| Paper |
Title |
Page |
| MOPAS049 |
Ceramic-Supported Traveling-Wave Structures for SNS Fast Beam Chopper
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545 |
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- S. S. Kurennoy
LANL, Los Alamos, New Mexico
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The current structure for the fast 2.5-MeV beam chopper for the Spallation Neutron Source (SNS) project was originally developed* to provide rise and fall times around 1 ns. The structure is based on the meander-folded notched strip line with low-dielectric-constant supports and metal separators. Since then the requirements of the chopper rise-time has been significantly relaxed, up to 10 ns, as a result of beam dynamics simulations and to simplify the voltage pulse generators. In addition, initial runs with the beam showed that this structure was prone to damage when accidental beam spills occurred. We suggest alternative meander structures for the SNS chopper that employ high-dielectric-constant substrate (e.g., alumina). Time-domain simulations show their electromagnetic performance to be well within the requirements, while their resistance to beam spills and thermal properties are expected to be much better and fabrication significantly simpler.
* S. S. Kurennoy and J. F. Power, EPAC 2000 (Vienna, Austria, 2000), 336.
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| FROBC03 |
Efficient Accelerating Structures for Low-Energy Light Ions
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3824 |
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- S. S. Kurennoy, L. Rybarcyk, T. P. Wangler
LANL, Los Alamos, New Mexico
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The radio-frequency quadrupole (RFQ) accelerator is the best structure immediately after an ion source for accelerating light-ion beams with considerable currents. On the other hand, the higher-energy part of the RFQ is known to be not a very efficient accelerator. We consider alternative room-temperature RF accelerating structures for the beam velocities in the range of a few percent of the speed of light - including H-mode cavities and drift-tube linacs - and compare them with respect to their efficiency, compactness, ease of fabrication, and overall cost. Options for the beam transverse focusing in such structures are discussed. Possible applications include a compact deuteron-beam accelerator up to the energy of a few MeV for homeland defense.
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Slides
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| FRPMS051 |
Proposed Beam Diagnostics Instrumentation for the LANSCE Refurbishment Project
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4099 |
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- J. D. Gilpatrick, B. Blind, M. J. Borden, J. L. Erickson, M. S. Gulley, S. S. Kurennoy, R. C. McCrady, J. F. O'Hara, M. A. Oothoudt, C. Pillai, J. F. Power, L. Rybarcyk, F. E. Shelley
LANL, Los Alamos, New Mexico
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Funding: *Work supported by the U. S. Department of Energy.
Presently, the Los Alamos National Laboratory is in the process of planning a refurbishment of various sub-systems within its Los Alamos Neutron Science Center accelerator facility. A part of this LANSCE facility refurbishment will include some replacement of and improvement to existing older beam diagnostics instrumentation. While plans are still being discussed, some instrumentation that is under improvement or replacement consideration are beam phase and position measurements within the 805-MHz side-coupled cavity linac, slower wire profile measurements, typically known as wire scanners, and possibly additional installation of fast ionization-chamber loss monitors. This paper will briefly describe the requirements for these beam measurements, what we have done thus far to answer these requirements, and some of the technical issues related to the implementation of these instrumentation.
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| FRPMS053 |
Electromagnetic Modeling of Beam Position and Phase Monitors for LANSCE Linac
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4111 |
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- S. S. Kurennoy
LANL, Los Alamos, New Mexico
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Electromagnetic modeling has been used to compare pickup designs of the beam position and phase monitors (BPPM) for the Los Alamos Neutron Science Center (LANSCE) linac. This study is a part of the efforts to upgrade LANSCE beam diagnostics*. MAFIA 3-D time-domain simulations with an ultra-relativistic beam allow computing the signal amplitudes and phases on the BPPM electrodes for the given processing frequency, 402.5 MHz, as functions of the beam transverse position. An analytical model can be applied to extrapolate the simulation results to lower beam velocities. Based on modeling results, a BPPM design with 4 one-end-shorted electrodes each covering 60-degree subtended angle, similar to the SNS linac BPPM**, appears to provide the best combination of mechanical and diagnostics properties for the LANSCE side-coupled linac.
* J. D. Gilpatrick et al. These proceedings.** S. S. Kurennoy and R. E. Shafer, EPAC 2000 (Vienna, Austria, 2000), 1768.
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| FRPMS055 |
LANSCE Prototype Beam Position and Phase Monitor (BPPM) Mechanical Design
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4123 |
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- J. F. O'Hara, M. J. Borden, D. C. Bruhn, J. L. Erickson, J. D. Gilpatrick, S. S. Kurennoy
LANL, Los Alamos, New Mexico
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Funding: Work supported by United States Department of Energy
A prototype Beam Position and Phase Monitor (BPPM) beam line device is being designed to go in the LANSCE 805-MHz linac. The concept is to install two beam line devices in locations where their measurements can be compared with older existing Delta-T loop and wire scanner measurements. The plan is to install two devices so that transverse position, angular trajectory, as well as central beam phase and energy will be measured. The mechanical design will combine features from previous LANL designs that were done for the LANSCE Isotope Production Facility, LANSCE Switchyard project, and those done for the SNS linac. This paper will discuss the mechanical design and fabrication issues encountered during the course of developing the BPPM.
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