| Paper | Title | Page |
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| THAY01 | Progress in induction synchrotrons | 0 |
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| THAY02 | Progress in slip stacking and barrier-RF | 293 |
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| Slip stacking for pbar production has been operational since December 2004 and increased the beam intensity on pbar target more than 60%. We plan to use slip stacking for NuMI neutrino experiment for effectively increasing intensity to NuMI target by about a factor two in a 2.2 sec MI cycle. In parallel with slip stacking, we plan to study fast momentum stacking using barrier buckets. One barrier rf system has been installed and tested, and second system is being installed during the current shutdown. | ||
| THAY03 | Challenges for hadron (and leptons) nonscaling FFAGs | 303 |
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| The concept of Fixed-Field Alternating-Gradient (FFAG) accelerators was introduced about a half century ago. Few prototypes were built soon after and successfully placed in operation. Nevertheless, because of the perceived complexity of the early model magnets and design, the concept was soon abandoned in favor of cyclotrons, synchrotrons and linacs. It was subsequently occasionally revived for possible application as spallation neutron sources; but it was only recently that, because of the need of fast acceleration of muons, that FFAGs were re-considered and studied with more attention. Two prototypes were eventually built and operated at KEK for the acceleration of Protons. The interest indeed soon switched more steadily toward acceleration of protons (and electrons) as application for high-power proton drivers and medical accelerators. The paper describes the design procedure of a proton FFAG accelerator that employs a Non-Scaling lattice and exposes the main inherent issues, namely: the crossing of multiple resonances, space-charge at injection, and the fast acceleration rate that may impose limitations on the RF cavity hardware. | ||
| THAY04 | Review of high-brightness proton and ion acceleration using pulsed lasers | 319 |
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In the last few years, intense research has been conducted on laser-accelerated ion sources and their applications. These sources have exceptional properties, i.e. high brightness and high spectral cut-off, high directionality and laminarity, short burst duration. We have shown that for proton energies >10 MeV, the transverse and longitudinal emittance are respectively <0.004 mm-mrad and <10-4 eV-s, i.e. at least 100-fold and may be as much as 104-fold better than conventional accelerators beams. Thanks to these properties, these sources allow for example point-projection radiography with unprecedented resolution. They also open new opportunities for ion beam generation and control, and could stimulate development of compact ion accelerators for many applications. We have shown [*] that there is an optimum in the laser pulse duration of ~200 fs-1 ps, with a needed laser energy level of 30 to 100 J, in order to achieve e.g. 200 MeV energy protons. Also, as, for such applications beam control is an essential requirement, we have developed [**] an ultra-fast laser-triggered micro-lens that allows tuneable control of the beam divergence as well as energy selection.
[*] J. Fuchs et al., Nature Physics 2, 48 (2006). |
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| THAY05 | Progress in Accelerator R&D for High Energy Density Physics and Warm Dense Matter Applications | 0 |
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The research objectives of the U. S. Heavy Ion Fusion Science Virtual National Laboratory include: achieving warm dense matter conditions on near-term experiments and addressing the top-level scientific question: "How can heavy ion beams be compressed to the high intensities required for creating high energy density matter and fusion ignition conditions?" The accelerator R&D effort is focused on the Neutralized Drift Compression Experiment (NDCX), studies of electron cloud, and advanced theory and simulation. NDCX has achieved a longitudinal compression factor of 60 in a background plasma. Simulations using the LSP code agreed well the experiments. A kinetic model showed that the Vlasov equation possesses a class of exact solutions describing both transverse and longitudinal compression. Extensive measurements of electron cloud were carried out on a high brightness beam. An algorithm for large time-step advancement of electron orbits and a suite of models for electrons, gas, and wall interactions were implemented in the WARP 3D code. Electron-ion two-stream instabilities and the temperature-anisotropy instability have been simulated using a low-noise delta-f method by the BEST code.
For the U. S. Heavy Ion Fusion Science Virtual National Laboratory |
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| THAY06 | Fast-Pulsed Superconducting Magnets | 324 |
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| Up to now only one synchrotron (Nuclotron at JINR, Dubna) has been equipped with fast-pulsed superconducting magnets. The demand for high beam intensities leads to the requirement of fast-pulsed, periodically cycling magnets for synchrotrons and fast-pulsed magnets for storage rings. An example is FAIR (Facility for Antiproton and Ion Research) at GSI, which will consist of two synchrotrons in one tunnel and several storage rings. The fast field ramp rate and repetition frequency introduce many magnet design problems and constraints in the operation of the accelerator. Persistent currents in the superconductor and eddy currents in wire, cable, iron and vacuum chamber reduce the field quality and generate cryogenic losses. A magnet lifetime of 20 years is anticipated, resulting in up to 108 magnet cycles. Therefore special attention has to be paid to magnet material fatigue problems. R&D work is being done in collaboration with many institutions, to reach the requirements mentioned above. Model dipoles were built and tested. The results of the R&D are reported. The advantages of the use of low field, fast pulsed superconducting, compared to resistive, magnets will be discussed. | ||
| THAY07 | SC Spoke Cavity | 337 |
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| Superconducting (SC) TEM-class spoke cavities have been an area of active research during the past decade with application to cw and pulsed ion linacs required for proposed facilities world-wide. Single- and multi-spoke geometries have been developed for use with ions over the full mass range and with velocities 0.2 < v/c < 0.8. Spoke cavities for this range, generally designed for 4 K operation, have several advantages over 2 K elliptical-cell cavities stemming mostly from the lower operating frequency. However, recent spoke-cavity results in 2 K operation, based on new and evolving cavity processing techniques such as clean assembly and hydrogen degassing, show very low rf losses even for high surface fields (EPEAK ~30 MV/m) required in operations. 2K results indicate even higher voltage gains per cavity with reduced heat loads are possible. Other implications of 2 Kelvin spoke cavity operation for ion linacs are discussed. |