Conference Paper
Uniform beam intensity redistribution in the LENS nonlinear transport line
IUCF, Bloomington
DOI: 10.1109/PAC.2007.4440885 Conference: Particle Accelerator Conference, 2007. PAC. IEEE Source: IEEE Xplore

Conference Paper: Upgrade of the LENS Proton LINAC: Commissioning and results
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ABSTRACT: The Indiana University Cyclotron Facility is operating a low energy neutron source which provides cold neutrons for material research and neutron physics as well as neutrons in the MeV energy range for the neutron radiation effects studies. Neutrons are being produced by a 7 MeV proton beam incident on a beryllium target. Since the first commissioning of the LENS Proton Delivery System (PDS) in December 2004 its performance has been significantly improved. The RF system of the accelerator has been upgraded by replacing 350 kW 425 MHz 12 tube amplifiers with two Litton 5773 klystron RF tubes capable of running at 425 MHz and 1.25 MW. Since the commissioning of the klystrons, a proton current of 25 mA at 7 MeV and 0.6% duty factor has been successfully delivered to the beryllium target. A future part of this upgrade will introduce a new 6 MeV DTL section to increase proton beam energy from 7 to 13 MeV. The 3 MeV RFQ and 4 MeV DTL will be powered by one klystron and the 6 MeV DTL will be powered by the second klystron. The expected output is 25 mA and 13 MeV of proton current at 0.6% duty factor. A second target station has been added to allow separate source optimization for the two primary research programs (cold neutrons and radiation effects). Other upgrades include increasing the RF duty factor to 3% through the installation of a new power supply for the klystrons. In this contribution we discuss the results of the commissioning of the new RF system, second beamline and second target station, as well as improvement in the beam parameters after these upgrades. The future plans will also be outlined.Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007  [Show abstract] [Hide abstract]
ABSTRACT: It has been known that uniformization of a beam with a Gaussian profile is possible utilizing oddorder nonlinear focusing in the beam transport system, and this has recently been employed for uniform beam irradiation. Here, we have theoretically studied uniformization of the transverse beam profile using nonlinearfocusing forces produced by multipole magnets in detail. In the case where the nonlinear field of the multipole magnet is given by an infinite power series, all the oddorder multipole strengths required for uniformization of a Gaussian beam and the extent of the resultant uniform region have been expressed using the Twiss parameters. We have shown the principle of uniformization using evenorder nonlinear fields. We have also actually demonstrated the transformation of a beam with an asymmetric distribution into one with a uniform distribution by utilizing nonlinear focusing, especially with the sextupole and octupole fields. The validity of the formulas presented here was confirmed through particletracking simulations. A practical method to realize a uniform profile using beam collimation and octupole focusing is also presented.Review of Modern Physics 01/2007; 10(10). · 44.98 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We investigate the transformation of the transverse intensity distribution of a chargedparticle beam focused by one or two sextupole magnets in a beam transport line. It is expected, from the equation of transverse motion, that the beam is deflected toward one direction and thus deformed due to the secondorder force of the sextupole magnet. Such a sextupoleinduced deformation of the beam distribution has been studied analytically in detail. The beam centroid displacement and the change of the beam size are determined using the firstorder and secondorder moments of the intensity distribution function. In order to verify the theoretical consideration, numerical simulations and experiments were performed at the cyclotron facility of Japan Atomic Energy Agency. We experimentally demonstrate that an ion beam with a uniform transverse distribution can be formed using two sextupole magnets.Journal of the Physical Society of Japan 06/2012; 81(6):4501. · 2.09 Impact Factor
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