Cyclotron beam extraction by acceleration

2021

Flerov Laboratory of Nuclear Reaction of Joint Institute for Nuclear Research carries out the works under creating of FLNR JINR Irradiation Facility based on the cyclotron DC140. The facility is intended for SEE testing of microchip, for production of track membranes and for solving of applied physics problems. The DC140 cyclotron is intended for acceleration of heavy ions with mass-to-charge ratio A/Z within interval from 5 to 5.5 up to two fixed energies 2.124 and 4.8 MeV per unit mass. The intensity of the accelerated ions will be about 1 pmcA for light ions (A86) and about 0.1 pmcA for heavier ions (A>132). The system based on four main elements - electrostatic deflector, focusing magnetic channel, Permanent Magnet Quadrupole lens and steering magnet is used in the DC140 cyclotron for extraction of the accelerated beam. The design and simulation of the beam extraction system from the DC140 cyclotron are presented in this report.

Proc. of …, 2000

At IBA a compact 14 MeV H + cyclotron is under construc-tion. A special feature of this cyclotron is that there is no electrical deflector installed, ie the beam is self-extracted. This is achieved by a special shaping of the magnetic field, which shows a very steep fall-off near the outer ...

We discuss the possibility in principle of stripping extraction in combination with reverse bends in isochronous separate-sector cyclotrons (and/or fixed field alternating gradient accelerators). If one uses reverse bends between the sectors (instead of or in combination with drifts) and places stripper foils at the sector exit edges, the stripped beam has a reduced bending radius and it should be able to leave the cyclotron within the range of the valley—even if the beam is stripped at less than full energy. We are especially interested in stripping of H þ 2 , as it doubles the charge to mass ratio of the ions. However the method could be applied to other ions or ionized molecules as well. For the production of proton beams by stripping extraction of an H þ 2 beam, we discuss possible designs for three types of machines: First, a low-energy cyclotron for the simultaneous production of several beams at multiple energies—for instance 15, 30, and 70 MeV—thus allowing beam delivery on several isotope production targets. In this case it can be an advantage to have a strong energy dependence of the direction of the extracted beam. Second, we consider a fast variable-energy proton machine for cancer therapy that should allow extraction (of the complete beam) at all energies in the range of about 70 MeV to about 250 MeV into the same beam line. Third, we consider a high-intensity high-energy machine, where the main design goals are extraction with low losses, low activation of components, and high reliability. Especially if such a machine is considered for an accelerator driven system (ADS), this extraction mechanism has advantages: Beam trips by the failure of electrostatic elements could be avoided and the turn separation would be less critical, which allows operation at lower main cavity voltages. This would in turn reduce the number of rf trips. The price that has to be paid for these advantages is an increase in size and/or field strength compared to proton machines with standard extraction at the final energy.

PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268)

Experiments on beam extraction from the Nuclotron, a superferric heavy ion synchrotron, were carried out last year and in March, 2001. The resonance Qx=20/3, used for a horizontal betatron amplitude growth, provides beam entering the Electrostatic Septum deflector, where it obtains an initial deflection to avoid losses on the septum of the Lambertson Magnet. The latter bends the beam in the vertical plane to the level of the experimental halls. An extraction coefficient of about 70% and a spill time of 0.4s were obtained in the first experiments performed at the deuteron beam energy from 200MeV/amu to 1.5GeV/amu. Then, experiments on irradiation with C +6 and Mg +12 beams were performed on the external targets. The work, which permits one to improve the parameters of the extracted beam up to the projected ones, is discussed.

2017

According to the agreement between the Institute of Plasma Physics of the Chinese Academy of Sciences (ASIPP) in Hefei, China, and the Joint Institute for Nuclear Research (JINR), in Dubna, Russia, the project of superconducting isochronous cyclotron for proton therapy SC200 is under development at both sites. The cyclotron will provide acceleration of protons up to 200 MeV with maximum beam current of ~1 μA. Extraction system of the beam consists of electrostatic deflector and two passive magnetic channels. Electric field strength in deflector does not exceed 170 kV/cm, gradients of magnetic field in channels are in a range of 24 kG/cm. Both channels focus the beam in horizontal plane. Axial focusing of the beam is provided by edge magnetic field of the cyclotron. Results of the beam tracking inside extraction system are presented. Efficiency of the beam extraction was estimated for different amplitudes of the betatron oscillations in the accelerated beam. WORKING DIAGRAM OF CYCLOT...

Extensive Magnetic Field measurement of the K500 Superconducting Cyclotron has been completed. In this paper we report the beam dynamical calculations along the extraction system based on the measured magnetic field data. The beam matching to the external beam transport system, for different ion species spanning the operating region is also explored.

The purpose of this contribution is to report what has been learned from the operation of the Milan cyclotron, which in the past few years has been used mainly to accelerate H-ions in the energy range from 20 to 45 MeV.

Physical Review Accelerators and Beams, 2021

Beam stripping losses of H − ion beams by interactions with residual gas and electromagnetic fields are evaluated. These processes play an important role in compact cyclotrons where the beam is produced on an internal ion source, and they operate under high magnetic field. The implementation of stripping interactions into the beam dynamics code OPAL provides an adequate framework to estimate the stripping losses for compact cyclotrons such as AMIT. The analysis is focused on optimizing the high energy beam current delivered to the target. The optimization is performed by adjusting parameters of the ion source to regulate the vacuum level inside the accelerator and minimize the beam stripping losses.

The self-extraction cyclotron is a 14 MeV H+ machine from which the beam extracts without a deflector. This is achieved with a special shaping of the magnetic field. Detailed 3D magnetostatic models have been constructed of this cyclotron, in order to accurately calculate the extraction process. Shimming of removable pole tips has been used to isochronize the machine and to remove harmonic errors. A software simulation of the shimming has been made, in order to accelerate the convergence of this process. First extracted beam has been obtained. There is good agreement between the calculations and measurements. Results of TOSCA calculations, mapping and shimming are presented.

In IBA's C70 cyclotron, 2 modes of extraction are im- plemented: (i) a variable energy extraction by charge ex- change of negative ions, and (ii) a fixed energy extraction through an electrostatic deflector for positive ions. The stripping extraction will be implemented on two opposite poles allowing for a simultaneous dual beam extraction. At one side, the 2 extraction modes are linked by a strong ge- ometric condition, i.e. they must converge in a common switching magnet. Basically this is obtained by having both extractions occurring from the same pole, where the length of the gradient correcting pole shim and the set of azimuthal positions of the stripper foil are adjustable pa- rameters. The design of the extraction system is based on tracking studies in the deflection plane combined with beam optical calculations. Some constructional details of the extraction devices are given.