224 research outputs found
Heavy-Ion Beam Acceleration of Two-Charge States from an Ecr Ion Source
This paper describes a design for the front end of a superconducting (SC) ion
linac which can accept and simultaneously accelerate two charge states of
uranium from an ECR ion source. This mode of operation increases the beam
current available for the heaviest ions by a factor of two. We discuss the 12
MeV/u prestripper section of the Rare Isotope Accelerator (RIA) driver linac
including the LEBT, RFQ, MEBT and SC sections, with a total voltage of 112 MV.
The LEBT consists of two bunchers and electrostatic quadrupoles. The
fundamental frequency of both bunchers is half of the RFQ frequency. The first
buncher is a multiharmonic buncher, designed to accept more than 80% of each
charge state and to form bunches of extremely low longitudinal emittance (rms
emittance is lower than 0.2 keV/u nsec) at the output of the RFQ. The second
buncher is located directly in front of the RFQ and matches the velocity of
each charge-state bunch to the design input velocity of the RFQ. We present
full 3D simulations of a two-charge-state uranium beam including space charge
forces in the LEBT and RFQ, realistic distributions of all electric and
magnetic fields along the whole prestripper linac, and the effects of errors,
evaluated for several design options for the prestripper linac. The results
indicate that it is possible to accelerate two charge states while keeping
emittance growth within tolerable limits.Comment: LINAC2000, MOD0
Multiple Charge State Beam Acceleration at Atlas
A test of the acceleration of multiple charge-state uranium beams was
performed at the ATLAS accelerator. A 238U+26 beam was accelerated in the ATLAS
PII linac to 286 MeV (~1.2 MeV/u) and stripped in a carbon foil located 0.5 m
from the entrance of the ATLAS Booster section. A 58Ni9+ 'guide' beam from the
tandem injector was used to tune the Booster for 238U+38. All charge states
from the stripping were injected into the booster and accelerated. Up to 94% of
the beam was accelerated through the Booster linac, with losses mostly in the
lower charge states. The measured beam properties of each charge state and a
comparison to numerical simulations are reported in this paper.Comment: LINAC2000, MOD0
Multiple-Charge Beam Dynamics in an Ion Linac
There is demand for the construction of a medium-energy ion linear accelerator based on superconducting rf (SRF) technology. It must be capable of producing several hundred kilowatts of CW beams ranging from protons to uranium. A considerable amount of power is required in order to generate intense beams of rare isotopes for subsequent acceleration. At present, however, the beam power available for the heavier ions would be limited by ion source performance. To overcome this limit, we have studied the possibility of accelerating multiple-charge-state (multi-Q) beams through a linac. We show that such operation is made feasible by the large transverse and longitudinal acceptance which can be obtained in a linac using superconducting cavities. Multi-Q operation provides not only a substantial increase in beam current, but also enables the use of two strippers, thus reducing the size of linac required. Since the superconducting (SC) linac operates in CW mode, space charge effects are essentially eliminated except in the ECR/RFQ region. Therefore an effective emittance growth due to the multi-charge beam acceleration can be minimized
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Physics design of front ends for superconducting ion linacs
Superconducting (SC) technology is the only option for CW linacs and is also an attractive option for pulsed linacs. SC cavities are routinely used for proton and H{sup -} beam acceleration above 185 MeV. Successful development of SC cavities covering the lower velocity range (down to 0.03c) is a very strong basis for the application of SC structures in the front ends of high energy linacs. Lattice design and related high-intensity beam physics issues in a {approx}400 MeV linac that uses SC cavities will be presented in this talk. In particular, axially-symmetric focusing by SC solenoids provides strong control of beam space charge and a compact focusing lattice. As an example, we discuss the SC front end of the H{sup -} linac for the FNAL Proton Driver
Application of ILC super conducting cavities for acceleration of protons
Beam acceleration in the International Linear Collider (ILC) will be provided by 9-cell 1300 MHz superconducting (SC) cavities. The cavities are designed for effective acceleration of charged particles moving with the speed of light and are operated on {pi}-mode to provide maximum accelerating gradient. Significant R&D effort has been devoted to develop ILC SC technology and its RF system which resulted excellent performance of ILC cavities. Therefore, the proposed 8-GeV proton driver in Fermilab is based on ILC cavities above {approx}1.2 GeV. The efficiency of proton beam acceleration by ILC cavities drops fast for lower velocities and it was proposed to develop squeezed ILC-type (S-ILC) cavities operating at 1300 MHz and designed for {beta}{sub G} = 0.81, geometrical beta, to accelerate protons or H{sup -} from {approx}420 MeV to 1.2 GeV. This paper discusses the possibility of avoiding the development of new {beta}{sub G} = 0.81 cavities by operating ILC cavities on 8/9{pi}-mode of standing wave oscillations
Feasibility study of a 2 GeV superconducting linac as injector for the CERN PS
This preliminary feasibility study is based on the availability of the CERN LEP2 superconducting RF system after LEP de-commissioning. The option that is explored is to use this system as part of a high energy H- linac injecting at 2 GeV into the CERN PS, with the aim of reliably providing at its output twice the presently foreseen transverse beam brightness at the ultimate intensity envisaged for LHC. This requires the linac to be pulsed at the PS repetition rate of 0.8 Hz with a mean beam current of 10 mA which is sufficient for filling the PS in 240 ms (i.e. about 100 turns) with the ultimate intensity foreseen for injection for the LHC. The linac is composed of two RFQs with a chopping section, a room temperature DTL, a superconducting section with reduced beta cavities up to 1 GeV, and a section of LEP2 cavities up to 2 GeV. This study deals, in particular, with the problems inherent in H- acceleration up to high energy and in the pulsed operation of SC cavities. Means for compensating microphonic vibrations in the SC cavities are considered, with the aim of reducing the final overall energy spread to the tight requirements for injection into a synchrotron. Other possible applications of such a machine are also briefly reviewed, that make use of its potential for working at a higher duty cycle than required for LHC alone
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Multi-Cell Reduced-Beta Elliptical Cavities for a Proton Linac
A superconducting cavity has been designed for acceleration of particles traveling at 81% the speed of light ({beta} = 0.81). The application of interest is an 8 GeV proton linac proposed for a Fermilab upgrade; at present, the cavity is to be used from 420 MeV to 1.3 GeV. The cavity is similar to the 805 MHz high-{beta} cavity developed for the Spallation Neutron Source Linac, but the resonant frequency (1.3 GHz) and beam tube diameter (78 mm) are the same as for the {beta} = 1 cavities developed for the TESLA Test Facility. Four single-cell prototype cavities have been fabricated and tested. Two multi-cell prototypes have also been fabricated, but they have not yet been tested. The original concept was for an 8-cell cavity, but the final design and prototyping was done for 7-cells. An 11-cell cavity was proposed recently to allow the cryomodules for the {beta} = 0.81 cavity and downstream 9-cell {beta} = 1 cavities to be identical. The choice of number of cells per cavity affects the linac design in several ways. The impact of the number of cells in the 8 GeV linac design will be explored in this paper. Beam dynamics simulations from the ANL code TRACK will be presented
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