The radiofrequency quadrupole maurizio vretenar cern, geneva, switzerland abstract radiofrequency quadrupole rfq linear accelerators appeared on the accelerator scene in the late 1970s and have since revolutionized the domain of lowenergy proton and ion acceleration. Vacuum properties and operation stability of the radio. Physics design of rfq for isns application has been carried out for 10% maximum duty factor. In a quadrupole mass spectrometer the quadrupole is the mass analyzer the component of the. It examines soviet research on 1 the radio frequency quadrupole rfq and 2 the alternating phase focusing apf methods of accelerating and focusing proton and heavy ion beams in linear accelerators, as reported in soviet opensource technical publications. Design, development, and acceleration trials of radio. They are also called radio frequency rf traps or paul traps in honor of wolfgang paul, who invented the device and shared the nobel prize in physics in 1989 for this work. It is similar in concept to a quadrupole mass analyser but its purpose is to accelerate a singlespecies beam rather than perform mass spectrometry on a multiplespecies beam. A device is used to inject ions from the ion source to the accelerator, causing the. The idea of a radio frequency quadrupole accelerator core. In this embodiment, an ion source provides ions to a radio frequency quadrupole linear accelerator comprising electrodes. Singh 1 1bhabha atomic research centre, mumbai, india 400085 2fermi national accelerator laboratory, batavia, il 60510, usa.
The injector has been designed to optimize the beam parameters to meet. The linac provides a 400mev negative hydrogen ion beam to the rcs. Beam dynamics and electromagnetic studies of a 3 mev, 325. External resonance circuit type radio frequency quadrupole. The radiofrequency quadrupole rfq linac structure is being developed for the acceleration of lowvelocity ions. Radio frequency quadrupole rfq linac ion linac systems. In the cw operating mode, the proposed rfq design adopted the conventional fourvane structure. It is also known as a transmission quadrupole mass spectrometer, quadrupole mass filter, or quadrupole mass spectrometer. The rippled four bar configuration provides simultaneous forward linear acceleration and strong quadrupole focusing by alternating the voltage as the rf field switches at the resonant frequency of the cavity. Key features of this accelerator are high current 100 ma, low emittancegrowth beam propagation, cw operation, high efficiency, and minimal maintenance downtime. A cw high power linear accelerator can only work with very low particle losses and structure activation. The first radio frequency quadrupole accelerator rfq was demonstrated in protvino, russia, in 1972. We present the beam dynamics and electromagnetic studies of a 3 mev, 325 mhz h. We show the design results of beam dynamics on the injector for highintensity proton accelerators.
A power source is used to apply radio frequency alternating currents to the electrodes. Radiofrequency quadrupole rfq linear accelerators appeared on the accelerator scene in the late 1970s and have since revolutionized the domain of lowenergy proton and ion acceleration. An ion or a charged particle is accelerated by the electric field generated by a static electric potential or a radio frequency rf electromagnetic microwave. During high power operation of rfq, rfinduced heating would result in temperature. Schempp johann wolfgang goethe university, frankfurt am main, germany abstract radiofrequency quadrupole rfq linacs are efficient, compact, lowenergy ion structures, which have found numerous applications. A deuteron radio frequency quadrupole rfq accelerator has been designed, fabricated, and tested at barc, which will be used for neutron generation. A radiofrequency quadrupole rfq is a linear accelerator component generally used at low beam energies, roughly 50kev to 3mev. The focusing as well as the bunching and acceleration are performed by a radio frequency rf electric field. Rf design of radiofrequency quadrupole accelerator for. Multiphysics analysis for thermal management of a 3 mev. The idea of a radio frequency quadrupole accelerator.
Citeseerx document details isaac councill, lee giles, pradeep teregowda. Attention is then focussed on the beam dynamics design in decelerating rfqs and, in particular, on how to cope with the intrinsic. We have followed a design approach, where the emittance growth and the losses are minimized by keeping the tune depression ratio larger than 0. Introduction in this chapter, issues of applying the radio frequency quadrupole rfq accelerator to ion. In the rfq, the use of rf electric fields for radial focusing, combined with special programming of the bunching, allows highcurrent dc beams to be captured and. Electrostatic accelerator is the simplest device to accelerate the ions. Compact and critical structure, where beam dynamics, rf and mechanical aspects are closely interconnected. Unlike other conventional rf linear accelerators, the electromagnetic mode used for its operation is not the lowest frequency mode supported by the. Introduction to accelerators for boron neutron capture. The rfq makes the reliable production of unprecedented ion beam intensities possible within a compact radio frequency rf resonator which concentrates the three main functions of the lowenergy linac. The quadrupole mass analyzer qms is one type of mass analyzer used in mass spectrometry. The machining coordinates for horizontal vane as a function of position z. Rf design of radio frequency quadrupole accelerator for heavy ion medical machine. The radiofrequency quadrupole a new linear accelerator.
Recent experimental tests have confirmed its expected performance and have led to an increased interest in a wide range of possible applications. Then, the transverse and longitudinal particle dynamics are treated. Low cost radio frequency power sources for accelerator applications low cost, highly efficient rf power sources are needed to power accelerators. Multipurpose neutron generators based on the radio. At low energy, the radio frequency quadrupole rfq is an accelerator element that is very. Thus, a 10 ghz scaled model is designed, manufactured and measured. This paper presents an overview of rfq working principles, highlights the relevant parameters and summarises the different design approaches for the high, medium and low intensity cases. In the rfq, the use of rf electric fields for radial focusing, combined with special programming of the bunching, allows highcurrent dc beams to be captured. Beam dynamics design of a radiofrequency quadrupole and a. In an external resonance circuit type rfq accelerator comprising undulated quadrupole electrodes and a separate radio frequency resonance circuit for generating a radio frequency high voltage to be supplied to said electrodes, the improvement wherein said undulated quadrupole electrodes and at least a part of metallic supports for supporting said electrodes and. Lastly, an electron radiofrequency quadrupole erfq at 91 ghz is designed and beam computations are performed with the particleincell pic method. These compact linear accelerators can produce from 10 8 to more than 10 neutronssecond using either proton or deuteron beams to bombard beryllium targets. As the name implies, it consists of four cylindrical rods, set parallel to each other. Radio frequency quadrupole rfq 1 radio frequency quadrupole rfq s.
The radio frequency quadrupole is a linear accelerator which focuses, bunches and accelerates a continuous beam of charged particles with high e fficiency and preserving the emittance. Subnanosecond single ion beam pulses are generated by means of one embodiment of the invention. The radio frequency quadrupole rfq linear accelerator is an accelerator that efficiently focuses, bunches and accelerates a high intensity dc beam from an ion source, for various applications. The injector system consists of a 325mhz rfq radiofrequency quadrupole accelerator and a 325mhz dtl drift tube linac accelerator. The injector can be utilized in a medical proton linac and accelerator driven system. They exhibit long lifetimes at full output, as there is little target or beam degradation. In this section, electricstatic accelerators are explained.
Since then many rfqs have been built worldwide for a variety of applications in research, industry and medicine. A 268 mhz, cw radio frequency quadrupole rfq linac section and klystrode based rf system were. Ion linac systems rfq linac is an extremely efficient rf accelerating structure for lowenergy ions. It is used as a component of a mass spectrometer or a trapped ion quantum computer.
For beam power upgrade, a new radiofrequency quadrupole rfq was designed to increase the peak beam current from 30 to 50 ma. We present multiphysics design studies for thermal management of a 325 mhz 3 mev radio frequency quadrupole rfq structure for the front end of 1 gev proton linac for proposed indian spallation neutron source isns. Neutron generators based on the radio frequency quadrupole accelerator are now used for a variety of applications. Radio frequency quadrupole and alternating phase focusing.
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