TH2  —  Thursday Oral Session TH2   (02-Oct-08   11:00—12:20)

Chair: A. Chakrabarti, DAE/VECC, Calcutta

Paper Title Page
TH201 Charge State Boosters for Radioactive Ion Acceleration 745
 
  • F. Ames
    TRIUMF, Vancouver
 
 

For the post acceleration of radioactive ions produced at ISOL facilities the increase of the charge state is essential to reduce the A/q requirements of the accelerators. Many of those existing or proposed facilities are relying on the performance of charge state boosters of EBIS or ECRIS type. Although, in principle both types of sources can be used in pulsed or continuous mode operation an EBIS is better suited for pulsed beams whereas an ECRIS is most efficient in a continuous mode. The present state of the art with respect to existing data of both sources will be presented and potential future developments will be discussed. Latest results from the on line commissioning of a PHOENIX ECRIS charge breeder at ISAC will be presented.

 

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TH202 Heavy Ion Linac Booster at IUAC, New Delhi 749
 
  • A. Roy
    IUAC, New Delhi
 
 

The first module of the booster superconducting linear accelerator, consisting of a total of three modules, each having 8 quarter wave coaxial line bulk Nb resonators, has been commissioned at IUAC. During initial operation of the first linac module, the energy gain was found to be much lower due to various problems which are now identified and solved. After acceleration through the linac module and subsequent re-bunching using a superconducting Rebuncher, a 158 MeV silicon beam having pulse width of 400 ps was delivered to conduct nuclear physics experiments. The other two linac cryostats and the required 16 resonators to be installed in those two cryostats are in the final stage of fabrication. Work has progressed on a high current injector that would act as an alternate source of heavy ions for the superconducting linac. The first element of the high current injector is a high Tc superconducting magnet ECR source (PKDELIS) which would be followed by a room temperature radio frequency quadrupole accelerator and drift tube linac cavities. Prototypes of the RFQ working at 48.5 MHz, and that of the DTL working at 97 MHz, have been fabricated and are undergoing tests.

 

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TH203 Beam Compression in Heavy-Ion Induction Linacs 754
 
  • P.A. Seidl, A. Anders, F.M. Bieniosek, A.X. Chen, J.E. Coleman, J.-Y. Jung, M. Leitner, S.M. Lidia, B.G. Logan, P.N. Ni, P.K. Roy, K. Van den Bogert, W.L. Waldron
    LBNL, Berkeley, California
  • J.J. Barnard, R.H. Cohen, D.P. Grote
    LLNL, Livermore, California
  • J.A. Calanog
    UCB, Berkeley, California
  • M. Dorf, E.P. Gilson
    PPPL, Princeton, New Jersey
  • D.R. Welch
    Voss Scientific, Albuquerque, New Mexico
 
 

Funding: This work was supported by the Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, DE-AC52-07NA27344, DE-AC02-76CH3073.
The Heavy-Ion Fusion Sciences Virtual National Laboratory is pursuing an approach to target heating experiments in the Warm Dense Matter regime, using space-charge-dominated ion beams that are simultaneously longitudinally bunched and transversely focused. Longitudinal beam compression by large factors has been demonstrated in the LBNL Neutralized Drift Compression Experiment (NDCX) experiment with controlled ramps and forced neutralization. The achieved peak beam current and energy can be used in experiments that generate plasmas of warm dense matter. Using an injected 30 mA K+ ion beam with initial kinetic energy 0.3 MeV, axial compression leading to ~100X current amplification and simultaneous radial focusing to beam radii of a few mm have led to encouraging energy deposition approaching the intensities required for eV-range target heating experiments. We discuss the status of several improvements to the experiment and associated beam diagnostics that are under development to reach the necessary higher beam intensities.

 

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TH204 Student Prize Winner Talk - Twisted Structures and Their Application as Accelerating Structures 759
 
  • J.L. Wilson
    ORNL, Oak Ridge, Tennessee
 
 

Funding: This work has been sponsored by ORNL-SNS. The Spallation Neutron Source is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Normally, reactive loading is employed to construct accelerating cavities in order to slow the phase velocity of the electromagnetic wave. However, due to their non-uniform cross section, they tend to be difficult to machine, requiring complicated welding or brazing processes which increase the total cost. Although empty straight waveguides can only support faster-than-light propagation, empty twisted waveguides can support propagation at or below c. Because twisted structures have a uniform cross section in the transverse plane, they offer several potential advantages over dielectric loaded structures or other types of periodic structures. Of particular interest are twisted structures whose longitudinal cross section has been selected to resemble well-known accelerating structures, such as the iris-loaded accelerating structure and the TESLA type elliptical cavity. Comparisons are drawn between these conventional cavities and their twisted counterparts. Specifically, the phase velocity and dispersion relationship are discussed, the accelerating mode is found and analyzed, and R/Q is calculated. Design guidelines for the design of twisted structures are given.

 

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