3. ACCELERATOR TECHNOLOGIES FOR PRESENT AND FUTURE ACCELERATOR FACILITIES

 

The development of improved accelerator technology is the foundation on which the Office of Basic Energy Sciences facilities are upgraded and new facilities built. 

 

Grant applications are sought only in the following subtopics:

 

 

a. Accelerator Modeling and Control—Grant applications are sought to develop new or improved computational tools for the design, study, or operation of charged particle beams.  Of particular interest is the development of a front-end design for user-friendly interfaces.  The modeling challenges addressed must be relevant to present and future BES accelerator facilities.  These challenges include, but are not limited to, beam halo generation and control; generation and synchronization of sub-ps x-ray pulses; wakefield computation; multiple and single bunch collective instabilities; electron cloud generation and effects, especially in high-intensity proton rings; and high-intensity operation (beam losses, thermal effects, etc.) 

Grant applications also are sought to investigate and develop enhancements to the suite of tools in the Experimental Physics and Industrial Control System (EPICS), in order to better support existing facilities and meet the requirements of future machines.  Areas of interest include, but are not limited to, high-availability alternative-communication protocols; enhanced functionality within the Input-Output Controller; highly integrated development environments; and ensuring scalability to very large installations (such as the International Linear Collider).  Grant applications should address how the results will guide long-term EPICS development.

Finally, as the time scale of interest in modern accelerators is reduced, the required computational resources are becoming prohibitive for currently-available low-order electromagnetic codes; for example, the estimated memory requirement for modeling a typical accelerator structure interacting with a 1-ps bunch is 1 TB.  Such an extreme computation is intractable for most accelerator laboratories.  Therefore, in order to break the computational bottleneck, grant applications are sought to develop computational electromagnetic codes with high-order accuracy.

 

Questions - contact Roger Klaffky (roger.klaffky@science.doe.gov)

 

 

b. Radio Frequency (RF) Devices and Components—With respect to high level RF accelerator systems, grant applications are sought to develop: 

 

(1) A high-level amplitude and phase modulator (in either waveguide or coaxial topology) that can demonstrate modulation ability out to 20 kHz.  Significant cost savings could be achieved if one klystron were used to drive multiple accelerating cavities, while retaining phase and amplitude control at the individual cavity level.

(2) A variable input coupler for normal conducting (NC) and superconducting (SC) RF cavities.  Approaches must demonstrate a significant increase in mechanical complexity compared with fixed coupler designs, and provide for adjustments of the input coupler beta in situ, in order to optimize the RF system efficiency.

(3) A high-efficiency-switching high-voltage power supply for next generation RF accelerator systems, which will need cleaner HV DC power on RF amplifier devices, in order to create less phase and amplitude jitter on the RF output.  Regulation of line power ripple must be achieved at the 0.5% level.

(4) Higher order mode (HOM) inductive output tube (IOT) continuous wave (CW) amplifiers at 350 MHz (tunable over a reasonable range would be desirable) at two power levels:  1 MW CW (applicable to the case where one amplifier drives several cavities) and 200 kW CW (in the case where each cavity has its own amplifier).  Such a device could provide lower operating voltage, smaller size, and lower operating cost (approximately 15-20% higher efficiency over current klystrons).  The potential energy cost savings with an IOT that could operate at ~70% efficiency (television IOTs approach that now with depressed collectors) would be significant.  Making the IOTs tunable over a reasonable range also would be a desirable feature.

(5) Pulsed inductive output tube (IOT) amplifier at 402.5 MHz, 140 kW, 10% duty factor for low-energy bunching application for high power H-/proton beams.

(6) A very high power (60-80 kW) solid state power amplifier to replace klystron amplifiers in synchrotron light sources.

(7) HOM damped superconducting RF cavities to be used as accelerating cavities at 500 MHz and/or as a bunch lengthening cavities at 1500 MHz.

(8) A 1KHz. 300 kV, 300A solid-state modulator for production of pico-second X-ray pulses using RF deflecting cavities.

(9) Development of higher power Integrated Gate Bipolar Transistor (IGBT) technology.  IGBTs with > 6000Volts, >2000Amps are required for development of high power modulators and power supplies.

(10) Development of robust high average power (200kW) 1kHz modulator system.  System to operate at about 300 kV, 300 A with ultimate rep rate at 1kHz or higher.

(11) Development of a high power fundamental power coupler (FPC) for ERL injector cavities with the following specifications: 1408 MHz operating frequency, average RF power up to 200 kW in traveling waver (TW) mode, nominal external Q of 5 x 104, factor of 10 variable coupling with minimum transverse kick to the beam.

 

With respect to low level RF[LLRF] accelerator systems, grant applications are sought to develop: 

 

(1) An RF phase detector that can provide accurate measurements of phase jitter down to 0.01°, which is needed at several accelerator facilities (e.g., the Linear Coherent Light Source and for future ultra-short x-ray capabilities at the Advanced Photon Source) and can provide an independent accurate measurement of the LLRF control performance.  When the accelerator beam itself is used to determine RF system performance, facility commissioning is difficult.

(2) A user-friendly, multi-channel "all in one" time-stamp diagnostic instrument that can accept base-band RF signals out to 3 GHz, as well as DC signals, for analysis of RF accelerator system fault events.  Accurate and timely fault analysis is necessary for present and future user facilities to operate at a very high level of reliability, and an "all-in-one" box would be more efficient than using several individual scopes.

 

Grant applications also are sought to develop devices for the manipulation of electron beams in storage rings and linear accelerators.  Such devices are used to facilitate deflection of the beam onto a predicted trajectory or to generate a time-space correlation in the beam.  For example, electromagnetic (RF) cavities operating in a dipole mode could introduce a transverse kick to an electron bunch as a whole or provide a “head-tail” displacement within the bunch.  Such cavities would need to provide deflecting kick voltages up 10 MV, with phase error < 0.01° and amplitude error <10-4, with parasitic modes damped to Q-values <1000 and with minimal short-range wakefields.

 

Finally, grant applications are sought to develop new or improved acceleration schemes for linac-driven synchrotron radiation sources.  Designs should provide high gradient (10-100 MVm-1) in CW mode, with high efficiency wall-plug-to-beam-power conversion.  Systems should be capable of supporting up to 500 mA beam current, with parasitic mode Q-values below 1000, and with minimal short-range wakefields.

 

Questions - contact Roger Klaffky (roger.klaffky@science.doe.gov)

 

 

c. Superconducting Technology for Accelerators—Complete 476 MHz superconducting RF systems are needed for present and future storage ring applications.  Grant applications are sought to develop: 

 

(1) A single-cell 476 MHz superconducting RF cavity that can support 2A CW operation, provide more than 2 MW energy gain with field gradient excess of more than 10 MV/m, and have a loaded Q higher than 108 at 4.5 k.

(2) An RF power coupler capable of handling 500 kW cw RF power.

(3) Digital, low-level RF systems to control the phase and amplitude of superconducting RF cavities operating at 476 MHz, with loaded Q-values in the range of 108.  Of particular interest are systems capable of phase control at the level 2o or better, and amplitude control at the level of 1% or better.

 

In addition, with the successful implementation of superconducting radiofrequency accelerating structures at facilities in all regions of the world, additional emphasis is being placed on reducing superconducting radiofrequency (SRF) cryomodule costs and improving manufacturing quality.  Therefore, grant applications are sought for innovative concepts and design approaches to the manufacture of cryomodule assemblies containing multiple-processed SRF cavities.  Approaches of interest include new cavity cooling and support systems, reliable cavity tuners and tuner components, and less expensive fundamental couple assemblies.

Finally, a fundamental conceptual issue has arisen concerning the cooling of superconducting linacs during high-power pulsed operation.  At fast pulse (1 ms), high-average forward-power levels (~ 75 kW), excessive thermal radiation loads from the fundamental couplers result in high couple surface temperatures, which reduce cavity stability and operating accelerating gradients.  Therefore, grant applications are sought to develop innovative cooling concepts for fundamental power couplers, which do not impact the performance of the associated superconducting cavities.

 

Questions - contact Roger Klaffky (roger.klaffky@science.doe.gov)


d. Advanced Sources for Accelerators—Grant applications are sought to develop novel electron gun features including: 

 

(1) Robust materials suitable for production of low emittance electron bunches at high repetition rate using laser excitation.  Intrinsic normalized emittance of the electron beam must be of order 10-7 m-mrad, in bunches of order 100 pC charge, duration of approximately 10 ps, and with quantum efficiency of 10-2 or greater.  Materials should be robust to environmental conditions, have small dark current under applied electric fields of order 10-100 MVm-1, and have long lifetime.

(2) High power laser oscillator systems for high repetition rate (1-100 MHz) electron guns that can deliver pulses of 10-100 µJ energy in the 1 µm wavelength range, with pulses capable of being expanded to10-50 ps duration.

(3) Accelerating structures supporting electric fields of 10-100 MVm-1 at a cathode surface, allowing laser excitation of the cathode material and rapid acceleration of the emitted electrons with minimal emittance growth, and having an electron bunch repetition rate of 1 MHz or greater.  Combined with suitable cathode materials and a photocathode laser, the system should be capable of producing low emittance (less than 1 mm-mrad normalized) electron bunches at a minimum 1 MHz repetition rate, with up to 1 nC charge per bunch.

 

In addition, grant applications are sought to develop high-current, high brightness sources of negative hydrogen ions.  The goal is the production of ~70 mA of H- with a normalized emittance of 0.2 ×pmm×mrad, or about 100 mA, with a normalized emittance of 0.35 ×pmm×mrad. These currents and emittances have to be achieved for 1 ms long pulses at 60 Hz.  The current should remain constant within ~5%.  The lifetime as well as the mean-time-between-failure should exceed several weeks.  Of special interests are highly efficient ionization technologies that can produce such beams with moderate power levels (< 40 kW peak power).

Finally, advanced undulator radiation sources are required for current and future light sources. 

 

Grant applications are sought for the development of: 

 

(1) Superconducting undulators (SCUs) that can generate tunable, monochromatic x-ray beams in the 2-30 keV photon energy range from medium-energy (2-3 GeV) synchrotrons.  These requirements demand that the undulators have a short period (around 1.5 cm) and high peak magnetic fields (around 1.6 tesla).  The permanent-magnets commonly used in undulators do not produce sufficiently high magnetic fields to fully cover the desired photon energy range without gaps in the spectrum.  Development efforts are underway at several National Laboratories and in industry to develop SCUs that promise to overcome these deficiencies.  However, current designs suffer from an inability to operate without quenching in the presence of the heat induced by the stored electron beam current and by synchrotron radiation encountered in modern synchrotron light sources.  This heat load can be up to 100 watts per meter of undulator length.  Novel ideas for SCU design, construction, and thermal management are needed to meet these challenging requirements.

(2) Undulators with period < 1 cm.  The resonant condition for undulator radiation at short wavelength (approximately 1 nm), with low energy electron beams (of 1-2 GeV), requires undulators with period that is shorter than generally available on existing synchrotron radiation sources.  Undulator designs are sought with K-value ~1, impedance shielding of pole faces, and a gap of greater than 2.25 mm.

 

Questions - contact Roger Klaffky (roger.klaffky@science.doe.gov)

 

Subtopic a References:

 

1        Bisognano, J. J. and Mondelli, A. A., eds., Computational Accelerator Physics, Williamsburg, VA, September 24-27, 1996, American Institute of Physics (AIP), May 1997.  (AIP Conference Proceedings No. 391) (ISBN:  1-56396-671-9)

 

2        Qiang, J. and Ryne, R., “Parallel Beam Dynamics Simulation of Linear Accelerators,” Proceedings of ACES 2002:  18th Annual Review of Progress in Applied Computational Electromagnetics, Monterey, CA, March 18-22, 2002, January 31, 2002.  (Report No. LBNL-49550) (Full text available at:  http://www.osti.gov/energycitations/servlets/purl/792968-2qDC1P/native/792968.pdf)

 

3        Ko, K., “High Performance Computing in Accelerator Physics,” Proceedings of 18th Annual Review of Progress in Applied Computational Electromagnetics:  ACES-2002, Monterey, CA, March 18-22, 2002.  (Full text available at:  http://www-group.slac.stanford.edu/acd/Computers2.html#)

 

4        Ryne R., et al., “SciDAC Advances and Applications in Computational Beam Dynamics,” presented at SciDAC (Scientific Discovery Through Advanced Computing) 2005, San Francisco, June 26-30, 2005.  (Full text available at:  http://seesar.lbl.gov/anag/publications/colella/LBNL-58243.pdf)

 

5        Proceedings of ICAP 2004--the International Computational Accelerator Physics Conference:  St. Petersburg, Russia, June 2004, “Nuclear Instruments and Methods in Physics Research Section A:  Accelerators, Spectrometers, Detectors and Associated Equipment,” 58(1), March 2006.  (Abstracts and ordering information for papers available at:  http://sciencedirect.com.  One menu at left, Browse by journal title, above; then by volume and issue.)

 

6        Proceedings of EPICS (Experimental Physics and Industrial Control System) Collaboration Meeting, Argonne, IL, June 2006.  (Presentation slides available at:  http://www.aps.anl.gov/News/Conferences/2006/EPICS/index.html.  On menu at left click on “Presentations.”  To view slides, click on titles.)

 

 

Subtopic b References:

 

1.   Proceedings of Fourth CW and High Average Power RF Workshop, Argonne National Laboratory, Argonne, IL, May 1-4, 2006 .  (Abstracts and presentation slides available at:  (http://www.aps.anl.gov/News/Conferences/2006/CWHAP06/index.html)

 

2.   Proceedings of Low Level RF (Radio Frequency) Workshop, CERN, October 2005. (Abstracts and presentation slides available at:  http://ab-ws-llrf05.web.cern.ch/ab-ws-llrf05/.  On menu at left, click on “Conference programme and registration” and then on author index.  Click on titles next to authors’ names to view abstracts.  For slides, click on “slides”.)

 

3.   Kneisel, P., “Latest Developments in Superconducting RF Structures for Beta=1 Particle Acceleration,” Proceedings of EPAC06, (European Particle Accelerator Conference), Edinburgh, June 2006.  (Full text available at:  http://accelconf.web.cern.ch/AccelConf/e06/Pre-Press/WEXPA01.pdf)

 

4.   Hosoyama K., et al., “Crab Cavity Development,” (Full text available at:  http://www.lns.cornell.edu/public/SRF2005/pdfs/ThA09.pdf)

 

 

Subtopic c References:

 

1.      Schneider, W. J., et al., “Design of the SNS Cryomodule,” Proceedings of the 2001 Particle Accelerator Conference, Chicago, IL, June 2001.  (Full text available at:  http://www.jlab.org/.  On menu at left click on “Publications.”  Click on “Research Publications Submission and Search Database.”  Search by article title.)

 

2.      Campisi, I. E., “State of the Art Power Couplers for Superconducting RF Cavities,” EPAC 2002, Paris, June 2002.  (Full text available at:  http://accelconf.web.cern.ch/AccelConf/e02/TALKS/TUXGB002.pdf)

 

3.      Stirbet, M., et al., “High Power RF Tests on Fundamental Power Couplers for the SNS Project,” EPAC 2002, Paris, June 2002.  (Full text available at:  http://accelconf.web.cern.ch/AccelConf/e02/PAPERS/THPDO016.pdf)

 

4.      Padamsee, H., et al., “RF Superconductivity for Accelerators,” New York, Wiley & Sons, 1998.  (ISBN:  0471154326)

 

5.      “PEP II Cavities for the SPEAR 3 Upgrade,” ACCEL Instruments GmbH Website.  (URL:  http://www.accel.de/pages/pep2_cavities_for_spear3.html) 



Subtopic d References:

 

1.      Ben-Zvi, I. , “Ampere Average Current Photoinjector and Energy Recovery Linac,” presented at FEL 2004, Trieste, Italy, Aug. 29- Sept. 4, 2004.  (Full text available at:  http://accelconf.web.cern.ch/AccelConf/f04/.  Search by author.)

 

2.      Proceedings of the Future Light Source Workshop (FLS2006), Hamburg, Germany, May 2006.  (Full text available at:  http://adweb.desy.de/mpy/FLS2006/proceedings/index.htm)

 

3.      Stockli, M., “The Development of High-Current and High Duty-Factor H- Injectors,” presented at LINAC’06, Knoxville, TN, August 2006.  (Available from author by email request.  Email:  stockli@ornl.gov)

 

4.      Casalbuoni, S., et al., “Generation of X-Ray Radiation in a Storage Ring by a Superconductive Cold-Bore In-Vacuum Undulator,” Physical Review Special Topics:   Accelerators and Beams, 9(1), January 2006.  (ISSN:  1098-4402) (Full text available at:  http://prst-ab.aps.org/onecol/PRSTAB/v9/i1/e010702)

 

5.      Bernhard, A., et al., “Planar and Planar Helical Superconductive Undulators for Storage Rings:  State of the Art,” Proceedings of EPAC 2004, Lucerne, Switzerland, July 2004.  (Full text available at:  http://accelconf.web.cern.ch/AccelConf/e04/PAPERS/MOPKF025.PDF)

 

6.      T. Hara et al., “Cryogenic Permanent Magnet Undulators,” Physical Review Special Topics:  Accelerators and Beams, 7(5), May 2004.  (ISSN:  1098-4402) (Full text available at:  http://prst-ab.aps.org/pdf/PRSTAB/v7/i5/e050702)