15. ACCELERATOR
TECHNOLOGIES FOR PRESENT AND FUTURE ACCELERATOR FACILITIES
The Office of Basic
Energy Sciences, within the DOE’s Office of Science, is responsible for
current and future user facilities including the Spallation Neutron Source
(SNS), the Linear Coherent Light Source (LCLS), and the National Synchrotron
Light Source II (NSLSII). This topic
seeks the development of technology to enhance the operation of current
facilities and to provide for optimal performance of the new facilities.
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 specifically 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 Basic Energy Sciences
accelerator facilities, including, but 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
Experimental Physics and Industrial Control System (EPICS) suite of tools, in
order to better support existing facilities and meet the requirements of future
machines. Topics 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 the 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 requirements 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)
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,
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,
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
to create less phase and amplitude jitter on the RF output – regulation of
line power ripple must be achieved at the 0.5% level; and (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 would be a desirable feature also.
With respect to low level RF 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°
(needed at several accelerator facilities, e.g. the LCLS and future ultra-short
x-ray capabilities at APS) and an independent accurate measurement of the result
of LLRF control (when the accelerator beam itself is used to determine RF system
performance, facility commissioning is difficult); and (2) a user-friendly,
multi-channel "all in one" time-stamp diagnostic instrument that can
accept baseband 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 of 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)
Subtopic b
References:
1.
Proceedings of Fourth CW and High Average Power RF Workshop,
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)
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)
a RF power coupler capable of handling 500 kW cw RF power; and (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)
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,
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)
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 delivering pulses of 10-100 µJ energy in the 1 µm
wavelength range, with pulses capable of being expanded to10-50 ps duration; and
(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
with electron bunch repetition rate of 1 MHz or greater. Combined
with suitable cathode materials and photocathode laser system, the system should
be capable of producing low emittance (less than 1 mm-mrad normalized) electron
bunches at a minimum 1 MHz repetition rate, and 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 p×mm×mrad
or about 100 mA with a normalized emittance of 0.35 p×mm×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 to generate tunable, monochromatic x-ray
beams in the 2 - 30 keV photon energy range from medium-energy (2 - 3 GeV)
synchrotrons. This requires
undulators with short period (around 1.5 cm) and high peak magnetic fields
(around 1.6 tesla). 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
SCU's which promise to meet these requirements. However,
current designs suffer from 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 of SCU design, construction and thermal management 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 shorter than generally available on existing synchrotron radiation
sources. Undulator designs with
K-value ~1, impedance shielding of pole faces, and gap of greater than 2.25 mm.
Questions - contact Roger Klaffky (roger.klaffky@science.doe.gov)
Subtopic d References:
1.
Ben-Zvi,
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)
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