2011 Particle Accelerator Conference - List of Keywords (extraction)

Paper	Title	Other Keywords	Page
MOP059	Simulations of the Tapered Guggenheim 6d Cooling Channel for the Muon Collider	emittance, simulation, lattice, collider	217
	P. Snopok IIT, Chicago, Illinois, USA G.G. Hanson UCR, Riverside, California, USA R. B. Palmer BNL, Upton, Long Island, New York, USA
	Funding: Work is supported by the U.S. Department of Energy. Recent progress in six-dimensional (6D) cooling simulations for the Muon Collider based on the RFOFO ring layout is presented. In order to improve the performance of the cooling channel a tapering scheme is studied that implies changing the parameters such as cell length, magnetic field strength, RF frequency, and the amount of the absorbing material along the cooling channel. This approach allows us to keep the cooling rates high throughout the process. The results of the simulations carried out in G4beamline are presented.

MOP130	New Studies of X-band Dielectric-loaded Accelerating Structures	multipactoring, electron, plasma, cavity	337
	S.H. Gold NRL, Washington, DC, USA S.P. Antipov, W. Gai, C.-J. Jing, R. Konecny, J.G. Power ANL, Argonne, USA A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA A.K. Kinkead Icarus Research, Inc., Bethesda, Maryland, USA
	Funding: Work supported by the DoE Office of High Energy Physics and ONR. A joint program is under way to study externally driven X-band dielectric-loaded accelerating (DLA) structures and CLIC-type power extraction structures. The structures are designed and fabricated by Argonne National Laboratory and Euclid Techlabs and tested at up to 20 MW drive power using the X-band Magnicon Facility at the Naval Research Laboratory, with additional tests carried out at SLAC. Thus far, tests have been carried out on a large variety of structures fabricated from quartz, alumina, and MCT-20, and the principal problems have been multipactor loading and rf breakdown.* Multipactor loading occurs on the inner surface of the dielectric in a region of strong normal and tangential rf electric fields; rf breakdown occurs principally at discontinuities in the dielectric. Gap-free DLA structures have been tested at 15 MV/m without breakdown. New tests are being prepared to address these two issues. New gap-free structures will make use of a metallic coating on the outer surface of the dielectric in order to permit tapering both the inner and outer diameters for rf matching, while new multipactor studies will examine the use of grooved surfaces to suppress multipactor. * C. Jing, W. Gai, J.G. Power, R. Konecny, W. Liu, S.H. Gold, A.K. Kinkead, S.G. Tantawi, V. Dolgashev, and A. Kanareykin, IEEE Trans. Plasma Sci., vol. 38, pp. 1354–1360, June 2010.

MOP174	The Study and Implementation of Signal Processing Algorithm for Digital Beam Position Monitor	storage-ring, brilliance, betatron, injection	414
	L.W. Lai, Z.C. Chen, Y.B. Leng, Y.B. Yan, G.S. Yang SSRF, Shanghai, People's Republic of China X. Yi SINAP, Shanghai, People's Republic of China
	Digital beam position monitor (DBPM) system is one of the most important beam diagnostic instruments generally used in modern accelerators. The performance of DBPM is mainly given by its digital signal processing algorithm. In order to find out a better solution for our new DBPM system, two algorithms have been designed and implemented on a commercial FPGA based DAQ module (ICS1554) to retrieve the turn-by-turn (TBT) data. The first algorithm is based on frequency mixing, and the second one on discrete Fourier transform (DFT). Laboratory tests show that the standard deviation of measured positions can be better than 1μm at 5 dBm with input signal stronger than 5 dBm for both algorithms. And on-line evaluation indicates that real beam motion can be observed correctly using either algorithm.

MOP265	The FONT5 Prototype ILC Intra-train Feedback System at ATF2	feedback, kicker, linear-collider, simulation	600
	P. Burrows, R. Apsimon, D.R. Bett, G.B. Christian, B. Constance, C. Perry, J. Resta-López JAI, Oxford, United Kingdom
	We present the design and beam test results of a prototype beam-based digital feedback system for the Interaction Point of the International Linear Collider. A custom analogue front-end signal processor, FPGA-based digital signal processing boards, and kicker drive amplifier have been designed, built, deployed and tested with beam in the extraction line of the KEK Accelerator Test Facility (ATF2). The system was used to provide orbit correction in y and y' to the train of bunches extracted from the ATF damping ring. We describe the feedback performance in both single and coupled-loop modes and the optimisation of the loop gains.

TUODN3	Beam Dynamics Studies of Parallel-Bar Deflecting Cavities	cavity, simulation, emittance, electron	790
	S. Ahmed, J.R. Delayen, A.S. Hofler, G.A. Krafft, M. Spata, M.G. Tiefenback JLAB, Newport News, Virginia, USA K.B. Beard Muons, Inc, Batavia, USA K.A. Deitrick RPI, Troy, New York, USA S.D. Silva ODU, Norfolk, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and superconducting. The compact size of these cavities as compared to conventional TM₁₁₀ type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of eight 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and superconducting structures show very small emittance dilution due to the vertical kick of the beam.
	Slides TUODN3 [1.558 MB]

TUP058	Fundamental Damper Power Calculation of the 56MHz SRF Cavity for RHIC	cavity, simulation, SRF, insertion	919
	Q. Wu, S. Bellavia, I. Ben-Zvi, M.C. Grau, G. Miglionico, C. Pai BNL, Upton, Long Island, New York, USA
	Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. At each injection and extraction period of RHIC operation, the beam frequency will be sweeping across a wide range, and some of the harmonics will cross the frequency of the 56MHz SRF cavity. To avoid cavity excitation during these periods, a fundamental damper was designed for the quarter-wave resonator to heavily detune the cavity. The power extracted by the fundamental damper should be compliant with the cooling ability of the system at all stages. In this paper, we discussed the power output from the fundamental damper when it is fully extracted, inserted, and during its movement.

TUP166	Novel Quench Detection System For HTS Coils	target, power-supply, controls, background	1136
	P.N. Joshi, S. Dimaiuta, G. Ganetis, R.C. Gupta, Y. Shiroyanagi BNL, Upton, Long Island, New York, USA
	As a part of HTS magnet R&D, small coils are being built and tested to study quench properties in a systematic manner. Fot this purpose, multi-channel quench detection, fast and slow data logger, current ramp controller and energy extraction system was developed. This system had to be flexible, compact, economical and easy to use. The system is based on LabView and FPGA hardware from National Instrument.

TUP259	A Solid-State Nanosecond Beam Kicker Modulator Based on the DSRD Switch	kicker, high-voltage, status, impedance	1310
	A.L. Benwell, R. Akre, C. Burkhart, A. Krasnykh, T. Tang SLAC, Menlo Park, California, USA A. Kardo-Sysoev IOFFE, St. Petersburg, Russia
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 A fast solid-state beam kicker modulator is under development at the SLAC National Accelerator Laboratory. The program goal is to develop a modulator that will deliver 4 ns, ±5 kV pulses to the ATF2 damping ring beam extraction kicker. The kicker is a 50 Ω, bipolar strip line, 60 cm long, fed at the downstream end and terminated at the upstream end. The bunch spacing in the ring is 5.6 ns, bunches are removed from the back end of the train, and there is a gap of 10³.6 ns before the next train. The modulator design is based on an opening switch topology that uses Drift Step Recovery Diodes as the opening switches. The design and results of the modulator development are discussed.

TUP274	Oak Ridge National Laboratory Spallation Neutron Source Electrical Systems Availability and Improvements	kicker, injection, pulsed-power, site	1337
	R.I. Cutler, D.E. Anderson, W.E. Barnett, J.D. Hicks, J.J. Mize, J. Moss, K. Norris, V.V. Peplov, K.R. Rust, J. T. Weaver ORNL, Oak Ridge, Tennessee, USA
	Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS electrical systems have been operational for 4 years. System availability statistics and improvements are presented for ac electrical systems, dc and pulsed power supplies and klystron modulators

TUP282	The MICE Target	target, acceleration, injection, proton	1355
	P.J. Smith, C.N. Booth, P. Hodgson, E. Overton, M. Robinson Sheffield University, Sheffield, United Kingdom G.J. Barber, K.R. Long Imperial College of Science and Technology, Department of Physics, London, United Kingdom E.G. Capocci, J.S. Tarrant STFC/RAL, Chilton, Didcot, Oxon, United Kingdom B.J.A. Shepherd STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The MICE experiment uses a beam of low energy muons to test the feasibility of ionization cooling. This beam is derived parasitically from the ISIS accelerator at the Rutherford Appleton Laboratory. A target mechanism has been developed and deployed that rapidly inserts a small titanium target into the circulating proton beam immediately prior to extraction without undue disturbance of the primary ISIS beam. The first target drive was installed in ISIS during 2008 and operated successfully for over 100,000 pulses. A second upgraded design was installed in 2009 and after more than half a million actuations is still in operation. Further upgrades to the target design are now being tried in a separate test rig at the Rutherford Appleton Laboratory. The technical specifications for these upgraded designs are given and the motivations for the improvements are discussed. Additionally, further future improvements to the current design are discussed.

WEP092	Space Charge Effect of the High Intensity Proton Beam during the Resonance Extraction for the MU2E Experiment at Fermilab	space-charge, septum, sextupole, resonance	1645
	C.S. Park, J.F. Amundson, J.A. Johnstone, V.P. Nagaslaev, S.J. Werkema Fermilab, Batavia, USA
	The proposed Mu2e experiment to search for direct μ to e conversion at Fermilab plans slow, resonant extraction of a beam with 3× 10¹² protons from the Debuncher ring. Space charge of this high intensity beam is a critical factor, since it induces significant betatron tune spread and consequently affects resonance extraction processes, such as spill uniformity and beam losses. This study shows the multi-particle simulation results in the early stages of resonance extraction and spill uniformity in the presence of 2D and 3D space charge effects.

WEP114	Transverse Instability of the Antiproton Beam In the Recycler Ring	antiproton, emittance, damping, bunching	1698
	L.R. Prost, C.M. Bhat, A.V. Burov, J.L. Crisp, N. Eddy, M. Hu, A.V. Shemyakin Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The brightness of the antiproton beam in Fermilab’s 8 GeV Recycler ring is limited by a transverse instability. This instability has occurred during the extraction process to the Tevatron for large stacks of antiprotons even with dampers in operation. This paper describes observed features of the instability, introduces the threshold phase density to characterize the beam stability, and finds the results to be in agreement with a resistive wall instability model. Effective exclusion of the longitudinal tails from Landau damping by decreasing the depth of the RF potential well is observed to lower the threshold density by up to a factor of two.

WEP115	The FNAL Injector Upgrade	rfq, quadrupole, linac, DTL	1701
	C.-Y. Tan, D.S. Bollinger, K.L. Duel, J.R. Lackey, W. Pellico Fermilab, Batavia, USA
	The present FNAL linac H⁻ injector has been operational since the 1970s and consists of two magnetron H⁻ sources and a 750keV Cockcroft-Walton Accelerator. In the upgrade, both slit-type magnetron sources will be replaced with circular aperture sources, and the Cockcroft-Walton with a 200MHz RFQ. Operational experience at BNL (Brookhaven National Laboratory) has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.

WEP149	Beam Measurement by a Wall Gap Monitor in ALPHA	linac, dipole, electron, injection	1761
	T.H. Luo, P.D. McChesney, P.E. Sokol IUCF, Bloomington, Indiana, USA S.-Y. Lee IUCEEM, Bloomington, Indiana, USA
	In this report, we present our electron beam measurements with a wall gap monitor (WGM) in ALPHA injection and extraction beam lines. The WGM is first bench mark tested, and then installed in the ALPHA injection line to measure both the macro andμpulse of the injected beam and calibrate the beam current. By scanning the bending magnet before the WGM, and applying a demodulation signal processing scheme, we measured the tomography of the longitudinal phase space of the injected beam. We moved the WGM to extraction beam line and measured the properties of the extracted beam. By comparing the frequency spectrum of injected and extracted beam, we have confirmed the debunching performance of ALPHA.

WEP201	Status of NSLS-II Booster	booster, injection, dipole, septum	1864
	S.M. Gurov, A. Akimov, O. Anchugov, A.M. Batrakov, E.A. Bekhtenev, O.V. Belikov, P.B. Cheblakov, V.P. Cherepanov, A.D. Chernyakin, V.G. Cheskidov, I.N. Churkin, A.N. Dubrovin, A. Erokhin, K. Gorchakov, S.E. Karnaev, G.V. Karpov, V.A. Kiselev, V.V. Kobets, V.V. Kolmogorov, V.M. Konstantinov, A.A. Korepanov, E.A. Kuper, V. Kuzminykh, E.B. Levichev, V.R. Mamkin, A.S. Medvedko, O.I. Meshkov, N. Nefedov, V.V. Neyfeld, I.N. Okunev, M. Petrichenkov, V.V. Petrov, A. Polyansky, D.N. Pureskin, A. Rakhimov, S.I. Ruvinsky, T.V. Rybitskaya, L.M. Schegolev, A.V. Semenov, D.V. Senkov, S.S. Serednyakov, S.V. Shiyankov, D.A. Shvedov, S.V. Sinyatkin, V.V. Smaluk, A.V. Sukhanov, L. Tsukanova, A.V. Utkin, K. Yaminov BINP SB RAS, Novosibirsk, Russia J.H. DeLong, R.P. Fliller, G. Ganetis, H.-C. Hseuh, I. Pinayev, T.V. Shaftan, S.K. Sharma, O. Singh, Y. Tian, F.J. Willeke BNL, Upton, Long Island, New York, USA P.A.E. Elkiaer Danfysik A/S, Jyllinge, Denmark
	The National Synchrotron Light Source II is a third generation light source under construction at Brookhaven National Laboratory. The project includes a highly optimized 3 GeV electron storage ring, linac pre-injector and full-energy booster-synchrotron. Budker Institute of Nuclear Physics builds booster for NSLS-II. The booster should accelerate the electron beam continuously and reliably from minimal 170 MeV injection energy to maximal energy of 3.15 GeV and average beam current of 20 mA. The booster shall be capable of multi-bunch and single bunch operation. This paper summarizes the status of NSLS-II booster and the main designed parameters.

WEP231	TRIUMF Cyclotron Beam Quality Improvement	cyclotron, TRIUMF, emittance, beam-losses	1921
	I.V. Bylinskii, R.A. Baartman, F.W. Bach, J.F. Cessford, G. Dutto, Y.-N. Rao, L.W. Root, R. Ruegg TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	TRIUMF cyclotron for decades operated at 500 MeV. Recently, the two primary beamlines 1A and 2A, have been reconfigured for running at 480 MeV. The objective was to reduce beam losses caused by the electromagnetic stripping by 30%. The radiation losses reduction was confirmed with both online measurements and residual activation field mapping after 8 month of beam production. In order to improve stability of both primary beams, one of the harmonic coils was configured in Bz-mode to compensate for the beam split ratio fluctuations. Br-mode of this coil and two outer radius trim coils was utilized to correct the beam vertical position at extraction. Moreover, to make the beam spot position on the target stable and insensitive to any uncontrolled movement of the stripper foil due to heat distortion, the beamline front end optics was tuned to compensate the cyclotron's inherent dispersion. Details of these developments and improvements are discussed in the paper.

WEP232	A Multi Megawatt Ring Cyclotron to Search for CP Violation in the Neutrino Sector	cyclotron, injection, cavity, proton	1924
	L. Calabretta, M.M. Maggiore, D. Rifuggiato INFN/LNS, Catania, Italy A. Calanna CSFNSM, Catania, Italy L.A.C. Piazza INFN/LNL, Legnaro (PD), Italy
	A new approach to search for CP violation in the neutrino sector* is proposed by the experiment called DAEδALUS (Decay At rest Experiment for cp At Laboratory for Underground Science). DAEδALUS needs three sources of neutrino fluxes, each one located at 1.5, 8 and 20 km from the underground detector. Each source has to be supplied with a proton beam with power higher than 1, 2 and 5 MW respectively. Here we present the study for a Superconducting Ring Cyclotron able to accelerate the H²⁺ molecules and to deliver proton beam with maximum energy of 800 MeV and the required power. Although the average power for the first 2 sites are 1 and 2 MW, the 20% duty cycle, required by the experiment, has the consequence that the peak power should stay in the range 5-10 MW and a peak current of about 4.5 mA of H²⁺ is necessary. We present the parameters of the superconducting magnetic sector simulated by the code TOSCA, the isochronous magnetic field produced and the magnetic forces acting on the coils. Some evaluation on the feasibility of the ring cyclotron, the advantages and problems relates with acceleration of the H²⁺ molecules will be also presented. * J. Alonso et al., “Expression of Interest for a Novel Search for CP Violation in the Neutrino Sector: DAEδALUS”, Jun 2010. e-Print: arXiv:1006.0260

WEP234	Longitudinal Dynamics in the EMMA ns-FFAG	acceleration, induction, injection, resonance	1927
	J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom N. Bliss STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J.A. Clarke, N. Marks, B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the Science and Technology Facilities Council UK. Grant Number: ST/G004277/1 EMMA is the first non-scaling FFAG to be constructed, whose use of linear magnets means that the accelerating electron bunch rapidly crosses many resonances. We have modeled the capture and acceleration of bunches in the serpentine channel created by the radio-frequency cavities, and compare it to a proposed experiment in which induction cells allow slow acceleration. Two induction cores each providing ~20kV over 1.65 μs enable a number of resonance crossing experiments.

WEP237	The Oak Ridge Isochronous Cyclotron Refurbishment Project	ion, cyclotron, ISOL, vacuum	1930
	A.J. Mendez, J.B. Ball, D. Dowling, S.W. Mosko, B.A. Tatum ORNL, Oak Ridge, Tennessee, USA
	Funding: Managed by UT-Battelle, LLC for the U.S. Department of Energy under contract DE-AC05-00OR22725. The Oak Ridge Isochronous Cyclotron (ORIC) has been in operation for nearly fifty years at the Oak Ridge National Laboratory (ORNL). Presently, it serves as the driver accelerator for the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), where beams are produced using the Isotope Separation Online (ISOL) technique for post-acceleration by the HRIBF 25URC tandem accelerator. Operability and reliability of ORIC are critical issues for the success of HRIBF and have presented increasingly difficult operational challenges for the facility in recent years. Earlier this year, a trim coil failure rendered ORIC inoperable for several months. This presented HRIBF with the opportunity to undertake various repairs and maintenance upgrades aimed at restoring the full functionality of ORIC and improving the reliability to a level better than what had been typical over the previous decade. In this paper, we present details of these efforts, including the replacement of the entire trim coil set and measurements of their radial field profile. Comparison of measurements and operating tune parameters with setup code predictions will also be presented.

WEP270	A High Current Density Li+ Alumino-silicate Ion Source for Target Heating Experiments	ion, ion-source, space-charge, target	1981
	P.K. Roy, W.G. Greenway, J.W. Kwan, P.A. Seidl, W.L. Waldron LBNL, Berkeley, California, USA
	Funding: This work was performed under the auspices of the U.S Department of Energy by LLNL under contract DE AC52 07NA27344, and by LBNL under contract DE-AC02-05CH11231. The NDCX-II accelerator has been designed for target heating experiments in the warm dense matter regime. It will use a large diameter (≈ 10.9 cm) Li+ doped alumino-silicate source with a pulse duration of 0.5 μs, and beam current of ≈ 93 mA. Characterization of a prototype lithium alumino-silicate sources is presented. Using 6.35 mm diameter prototype emitters (coated and sintered on a ≈ 75% porous tungsten substrate), at a temperature of ≈1275° C, a space-charge limited Li+ beam current density of ≈ 1 mA/cm² was measured. At higher extraction voltage, the source is emission limited at around ≈ 1.5 mA/cm², weakly dependent on the applied voltage. The lifetime of the ion source is ≈ 50 hours while pulsing the extraction voltage at 2 to 3 times per minute. Measurements under these conditions show that the lifetime of the ion source does not depend only on beam current extraction, and lithium loss may be dominated by neutral loss or by evaporation. The thickness of the coating does not affect the emission density. It is inferred that pulsed heating, synchronized with the beam pulse rate may increase the life time of a source.

WEP273	Saddle RF Antenna H⁻ Ion Source Progress	plasma, ion, ion-source, gun	1987
	V.G. Dudnikov, R.P. Johnson Muons, Inc, Batavia, USA S. Murray, T.R. Pennisi, M. Santana, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA
	Funding: Supported in part by USDOE Contract DE-AC05-00OR22725 and STTR Grant DE-SC0002690 In this project we are developing an RF H⁻ surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with a small AlN test chamber and different antennasandmagneticfieldconfigurationsweretestedin the SNS ion source Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H⁻ beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma source (TPS) has been designed. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing.

THOCN6	Flux-coupled Cyclotron Stack: Optimization for Maximum Beam Power and Minimum Losses	cavity, coupling, injection, cyclotron	2113
	P.M. McIntyre, A. Sattarov Texas A&M University, College Station, Texas, USA
	Funding: This work was supported in part by the U.S. Department of Energy under Grant DE-FG02-06ER41405 A flux-coupled stack of isochronous cyclotrons has been proposed as a driver for Accelerator-Driven Subcritical Systems (ADSS) for thorium-cycle fission power. The issues that limit beam current and phase space brightness are evaluated, including space charge tune shift, synchro-betatron coupling, orbit separation at injection and extraction, RF propagation within the accelerator envelope, RF parasitic modes, and stability of electrostatic septum operation. A design is presented that offers good optimization of these criteria.
	Slides THOCN6 [5.266 MB]

THP003	High Power THz FEL Source Based on FFAG Betatron	FEL, electron, betatron, radiation	2142
	A.Y. Murokh RadiaBeam, Santa Monica, USA S. Reiche PSI, Villigen, Switzerland
	A novel source of high power sub-mm waves is proposed that combines two well-known technologies – a betatron induction FFAG accelerator and a free electron laser (FEL). The system is configured as an FEL oscillator: the electron beam circulates in bi-periodic FFAG lattice and the external optical resonator maintains beam-radiation overlap through multiple orbits. Initial analysis shows that FEL gain and very high extraction efficiency are possible with modest injected beam current. A simplified interaction model and preliminary analysis results are presented.

THP005	High Power Cyclotron Complex for Neutron Production	cyclotron, proton, acceleration, electron	2145
	Yu.G. Alenitsky, A.A. Glazov, G.A. Karamysheva, S.A. Kostromin, E. Samsonov JINR, Dubna, Moscow Region, Russia S.N. Dolya, L.M. Onischenko, S.B. Vorozhtsov, N.L. Zaplatin JINR/DLNP, Dubna, Moscow region, Russia
	Now the cyclotron seems as the most suitable accelerator for production of proton beams with energy up to Ep= 800 MeV and the power Pp=10 MW. There are some offers on creation of such complexes, all of them have common properties. A full cycle of acceleration consists of three stages: high-voltage injection with bunching of continuous beam, then preliminary acceleration in fore sectors cyclotron and acceleration up to the maximal energy 500-800 MeV in the ring cyclotron with six or more sectors. At the first stage of acceleration instead of high-voltage injection one can use the parallel work of two cyclotrons with injection in the subsequent cascade of a beam of the double intensity. In our department of New Accelerators the magnetic and high-frequency systems of a ring cyclotron on the energy 50 - 800 MeV (so-called “supercyclotron”) have been developed. A project of cyclotron injector with energy of protons about 10 MeV has been suggested as injector for Fasotron JINR LNP. It is offered to continue development of the project of cyclotron facility with energy of protons Ер ~ 800 MeV and average current of beam up to 10 mA.

THP105	Final Design of ILC RTML Extraction Line for Single Stage Bunch Compressor	sextupole, kicker, septum, damping	2321
	S. Seletskiy BNL, Upton, Long Island, New York, USA N. Solyak Fermilab, Batavia, USA
	The use of single stage bunch compressor (BC) in the International Linear Collider (ILC) [1] Damping Ring to the Main Linac beamline (RTML) requires new design for the extraction line (EL). The EL located downstream of the BC will be used for both an emergency abort dumping of the beam and the tune-up continuous train-by-train extraction. It must accept both compressed and uncompressed beam with energy spread of 3.54% and 0.15% respectively. In this paper we report the final design that allowed minimizing the length of such extraction line while offsetting the beam dumps from the main line by 5m distance required for acceptable radiation level in the service tunnel. Proposed extraction line can accommodate beams with different energy spreads at the same time providing the beam size suitable for the aluminum ball dump window.

THP186	Lattice Design for ERL Options at SLAC	linac, emittance, injection, lattice	2465
	Y. Nosochkov, Y. Cai, X. Huang, M.-H. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy under Contract number DE-AC02 76SF00515. SLAC is investigating long-range options for building a high performance light source machine while reusing the existing linac and PEP-II tunnels. One previously studied option is the PEP-X low emittance storage ring. The alternative option is based on a superconducting Energy Recovery Linac (ERL) and the PEP-X design. The ERL advantages are the low beam emittance, short bunch length and small energy spread leading to better qualities of the X-ray beams. Two ERL configurations differed by the location of the linac have been studied. Details of the lattice design and the results of beam transport simulations with the coherent synchrotron radiation effects are presented

THP192	Effect of Surface Roughness on the Emittance from GaAs Photocathode	electron, cathode, emittance, gun	2480
	S.S. Karkare, I.V. Bazarov Cornell University, Ithaca, New York, USA L. Cultrera, A. Iyer, X. Liu, W.J. Schaff CLASSE, Ithaca, New York, USA
	Funding: This work is supported by NSF under Grant No. DMR- 0807731 and DOE under Grant No. DE-SC0003965. The surface roughness of GaAs photocathodes used in the injector prototype for the ERL at Cornell University was measured and compared to that of the atomically polished GaAs crystal surface using the atomic force microscopy (AFM) technique. The results show at least an order of magnitude rise in the GaAs surface roughness after subjecting it to heat cleaning, prior to activation. An analytical model for photoemission that takes into account the effect of surface roughness has been developed. This model predicts emittance values close to the experimental observations, explains the experimentally observed variation of emittance with incident light wavelength and reconciles the discrepancies in experimental data.

Paper

Title

Other Keywords

Page

MOP059

Simulations of the Tapered Guggenheim 6d Cooling Channel for the Muon Collider

emittance, simulation, lattice, collider

217

P. Snopok
IIT, Chicago, Illinois, USA
G.G. Hanson
UCR, Riverside, California, USA
R. B. Palmer
BNL, Upton, Long Island, New York, USA

Funding: Work is supported by the U.S. Department of Energy.
Recent progress in six-dimensional (6D) cooling simulations for the Muon Collider based on the RFOFO ring layout is presented. In order to improve the performance of the cooling channel a tapering scheme is studied that implies changing the parameters such as cell length, magnetic field strength, RF frequency, and the amount of the absorbing material along the cooling channel. This approach allows us to keep the cooling rates high throughout the process. The results of the simulations carried out in G4beamline are presented.

MOP130

New Studies of X-band Dielectric-loaded Accelerating Structures

multipactoring, electron, plasma, cavity

337

S.H. Gold
NRL, Washington, DC, USA
S.P. Antipov, W. Gai, C.-J. Jing, R. Konecny, J.G. Power
ANL, Argonne, USA
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
A.K. Kinkead
Icarus Research, Inc., Bethesda, Maryland, USA

Funding: Work supported by the DoE Office of High Energy Physics and ONR.
A joint program is under way to study externally driven X-band dielectric-loaded accelerating (DLA) structures and CLIC-type power extraction structures. The structures are designed and fabricated by Argonne National Laboratory and Euclid Techlabs and tested at up to 20 MW drive power using the X-band Magnicon Facility at the Naval Research Laboratory, with additional tests carried out at SLAC. Thus far, tests have been carried out on a large variety of structures fabricated from quartz, alumina, and MCT-20, and the principal problems have been multipactor loading and rf breakdown.* Multipactor loading occurs on the inner surface of the dielectric in a region of strong normal and tangential rf electric fields; rf breakdown occurs principally at discontinuities in the dielectric. Gap-free DLA structures have been tested at 15 MV/m without breakdown. New tests are being prepared to address these two issues. New gap-free structures will make use of a metallic coating on the outer surface of the dielectric in order to permit tapering both the inner and outer diameters for rf matching, while new multipactor studies will examine the use of grooved surfaces to suppress multipactor.
* C. Jing, W. Gai, J.G. Power, R. Konecny, W. Liu, S.H. Gold, A.K. Kinkead, S.G. Tantawi, V. Dolgashev, and A. Kanareykin, IEEE Trans. Plasma Sci., vol. 38, pp. 1354–1360, June 2010.

MOP174

The Study and Implementation of Signal Processing Algorithm for Digital Beam Position Monitor

storage-ring, brilliance, betatron, injection

414

L.W. Lai, Z.C. Chen, Y.B. Leng, Y.B. Yan, G.S. Yang
SSRF, Shanghai, People's Republic of China
X. Yi
SINAP, Shanghai, People's Republic of China

Digital beam position monitor (DBPM) system is one of the most important beam diagnostic instruments generally used in modern accelerators. The performance of DBPM is mainly given by its digital signal processing algorithm. In order to find out a better solution for our new DBPM system, two algorithms have been designed and implemented on a commercial FPGA based DAQ module (ICS1554) to retrieve the turn-by-turn (TBT) data. The first algorithm is based on frequency mixing, and the second one on discrete Fourier transform (DFT). Laboratory tests show that the standard deviation of measured positions can be better than 1μm at 5 dBm with input signal stronger than 5 dBm for both algorithms. And on-line evaluation indicates that real beam motion can be observed correctly using either algorithm.

MOP265

The FONT5 Prototype ILC Intra-train Feedback System at ATF2

feedback, kicker, linear-collider, simulation

600

P. Burrows, R. Apsimon, D.R. Bett, G.B. Christian, B. Constance, C. Perry, J. Resta-López
JAI, Oxford, United Kingdom

We present the design and beam test results of a prototype beam-based digital feedback system for the Interaction Point of the International Linear Collider. A custom analogue front-end signal processor, FPGA-based digital signal processing boards, and kicker drive amplifier have been designed, built, deployed and tested with beam in the extraction line of the KEK Accelerator Test Facility (ATF2). The system was used to provide orbit correction in y and y' to the train of bunches extracted from the ATF damping ring. We describe the feedback performance in both single and coupled-loop modes and the optimisation of the loop gains.

TUODN3

Beam Dynamics Studies of Parallel-Bar Deflecting Cavities

cavity, simulation, emittance, electron

790

S. Ahmed, J.R. Delayen, A.S. Hofler, G.A. Krafft, M. Spata, M.G. Tiefenback
JLAB, Newport News, Virginia, USA
K.B. Beard
Muons, Inc, Batavia, USA
K.A. Deitrick
RPI, Troy, New York, USA
S.D. Silva
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and superconducting. The compact size of these cavities as compared to conventional TM₁₁₀ type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of eight 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and superconducting structures show very small emittance dilution due to the vertical kick of the beam.

Slides TUODN3 [1.558 MB]

TUP058

Fundamental Damper Power Calculation of the 56MHz SRF Cavity for RHIC

cavity, simulation, SRF, insertion

919

Q. Wu, S. Bellavia, I. Ben-Zvi, M.C. Grau, G. Miglionico, C. Pai
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
At each injection and extraction period of RHIC operation, the beam frequency will be sweeping across a wide range, and some of the harmonics will cross the frequency of the 56MHz SRF cavity. To avoid cavity excitation during these periods, a fundamental damper was designed for the quarter-wave resonator to heavily detune the cavity. The power extracted by the fundamental damper should be compliant with the cooling ability of the system at all stages. In this paper, we discussed the power output from the fundamental damper when it is fully extracted, inserted, and during its movement.

TUP166

Novel Quench Detection System For HTS Coils

target, power-supply, controls, background

1136

P.N. Joshi, S. Dimaiuta, G. Ganetis, R.C. Gupta, Y. Shiroyanagi
BNL, Upton, Long Island, New York, USA

As a part of HTS magnet R&D, small coils are being built and tested to study quench properties in a systematic manner. Fot this purpose, multi-channel quench detection, fast and slow data logger, current ramp controller and energy extraction system was developed. This system had to be flexible, compact, economical and easy to use. The system is based on LabView and FPGA hardware from National Instrument.

TUP259

A Solid-State Nanosecond Beam Kicker Modulator Based on the DSRD Switch

kicker, high-voltage, status, impedance

1310

A.L. Benwell, R. Akre, C. Burkhart, A. Krasnykh, T. Tang
SLAC, Menlo Park, California, USA
A. Kardo-Sysoev
IOFFE, St. Petersburg, Russia

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515
A fast solid-state beam kicker modulator is under development at the SLAC National Accelerator Laboratory. The program goal is to develop a modulator that will deliver 4 ns, ±5 kV pulses to the ATF2 damping ring beam extraction kicker. The kicker is a 50 Ω, bipolar strip line, 60 cm long, fed at the downstream end and terminated at the upstream end. The bunch spacing in the ring is 5.6 ns, bunches are removed from the back end of the train, and there is a gap of 10³.6 ns before the next train. The modulator design is based on an opening switch topology that uses Drift Step Recovery Diodes as the opening switches. The design and results of the modulator development are discussed.

TUP274

Oak Ridge National Laboratory Spallation Neutron Source Electrical Systems Availability and Improvements

kicker, injection, pulsed-power, site

1337

R.I. Cutler, D.E. Anderson, W.E. Barnett, J.D. Hicks, J.J. Mize, J. Moss, K. Norris, V.V. Peplov, K.R. Rust, J. T. Weaver
ORNL, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
SNS electrical systems have been operational for 4 years. System availability statistics and improvements are presented for ac electrical systems, dc and pulsed power supplies and klystron modulators

TUP282

The MICE Target

target, acceleration, injection, proton

1355

P.J. Smith, C.N. Booth, P. Hodgson, E. Overton, M. Robinson
Sheffield University, Sheffield, United Kingdom
G.J. Barber, K.R. Long
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
E.G. Capocci, J.S. Tarrant
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
B.J.A. Shepherd
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The MICE experiment uses a beam of low energy muons to test the feasibility of ionization cooling. This beam is derived parasitically from the ISIS accelerator at the Rutherford Appleton Laboratory. A target mechanism has been developed and deployed that rapidly inserts a small titanium target into the circulating proton beam immediately prior to extraction without undue disturbance of the primary ISIS beam. The first target drive was installed in ISIS during 2008 and operated successfully for over 100,000 pulses. A second upgraded design was installed in 2009 and after more than half a million actuations is still in operation. Further upgrades to the target design are now being tried in a separate test rig at the Rutherford Appleton Laboratory. The technical specifications for these upgraded designs are given and the motivations for the improvements are discussed. Additionally, further future improvements to the current design are discussed.

WEP092

Space Charge Effect of the High Intensity Proton Beam during the Resonance Extraction for the MU2E Experiment at Fermilab

space-charge, septum, sextupole, resonance

1645

C.S. Park, J.F. Amundson, J.A. Johnstone, V.P. Nagaslaev, S.J. Werkema
Fermilab, Batavia, USA

The proposed Mu2e experiment to search for direct μ to e conversion at Fermilab plans slow, resonant extraction of a beam with 3× 10¹² protons from the Debuncher ring. Space charge of this high intensity beam is a critical factor, since it induces significant betatron tune spread and consequently affects resonance extraction processes, such as spill uniformity and beam losses. This study shows the multi-particle simulation results in the early stages of resonance extraction and spill uniformity in the presence of 2D and 3D space charge effects.

WEP114

Transverse Instability of the Antiproton Beam In the Recycler Ring

antiproton, emittance, damping, bunching

1698

L.R. Prost, C.M. Bhat, A.V. Burov, J.L. Crisp, N. Eddy, M. Hu, A.V. Shemyakin
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The brightness of the antiproton beam in Fermilab’s 8 GeV Recycler ring is limited by a transverse instability. This instability has occurred during the extraction process to the Tevatron for large stacks of antiprotons even with dampers in operation. This paper describes observed features of the instability, introduces the threshold phase density to characterize the beam stability, and finds the results to be in agreement with a resistive wall instability model. Effective exclusion of the longitudinal tails from Landau damping by decreasing the depth of the RF potential well is observed to lower the threshold density by up to a factor of two.

WEP115

The FNAL Injector Upgrade

rfq, quadrupole, linac, DTL

1701

C.-Y. Tan, D.S. Bollinger, K.L. Duel, J.R. Lackey, W. Pellico
Fermilab, Batavia, USA

The present FNAL linac H⁻ injector has been operational since the 1970s and consists of two magnetron H⁻ sources and a 750keV Cockcroft-Walton Accelerator. In the upgrade, both slit-type magnetron sources will be replaced with circular aperture sources, and the Cockcroft-Walton with a 200MHz RFQ. Operational experience at BNL (Brookhaven National Laboratory) has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.

WEP149

Beam Measurement by a Wall Gap Monitor in ALPHA

linac, dipole, electron, injection

1761

T.H. Luo, P.D. McChesney, P.E. Sokol
IUCF, Bloomington, Indiana, USA
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

In this report, we present our electron beam measurements with a wall gap monitor (WGM) in ALPHA injection and extraction beam lines. The WGM is first bench mark tested, and then installed in the ALPHA injection line to measure both the macro andμpulse of the injected beam and calibrate the beam current. By scanning the bending magnet before the WGM, and applying a demodulation signal processing scheme, we measured the tomography of the longitudinal phase space of the injected beam. We moved the WGM to extraction beam line and measured the properties of the extracted beam. By comparing the frequency spectrum of injected and extracted beam, we have confirmed the debunching performance of ALPHA.

WEP201

Status of NSLS-II Booster

booster, injection, dipole, septum

1864

S.M. Gurov, A. Akimov, O. Anchugov, A.M. Batrakov, E.A. Bekhtenev, O.V. Belikov, P.B. Cheblakov, V.P. Cherepanov, A.D. Chernyakin, V.G. Cheskidov, I.N. Churkin, A.N. Dubrovin, A. Erokhin, K. Gorchakov, S.E. Karnaev, G.V. Karpov, V.A. Kiselev, V.V. Kobets, V.V. Kolmogorov, V.M. Konstantinov, A.A. Korepanov, E.A. Kuper, V. Kuzminykh, E.B. Levichev, V.R. Mamkin, A.S. Medvedko, O.I. Meshkov, N. Nefedov, V.V. Neyfeld, I.N. Okunev, M. Petrichenkov, V.V. Petrov, A. Polyansky, D.N. Pureskin, A. Rakhimov, S.I. Ruvinsky, T.V. Rybitskaya, L.M. Schegolev, A.V. Semenov, D.V. Senkov, S.S. Serednyakov, S.V. Shiyankov, D.A. Shvedov, S.V. Sinyatkin, V.V. Smaluk, A.V. Sukhanov, L. Tsukanova, A.V. Utkin, K. Yaminov
BINP SB RAS, Novosibirsk, Russia
J.H. DeLong, R.P. Fliller, G. Ganetis, H.-C. Hseuh, I. Pinayev, T.V. Shaftan, S.K. Sharma, O. Singh, Y. Tian, F.J. Willeke
BNL, Upton, Long Island, New York, USA
P.A.E. Elkiaer
Danfysik A/S, Jyllinge, Denmark

The National Synchrotron Light Source II is a third generation light source under construction at Brookhaven National Laboratory. The project includes a highly optimized 3 GeV electron storage ring, linac pre-injector and full-energy booster-synchrotron. Budker Institute of Nuclear Physics builds booster for NSLS-II. The booster should accelerate the electron beam continuously and reliably from minimal 170 MeV injection energy to maximal energy of 3.15 GeV and average beam current of 20 mA. The booster shall be capable of multi-bunch and single bunch operation. This paper summarizes the status of NSLS-II booster and the main designed parameters.

WEP231

TRIUMF Cyclotron Beam Quality Improvement

cyclotron, TRIUMF, emittance, beam-losses

1921

I.V. Bylinskii, R.A. Baartman, F.W. Bach, J.F. Cessford, G. Dutto, Y.-N. Rao, L.W. Root, R. Ruegg
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

TRIUMF cyclotron for decades operated at 500 MeV. Recently, the two primary beamlines 1A and 2A, have been reconfigured for running at 480 MeV. The objective was to reduce beam losses caused by the electromagnetic stripping by 30%. The radiation losses reduction was confirmed with both online measurements and residual activation field mapping after 8 month of beam production. In order to improve stability of both primary beams, one of the harmonic coils was configured in Bz-mode to compensate for the beam split ratio fluctuations. Br-mode of this coil and two outer radius trim coils was utilized to correct the beam vertical position at extraction. Moreover, to make the beam spot position on the target stable and insensitive to any uncontrolled movement of the stripper foil due to heat distortion, the beamline front end optics was tuned to compensate the cyclotron's inherent dispersion. Details of these developments and improvements are discussed in the paper.

WEP232

A Multi Megawatt Ring Cyclotron to Search for CP Violation in the Neutrino Sector

cyclotron, injection, cavity, proton

1924

L. Calabretta, M.M. Maggiore, D. Rifuggiato
INFN/LNS, Catania, Italy
A. Calanna
CSFNSM, Catania, Italy
L.A.C. Piazza
INFN/LNL, Legnaro (PD), Italy

A new approach to search for CP violation in the neutrino sector* is proposed by the experiment called DAEδALUS (Decay At rest Experiment for cp At Laboratory for Underground Science). DAEδALUS needs three sources of neutrino fluxes, each one located at 1.5, 8 and 20 km from the underground detector. Each source has to be supplied with a proton beam with power higher than 1, 2 and 5 MW respectively. Here we present the study for a Superconducting Ring Cyclotron able to accelerate the H²⁺ molecules and to deliver proton beam with maximum energy of 800 MeV and the required power. Although the average power for the first 2 sites are 1 and 2 MW, the 20% duty cycle, required by the experiment, has the consequence that the peak power should stay in the range 5-10 MW and a peak current of about 4.5 mA of H²⁺ is necessary. We present the parameters of the superconducting magnetic sector simulated by the code TOSCA, the isochronous magnetic field produced and the magnetic forces acting on the coils. Some evaluation on the feasibility of the ring cyclotron, the advantages and problems relates with acceleration of the H²⁺ molecules will be also presented.
* J. Alonso et al., “Expression of Interest for a Novel Search for CP Violation in the Neutrino Sector: DAEδALUS”, Jun 2010. e-Print: arXiv:1006.0260

WEP234

Longitudinal Dynamics in the EMMA ns-FFAG

acceleration, induction, injection, resonance

1927

J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
N. Bliss
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
J.A. Clarke, N. Marks, B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Work supported by the Science and Technology Facilities Council UK. Grant Number: ST/G004277/1
EMMA is the first non-scaling FFAG to be constructed, whose use of linear magnets means that the accelerating electron bunch rapidly crosses many resonances. We have modeled the capture and acceleration of bunches in the serpentine channel created by the radio-frequency cavities, and compare it to a proposed experiment in which induction cells allow slow acceleration. Two induction cores each providing ~20kV over 1.65 μs enable a number of resonance crossing experiments.

WEP237

The Oak Ridge Isochronous Cyclotron Refurbishment Project

ion, cyclotron, ISOL, vacuum

1930

A.J. Mendez, J.B. Ball, D. Dowling, S.W. Mosko, B.A. Tatum
ORNL, Oak Ridge, Tennessee, USA

Funding: Managed by UT-Battelle, LLC for the U.S. Department of Energy under contract DE-AC05-00OR22725.
The Oak Ridge Isochronous Cyclotron (ORIC) has been in operation for nearly fifty years at the Oak Ridge National Laboratory (ORNL). Presently, it serves as the driver accelerator for the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), where beams are produced using the Isotope Separation Online (ISOL) technique for post-acceleration by the HRIBF 25URC tandem accelerator. Operability and reliability of ORIC are critical issues for the success of HRIBF and have presented increasingly difficult operational challenges for the facility in recent years. Earlier this year, a trim coil failure rendered ORIC inoperable for several months. This presented HRIBF with the opportunity to undertake various repairs and maintenance upgrades aimed at restoring the full functionality of ORIC and improving the reliability to a level better than what had been typical over the previous decade. In this paper, we present details of these efforts, including the replacement of the entire trim coil set and measurements of their radial field profile. Comparison of measurements and operating tune parameters with setup code predictions will also be presented.

WEP270

A High Current Density Li+ Alumino-silicate Ion Source for Target Heating Experiments

ion, ion-source, space-charge, target

1981

P.K. Roy, W.G. Greenway, J.W. Kwan, P.A. Seidl, W.L. Waldron
LBNL, Berkeley, California, USA

Funding: This work was performed under the auspices of the U.S Department of Energy by LLNL under contract DE AC52 07NA27344, and by LBNL under contract DE-AC02-05CH11231.
The NDCX-II accelerator has been designed for target heating experiments in the warm dense matter regime. It will use a large diameter (≈ 10.9 cm) Li+ doped alumino-silicate source with a pulse duration of 0.5 μs, and beam current of ≈ 93 mA. Characterization of a prototype lithium alumino-silicate sources is presented. Using 6.35 mm diameter prototype emitters (coated and sintered on a ≈ 75% porous tungsten substrate), at a temperature of ≈1275° C, a space-charge limited Li+ beam current density of ≈ 1 mA/cm² was measured. At higher extraction voltage, the source is emission limited at around ≈ 1.5 mA/cm², weakly dependent on the applied voltage. The lifetime of the ion source is ≈ 50 hours while pulsing the extraction voltage at 2 to 3 times per minute. Measurements under these conditions show that the lifetime of the ion source does not depend only on beam current extraction, and lithium loss may be dominated by neutral loss or by evaporation. The thickness of the coating does not affect the emission density. It is inferred that pulsed heating, synchronized with the beam pulse rate may increase the life time of a source.

WEP273

Saddle RF Antenna H⁻ Ion Source Progress

plasma, ion, ion-source, gun

1987

V.G. Dudnikov, R.P. Johnson
Muons, Inc, Batavia, USA
S. Murray, T.R. Pennisi, M. Santana, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA

Funding: Supported in part by USDOE Contract DE-AC05-00OR22725 and STTR Grant DE-SC0002690
In this project we are developing an RF H⁻ surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with a small AlN test chamber and different antennasandmagneticfieldconfigurationsweretestedin the SNS ion source Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H⁻ beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma source (TPS) has been designed. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing.

THOCN6

Flux-coupled Cyclotron Stack: Optimization for Maximum Beam Power and Minimum Losses

cavity, coupling, injection, cyclotron

2113

P.M. McIntyre, A. Sattarov
Texas A&M University, College Station, Texas, USA

Funding: This work was supported in part by the U.S. Department of Energy under Grant DE-FG02-06ER41405
A flux-coupled stack of isochronous cyclotrons has been proposed as a driver for Accelerator-Driven Subcritical Systems (ADSS) for thorium-cycle fission power. The issues that limit beam current and phase space brightness are evaluated, including space charge tune shift, synchro-betatron coupling, orbit separation at injection and extraction, RF propagation within the accelerator envelope, RF parasitic modes, and stability of electrostatic septum operation. A design is presented that offers good optimization of these criteria.

Slides THOCN6 [5.266 MB]

THP003

High Power THz FEL Source Based on FFAG Betatron

FEL, electron, betatron, radiation

2142

A.Y. Murokh
RadiaBeam, Santa Monica, USA
S. Reiche
PSI, Villigen, Switzerland

A novel source of high power sub-mm waves is proposed that combines two well-known technologies – a betatron induction FFAG accelerator and a free electron laser (FEL). The system is configured as an FEL oscillator: the electron beam circulates in bi-periodic FFAG lattice and the external optical resonator maintains beam-radiation overlap through multiple orbits. Initial analysis shows that FEL gain and very high extraction efficiency are possible with modest injected beam current. A simplified interaction model and preliminary analysis results are presented.

THP005

High Power Cyclotron Complex for Neutron Production

cyclotron, proton, acceleration, electron

2145

Yu.G. Alenitsky, A.A. Glazov, G.A. Karamysheva, S.A. Kostromin, E. Samsonov
JINR, Dubna, Moscow Region, Russia
S.N. Dolya, L.M. Onischenko, S.B. Vorozhtsov, N.L. Zaplatin
JINR/DLNP, Dubna, Moscow region, Russia

Now the cyclotron seems as the most suitable accelerator for production of proton beams with energy up to Ep= 800 MeV and the power Pp=10 MW. There are some offers on creation of such complexes, all of them have common properties. A full cycle of acceleration consists of three stages: high-voltage injection with bunching of continuous beam, then preliminary acceleration in fore sectors cyclotron and acceleration up to the maximal energy 500-800 MeV in the ring cyclotron with six or more sectors. At the first stage of acceleration instead of high-voltage injection one can use the parallel work of two cyclotrons with injection in the subsequent cascade of a beam of the double intensity. In our department of New Accelerators the magnetic and high-frequency systems of a ring cyclotron on the energy 50 - 800 MeV (so-called “supercyclotron”) have been developed. A project of cyclotron injector with energy of protons about 10 MeV has been suggested as injector for Fasotron JINR LNP. It is offered to continue development of the project of cyclotron facility with energy of protons Ер ~ 800 MeV and average current of beam up to 10 mA.

THP105

Final Design of ILC RTML Extraction Line for Single Stage Bunch Compressor

sextupole, kicker, septum, damping

2321

S. Seletskiy
BNL, Upton, Long Island, New York, USA
N. Solyak
Fermilab, Batavia, USA

The use of single stage bunch compressor (BC) in the International Linear Collider (ILC) [1] Damping Ring to the Main Linac beamline (RTML) requires new design for the extraction line (EL). The EL located downstream of the BC will be used for both an emergency abort dumping of the beam and the tune-up continuous train-by-train extraction. It must accept both compressed and uncompressed beam with energy spread of 3.54% and 0.15% respectively. In this paper we report the final design that allowed minimizing the length of such extraction line while offsetting the beam dumps from the main line by 5m distance required for acceptable radiation level in the service tunnel. Proposed extraction line can accommodate beams with different energy spreads at the same time providing the beam size suitable for the aluminum ball dump window.

THP186

Lattice Design for ERL Options at SLAC

linac, emittance, injection, lattice

2465

Y. Nosochkov, Y. Cai, X. Huang, M.-H. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under Contract number DE-AC02 76SF00515.
SLAC is investigating long-range options for building a high performance light source machine while reusing the existing linac and PEP-II tunnels. One previously studied option is the PEP-X low emittance storage ring. The alternative option is based on a superconducting Energy Recovery Linac (ERL) and the PEP-X design. The ERL advantages are the low beam emittance, short bunch length and small energy spread leading to better qualities of the X-ray beams. Two ERL configurations differed by the location of the linac have been studied. Details of the lattice design and the results of beam transport simulations with the coherent synchrotron radiation effects are presented

THP192

Effect of Surface Roughness on the Emittance from GaAs Photocathode

electron, cathode, emittance, gun

2480

S.S. Karkare, I.V. Bazarov
Cornell University, Ithaca, New York, USA
L. Cultrera, A. Iyer, X. Liu, W.J. Schaff
CLASSE, Ithaca, New York, USA

Funding: This work is supported by NSF under Grant No. DMR- 0807731 and DOE under Grant No. DE-SC0003965.
The surface roughness of GaAs photocathodes used in the injector prototype for the ERL at Cornell University was measured and compared to that of the atomically polished GaAs crystal surface using the atomic force microscopy (AFM) technique. The results show at least an order of magnitude rise in the GaAs surface roughness after subjecting it to heat cleaning, prior to activation. An analytical model for photoemission that takes into account the effect of surface roughness has been developed. This model predicts emittance values close to the experimental observations, explains the experimentally observed variation of emittance with incident light wavelength and reconciles the discrepancies in experimental data.