H. Deitinghoff

Four-rod-λ/2-RFQ for light ion acceleration☆

Abstract A simple type of RFQ structure with circular rods as electrodes has been developed in Frankfurt. The improved design uses a linear arrangement of supporting stems on a massive common bar. This linear rf structure consists of a chain of λ/2-line pairs and leads to an advantageously simple but nonetheless effective RFQ structure. With this stable cheap type of RFQ resonator preaccelerator prototypes have been built for light ions. New results of electrode and structure optimization and beam measurements are presented.

Properties of RFQ accelerators for ion implantation

Abstract While electrostatic accelerators are commonly used for ion implantation in research and industry, the progress in the development of efficient low energy rf accelerators has led to proposals for the application of radiofrequency quadrupoles (RFQ) structures in ion implanters. RFQs are rf structures which can efficiently accelerate ion beams to energies between 100 keV and several MeV. Features are a strong electrical rf-focusing which allows ion beam currents up to 10 mA and a compact and reliable system with the ion source only on a low 10–30 kV potential. Critical issues are the beam quality and the energy variation. The status of work on RFQ implanters in Frankfurt will be discussed.

The GSI high current RFQ prototype

Abstract A new high current injector (HSI) for the UNILAC and the SIS synchrotron for all ions up to uranium is planned at GSI. The spiral-RFQ accelerator accepts low energy (2.2 keV/u), high current (25 mA) beams at low charge states (U 2+ ) at an operating frequency of 27.1 MHz. Results of particle dynamics calculations and structure development for the first crucial part of the HSI-RFQ where all the bunch forming is done, is presented together with results of rf measurements and first beam tests.

Antiproton-proton mass comparison with a radio-frequency mass spectrometer

Abstract The experiment aims at the reduction of the upper limit on a hypothetical CPT violation in the antiproton-proton system. A radio-frequency mass spectrometer (RFMS) has been designed and built to make the comparison of the charge to mass ratios of p and p by measuring the ratios of the cyclotron frequencies of p and H− ions. At present, the RFMS is installed on-line to the LEAR facility at CERN. The resolving power has been found to be close to 3 × 105 and it still could be improved. A decelerating system (RFQ) has been installed in order to decelerate antiprotons from 2 MeV to 200 keV and to match as well as possible the acceptance of the spectrometer. It is presently under test and data taking should take place in 1992.

Properties of the GSI HLI-RFQ structure

The High Charge State Injector (HLI) RFQ (radio frequency quadrupole) for the GSI accelerator facility was designed for acceleration of U/sup 28+/ from 2.5 to 300 keV/U. The structure has been built and tuned. Properties of the RFQ structure and first experimental results are presented.<<ETX>>

Beam dynamics calculations for a prototype of a high-current heavy-ion RFQ

SummaryA 27 MHz heavy-ion RFQ for high currents at low ion energies has been designed and built for RF and beam tests. The accelerating structure is a 4-rod RFQ with spiral stems, developed in the institute. This RFQ will serve as a prototype for the first part of a large RFQ, which may be installed in the new high-current injector of GSI. Particle dynamics calculations were carried out to check the RFQ design with respect to beam quality and transmission in the bunch-forming process. Results of calculations are discussed including some requirements of HIIF injection. A description of the experimental set-up and first results from beam measurements will be given by Kipperet al. in this volume.

An Implantation System for MeV-mA Ion-Beams

A combination of high current and high energy ion beams satisfies the requirements of new applications in ion implantation experiments. High energies in the MeV – range are already used; for large area applications and high dose implantations also mA – current capabilities are needed to keep irradiation times in realistic and economical limits. The status of a high current, high energy acceleration system is discussed, which consists of a bucket ion source, an electrostatic injection system, a Radio Frequency Quadrupole (RFQ) accelerator, and a Spiral Loaded Cavity (SLC).

Commissioning of the new heavy ion injector at GSI

The Unilac has been upgraded by a new injector linac. It consists of an ECR source, a 108-MHz RFQ linac, and an interdigital H-type accelerator structure. Highly charged ions (such as U/sup 28+/) are extracted from the ion source and accelerated by the RFQ structure up to 300 keV/u. The IH tank accelerates with a very high RF efficiency up to an energy of 1.4 MeV/u. The commissioning of the injector is reported.<<ETX>>

Ar+-beam experiments with the high-current heavy-ion Spiral-RFQ at GSI☆

Abstract A Spiral-RFQ (Radio-Frequency Quadrupole Accelerator) has been built and operated with Ar + beams up to 8 mA. The aim of the experiment was the test of the RFQ for the High-Current Injector (HSI), which is planned at GSI to fill the Heavy Ion Synchrotron (SIS) up to its space charge limit. This Spiral-RFQ, a prototype for the HSI-RFQ, covers the crucial matching and bunching section of the electrodes. It is capable to produce ion beams of high brilliance, thus being a prototype for an implanter for heavy singly-charged metallic ions. The results of recent beam experiments with Ar + will be presented.

Design study of an energy-variable RF-accelerator for ion implantation

Abstract New applications in ion implantation (e.g. SIMOX, metal surface improvement) require a large penetration depth as well as very high implant doses. Both requirements — high ion energy and high beam current — can be satisfied at the same time by rf accelerators. In this paper we present a design of an rf acceleration system consisting of a Radio Frequency Quadrupole-(RFQ)-Accelerator and a Spiral Loaded Cavity. In contrast to common rf accelerators in this design the exit energy is variable over a large range in spite of a constant resonance frequency, which is achieved by splitting the RFQ into two parts. The first part serves for bunching and preacceleration of the ions, whereas the second part operates at different amplitudes and phases and accelerates the ions to various final energies. A continuous energy range is then obtained by the Spiral Loaded Cavity which is coupled to the RFQ. The design study has been carried out for the acceleration of 5–10 mA oxygen ions and an input energy of 50 keV. The projected output energies extend from 0.5 to 1.7 MeV.