32. RADIO FREQUENCY ACCELERATOR TECHNOLOGY FOR HIGH ENERGY ACCELERATORS AND COLLIDERS
The DOE High Energy Physics (HEP) program supports a broad research and development (R&D) effort in the science, engineering, and technology of charged particle accelerators, storage rings, and associated apparatus. Advanced R&D is needed in support of this research in: (1) high gradient accelerator structures, (2) high peak power radio frequency (RF) technologies, and (3) new concepts for low-cost, very efficient, pulse power modulators. Relevance to applications in HEP must be explicitly described. RF accelerator R&D more appropriate to applications in nuclear physics is specifically excluded from this topic and should be submitted under Topic 27. Grant applications are sought only in the following subtopics:
a. Radio Frequency Acceleration Structures—Grant applications are sought for research on very high gradient RF accelerating structures, normal or superconducting, for use in accelerators and storage rings. Gradients >150 MV/m for electrons and >10 MV/m for protons in normal cavities are of particular interest, as are means for suppressing unwanted higher-order modes and reducing costs. In muon accelerator R&D, structures for capture and acceleration of large emittance muon beams and techniques for achieving gradients of 5-20 MV/m in cavities with frequencies between 5 and 400 MHz (including superconducting cavities whose resonant frequencies can be rapidly modulated) are of interest. Methods for reducing surface breakdown and multipactoring (such as spark-resistant materials or surface coatings, or special geometries) and for suppressing unwanted higher order modes also are of interest, as are studies of surface breakdown and its dependence on magnetic field. Grant applications should be applicable to devices operating at frequencies from 1 to 40 GHz, or between 5 and 400 MHz for muon accelerators.
Grant applications are also sought to develop simulation tools for modeling high-gradient structures, in order to predict such experimental phenomena as the onset of breakdown, post breakdown phenomena, and the damage threshold. Specific areas of interest include the modeling of: (1) surface emission, (2) material heating due to electron and ion bombardment, (3) multipactoring, and (4) ionization of atomic and molecular species. Approaches that include an ability to import/export CAD descriptions, a friendly graphical user interface, and good data visualization will be a plus.
Questions - contact LK Len (lk.len@science.doe.gov)
b. Radio Frequency Power for Linear Accelerators—Grant applications are sought to develop new concepts, high-power RF components, and instrumentation for use in producing high peak power in narrow-band, low-duty-cycle, and low-pulse-repetition-frequency (approximately 0.1 to 1 kHz) pulsed RF amplifiers. The principal application will be for future large multi-TeV electron/positron linear colliders. Of particular interest are innovations related to cost saving, manufacturability, and electrical efficiency. Also of interest are RF sources for high-gradient accelerator research.
Grant applications are sought for the development of RF sources at K- to Ka-band, with a power level of ~50 MW, a pulse width of ~1 µs, and a repetition rate of 100 Hz. The frequency stability and output spectrum must be suitable for driving a linac. Innovations that allow the source to be configured for different frequencies at low cost are of particular interest. In addition, grant applications are sought to develop electron beam sources, such as sheet or elliptical beams, relevant to the abovementioned high power RF applications.
The next generation of multi-TeV linear colliders will require many RF power handling components which are not presently available, e.g., RF windows, couplers, mode transformers, RF loads, and high power rings capable of operating at high pulse powers. Consequently, grant applications are sought to develop active or passive RF pulse compression systems capable of handling peak powers of 150-200 MW and 100-200-nanosecond pulsewidth at 30 GHz. Grant applications are also sought for passive and active RF components such as over-moded mode converters (e.g., rectangular to circular waveguide and vice versa), high-power RF windows, circulators, isolators, switches, and quasi-optical components.
Lastly, grant applications are sought for new concepts, approaches, or designs for radio-frequency amplifiers, or pulse compression schemes, for use in the acceleration and ionization cooling channels of a future muon collider. The amplifiers or compressors must have high peak power (>30 MW) and pulsed, low frequency (from 2 ms pulses at 20 MHz to 0.1 ms pulses at 200 MHz). Higher power (>100 MW) pulsed sources at higher frequencies, e.g., 30 µs at 400 MHz, also are of interest. All muon collider amplifiers must have moderate repetition rate capability (e.g., 15 Hz). Grant applications should address the cost per unit of peak power, including the cost of required power supplies.
Questions - contact LK Len (lk.len@science.doe.gov)
c. New Concepts or Components for Pulsed Power Modulators and Energy Storage—Most RF power sources for future linear colliders require high peak-power pulse modulators of considerably higher efficiency than presently available. Grant applications are sought for new types of modulators in the 400 kV – 1 MV range for driving currents of 200 - 800 A, with pulse lengths of 0.2 – 5.0 µs, and with rise- and fall-times less than 0.5 µs. Grant applications also are sought for the development of modulators with improved voltage control for RF phase stability in some alternate RF power systems, as well as cathode modulators that are compact and cost competitive compared to present cathode pulse modulator schemes. Grant applications should address issues related to cost saving, manufacturability, and electrical efficiency in modulators.
Grant applications are also sought to develop improved high power solid-state switches for pulse power switching. For some applications, requirements will include the ability to switch high current pulses (2-5 kA) at voltage levels of 2 to 6 kV with switching times less than 300 nsec. These switches must handle very high di/dt (20 kA/µs) at low duty cycle (<0.1%).
Existing Insulated Gate Bipolar Transistor (IGBT) packages for high voltage and high pulsed current (e.g. V > 3.3kV, I > 3 kA peak, 59 A average) are not optimized for very high speed pulsed power applications (6.6 MW peak for 3.2 µs at 120 Hz) due to failure modes induced by very rapid fall times (di/dt >10 kA/µs) and/or rise times (dV/dt >15 kV/µs) upon device turn-off. Therefore, grant applications are sought to reduce these failure modes through improved packaging of commercial IGBT chips, by incorporating appropriate protective circuitry in a high voltage power package designed specifically for high-speed transients.
Lastly, grant applications are sought to develop and optimize high reliability, high-energy-density energy storage capacitors for future solid state pulse power systems. The capacitors must: (1) deliver high peak pulse current (5 - 8 kA) in the partial discharge region (less than 10 percent voltage droop during pulse); (2) be designed with very low inductance connections to allow fast rise and fall time discharge without ringing (di/dt ~ 20 kA/µs); and (3) be packaged to meet the requirements of high power solid state board layouts and have minimum production cost.
Questions - contact LK Len (lk.len@science.doe.gov)
1. Abe, D. K. and Nusinovich, G. S., eds., “High Energy Density and High Power RF: 7th Workshop on High Density and High Power RF,” Kalamata, Greece, June 13-17, 2005, New York: American Institute of Physics (AIP), 2006. (AIP Conference Proceedings No. 807) (ISBN: 0-7354-0298-1)*
2. Cline, D. B., ed., “Muon Collider Studies,” Physics Potential and Development of μ++-μ-- Colliders, Fourth International Conference, San Francisco, CA, December 1997, pp. 183-344, American Institute of Physics, 1998. (AIP Conference Proceedings No. 441) (ISBN: 1-56396-723-5)*
3. “Advanced Accelerator Concepts, 12th Workshop,” Lake Geneva, WI, July 10-15, 2006, U.S. DOE Argonne National Laboratory Website. (URL: http://www.hep.anl.gov/aac06/)
4. Yakimenko, V., ed, “Advanced Accelerator Concepts, 11th Workshop,” Stony Brook, New York, June 21-26, 2004, New York: American Institute of Physics, 2004. (AIP Conference Proceedings No. 737) (ISBN: 0-7354-0220-5)*
5. “Twenty-Second International Linear Accelerator Conference, LINAC 2004,” Lubeck, Germany, August 16-20, 2004, Website. (URL: http://www.linac2004.de/)
6. Kirkici, H., ed., “Proceedings of the 26th International Power Modulator Symposium and 2004 High Voltage Workshop,” San Francisco, CA, May 23-26, 2004. (IEEE Catalog Number: 04CH37588) (ISBN: 0-7803-8586-1)
7. Duggan, J. L. and Morgan, I. L., eds., “Application of Accelerators in Research and Industry: Seventeenth International Conference on the Application of Accelerators in Research and Industry,” Denton, TX, November 12-13, 2002, New York: American Institute of Physics, August 2003. (AIP Conference Proceedings No. 680) (ISBN: 0-7354-0149-7)*
8. King, B., ed., “Colliders and Collider Physics at the Highest Energies: Muon Colliders at 10 TeV to 100 TeV: HEMC '99 Workshop,” Montauk, NY, Sept. 27- Oct. 1, 1999, New York: American Institute of Physics, 2000. (AIP Conference Proceedings No. 530) (ISBN: 1-56396-953-X)*
9. Horak, C., ed., “Proceedings of the 2005 Particle Accelerator Conference,” Knoxville, TN, May 16-20, 2005, Institute of Electrical and Electronics Engineers (IEEE), 2005. (IEEE Catalog: 05CH37623C) (ISBN: 0-7803-8860-7);
10. “Eighth International Workshop on Neutrino Factories, Superbeams and Betabeams, NuFact 06,” Irvine, CA, August 24-30, 2006 Website. (URL: http://nufact06.physics.uci.edu/)
11. Para, A., ed., “Neutrino Factories and Superbeams: 5th International Workshop on Neutrino Factories and Superbeams NuFact 03,” New York, NY, June, 5-11, 2003. New York: American Institute of Physics, October 2004. (AIP Conference Proceedings No. 721) (ISBN: 0-7354-0201-9)*
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* Abstracts and ordering information available at: http://proceedings.aip.org/proceedings/
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