner ring (CR), of 35 A in magnitude and 140 ns duration, is sent to the new CLic EXperimental area (CLEX) facility. A tail clipper (TC) is required, in the CR to CLEX transfer line, to allow the duration of the extracted beam pulse to be adjusted. It is proposed to use a stripline kicker for the TC, with each of the deflector plates driven to equal but opposite potential. The TC kick must have a fast rise-time, of not more than 5 ns, in order to minimize uncontrolled beam loss. Several different options are being investigated to meet the demanding specifications for the modulator of the TC. This paper discusses options considered for the fast, high voltage, semiconductor switches and shows results of initial tests on the switches.

Pulse Forming Network Conceptual Design for the Proposed PS Multi-Turn Extraction System

A five-turn continuous extraction system is currently used to transfer the proton beam from the CERN Proton Synchrotron (PS) to the Super Proton Synchrotron (SPS). The present approach, which is based on cutting the filament beam into 5 slices using an electrostatic septum, causes inherent losses of about 15% of the extracted beam and non optimal betatronic matching for the different slices in the receiving machine. This will be an even more serious drawback when the beam intensity needs to be increased for the CERN Neutrinos to Gran Sasso (CNGS) facility. To overcome this, a novel multi-turn extraction (MTE) scheme has been proposed, where the beam is separated, prior to extraction, into a central beam core and four islands by means of elements such as sextupoles and octupoles. Each beamlet is ejected using fast kickers and a magnetic septum. For the MTE kickers, two new pulse generators are required, each containing a lumped element Pulse Forming Network (PFN) of 12.5 Omega, 80 kV and 10.5 mus. For cost reasons, it is envisaged to re-use existing 15 Omega transmission line kicker magnets. The PFN characteristic impedance deliberately mismatches that of the magnets to allow a higher maximum available kick. The PFN design has been optimized such that undesirable side-effects of the impedance mismatch, on kick rise-time and flat-top, remain within acceptable limits. The conceptual design for the MTE PFN is presented.

Kickers used for bunched e/sup +//e/sup -/ beam transfer in the CERN PS complex

The main characteristics and operating experiences of the 100-Hz pulsed injection kicker and the eight pulse burst ejection kicker systems installed in the EPA (Electron Positron Accumulator) ring are described. Delay line type magnets placed in vacuum tanks are excited by fast pulses generated from thyratron-switched PFNs (pulse forming networks). Deflecting fields of 52 ns FWHH with rise and fall times of 28 ns are achieved. Up to eight e/sup +/ or e/sup -/ bunches are injected into the PS (Proton Synchrotron) in a single turn. For each particle type, one delay-line-type magnet is used. Both magnets are excited from the same PFN, switched at either end, with a pulse of 2000 A and 2 mu s duration. A transfer efficiency between EPA and PS exceeding 90% has been achieved.<<ETX>>

PPPS-2013: Abstract a digital hardware design to control and monitor a high voltage pulsed power supply for the electric field fast deflector of the medaustron hadron therapy facility

Summary form only given. The MedAustron ion-therapy centre for cancer treatment and research will comprise a particle accelerator facility using a synchrotron for the delivery of protons and light-ions. The Low Energy Beam Transfer line (LEBT) between the ion source and the synchrotron contains an electric field fast deflector (EFE) to chop the continuous beam arriving from the source. By using an electric field the beam is deviated onto a Faraday Cup (FC). A pulsed power supply (PKF) with high voltage MOSFET switches connected in a push-pull configuration and a specified voltage of ± 3.5 kV is used for charging and discharging the electrodes of the EFE. This allows beam passage for multi-turn injection into the synchrotron for variable pulse durations from 500 ns up to d.c. with rise and fall times of less than 300 ns between 90 % of peak voltage and a ± 1 V level. To verify the switching to the ± 1 V level and subsequent flat bottom pulse quality a large dynamic range monitoring circuit is implemented in the PKF. A hardware design, based on a complex programmable logic device (CPLD), is used to control and monitor the pulsed power supply. An interface to a supervisory control unit is provided by the use of a programmable logic controller (PLC) to switch between different states of the PKF and to report errors detected by the monitoring circuit. This paper presents the design decisions made for the digital hardware design on the CPLD and their results.

PPPS-2013: Design and development of a 6.25 kV / 1 kA PFN to supply the new PS Booster distributor magnets

Linac4 is an H- ion linear accelerator, intended to replace Linac2 as injector to the PS Booster (PSB). In order to distribute the 160 MeV beam from Linac4 to the four rings of the PSB, new distributor magnets (BI.DIS) and magnetic septa (BI.SMV) need to be built. The proposed distribution scheme requires the construction of five new pulse generators, of Pulse Forming Network (PFN) type, to double the magnitude of the BI.DIS field pulse and to increase the maximum duration of the pulse from 140 μs to 620 μs.

The CERN PS multi-turn extraction based on beam splittting in stable islands of transverse phase space

The PS Multi-Turn Extraction Study Group M. J. Barnes*, O. E. Berrig, A. Beuret, J. Borburgh, P. Bourquin, R. Brown, J.-P. Burnet, F. Caspers, J.-M. Cravero, T. Dobers, T. Fowler, S. Gilardoni, M. Giovannozzi (Study Group Leader), M. Hourican, W. Kalbreier, T. Kroyer, F. di Maio, M. Martini, V. Mertens, E. Métral, K.-D. Metzmacher, C. Rossi, J.-P. Royer, L. Sermeus, R. Steerenberg, G. Villiger, T. Zickler