LINAC2014 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
MOIOB02	Optimizing RF Linacs as Drivers for Inverse Compton Sources: the ELI-NP Case	electron, emittance, linac, photon	16
	C. Vaccarezza, D. Alesini, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, B. Spataro, P. Tomassini INFN/LNF, Frascati (Roma), Italy A. Bacci, D.T. Palmer, V. Petrillo, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy I.V. Drebot Universita' degli Studi di Milano e INFN, Milano, Italy A. Giribono, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy
	The design guide-lines of RF Linacs to fulfill the requirements of high spectral density Inverse Compton Sources for the photo-nuclear science are mostly mutuated from the expertise coming from high brightness electron Linacs driving X-ray FEL's. The main difference is the quest for maximum phase space density (instead of peak brightness), but many common issues and techniques are exploited, in order to achieve an optimum design and lay-out for the machine. A relevant example in this field is the design of the hybrid C-band multi-bunch RF Linacs for the ELI-NP Gamma Beam System, aiming at improving by two orders of magnitude the present state of the art in spectral density available for the gamma-ray beam produced.
	Slides MOIOB02 [2.542 MB]

MOIOB03	Generation and Acceleration of Low-Emittance, High-Current Electron Beams for SuperKEKB	emittance, gun, electron, wakefield	21
	M. Yoshida, N. Iida, S. Kazama, T. Natsui, Y. Ogawa, S. Ohsawa, L. Zang, X. Zhou KEK, Ibaraki, Japan
	KEK e⁻/e⁺ linac is now in a final stage of upgrade for SuperKEKB. One of the key issues is to stably generate and accelerate a low-emittance, high charge electron beam for SuperKEKB (a couple of single-bunched beams with a charge of 5 nC and a normalized emittance of 20 mm-mmrad each).
	Slides MOIOB03 [3.981 MB]

MOIOC03	Model and Beam Based Setup Procedures for a High Power Hadron Superconducting Linac	cavity, linac, simulation, quadrupole	41
	A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	This presentation will review methods for experimental determination of optimal operational set points in a multi-cavity superconducting high power hadron linac. A typical tuning process, including establishing correct acceleration profile and RMS bunch size matching, is based on comparison between measured data and the results of simulations from envelope, single and multi-particle models. Presence of significant space charge effects requires simulation and measurement of bunch dynamics in 3 dimensions to ensure low loss beam transport. This is especially difficult in a superconducting linac where use of interceptive diagnostics is usually restricted because of the risk of SRF cavity surface contamination. The procedures discussed here are based on non-interceptive diagnostics such as beam position monitors and laser wires, and conventional diagnostics devices such as wire scanners and bunch shape monitors installed outside the superconducting linac. The longitudinal Twiss analysis based on the BPM signals will be described. The superconducting SNS linac tuning experience will be used to demonstrate problems and their solution for real world linac tune-up procedures.
	Slides MOIOC03 [1.954 MB]

MOPP010	Low Charge State Laser Ion Source for the EBIS Injector	ion, injection, target, electron	64
	M. Okamura, J.G. Alessi, E.N. Beebe, T. Kanesue, C.J. Liaw, V. LoDestro, A.I. Pikin, D. Raparia, J. Ritter BNL, Upton, Long Island, New York, USA Y. Fuwa, S. Ikeda, M. Kumaki RIKEN, Saitama, Japan
	Funding: NASA In March 2014, we have successfully commissioned a newly designed low charge high brightness laser ion source (LIS) which delivers various singly charged heavy ions to the electron beam ion source (EBIS) at Brookhaven National Laboratory. Now the LIS is used at routine operation of the RHIC-AGS accelerator complex and is providing stable less-contaminated beams. The laser power density was optimized to provide singly charged ions with low material consumption rate. The nominal laser energy on the target is around 500 mJ with 1064 nm Nd:YAG of the wave length. The induced plasma by the laser is transported through a 3 m pipe to stretch ion beam pulse length to match the EBIS’s requirement and the degradation of the beam current caused by the long drift section of the pipe can be compensated by a longitudinal magnetic filed induced by a coil surrounding the pipe. We also employed a twin laser system to extend the beam width further. At the conference, we will discuss the effect of the new LIS on the various accelerated beams through the EBIS, RFQ and IH-linac.

MOPP030	CALIFES: A Multi-Purpose Electron Beam for Accelerator Technology Tests	electron, wakefield, acceleration, quadrupole	121
	J.L. Navarro Quirante, R. Corsini, W. Farabolini, D. Gamba, A. Grudiev, M.A. Khan, T. Lefèvre, S. Mazzoni, R. Pan, F. Peauger, F. Tecker, N. Vitoratou, K. Yaqub CERN, Geneva, Switzerland W. Farabolini, F. Peauger CEA/DSM/IRFU, France D. Gamba JAI, Oxford, United Kingdom M.A. Khan, K. Yaqub PINSTECH, Islamabad, Pakistan J. Ögren, R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden N. Vitoratou Thessaloniki University, Thessaloniki, Greece
	The Compact Linear Collider (CLIC) project aims to accelerate and collide electrons and positrons up to 3 TeV center-of-mass energy using a novel two-beam acceleration concept. To prove the feasibility of this technology the CLIC Test Facility CTF3 has been operated during the last years. CALIFES (Concept d’Accélérateur Linéaire pour Faisceau d’Electron Sonde) is an electron linac hosted in the CTF3 complex, which provides a flexible electron beam and the necessary equipment to probe both the two-beam acceleration concept and novel instrumentation to be used in the future CLIC collider. In this paper we describe the CALIFES Linac and its beam characteristics, present recent test results, outline its future program on two-beam module testing and finally discuss about possible future applications as a multi-purpose accelerator technology test facility.

MOPP058	Z-slicer: A Simple Scheme for Electron Beam Current Profile Shaping in a Linac	electron, radiation, dipole, cavity	183
	J.C.T. Thangaraj, C.M. Baffes, D.R. Broemmelsiek, D.J. Crawford, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA W.B. Wortley University of Rochester, Rochester, New York, USA
	Short bunches are a premium at accelerator facilities and their applications include THz generation, short bunch production, shaped bunch production, etc. In this work we report on the design of an experiment involving an electron beam about 50 MeV that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through un-affected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, transverse deflecting cavity. The tuning variable is only the RF-chirp and detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream. A thermal analysis suggests that MHz operation of the linac can be sustained under certain beam conditions without any damage to the slit mask.

MOPP068	The Fast Piezo-Based Frequency Tuner for SC CH-Cavities	cavity, resonance, simulation, operation	214
	M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany K. Aulenbacher HIM, Mainz, Germany W.A. Barth, V. Gettmann, S. Mickat GSI, Darmstadt, Germany
	Funding: Work supported by HIM, GSI, BMBF Contr. No 05P12RFRBL Superconducting structures are very susceptible to external influences due to their thin walls and their narrow bandwidth. Even small mechanical deformations caused by dynamic effects like microphonic noise, pressure fluctuations of the liquid helium bath or Lorentz-Force-Detuning can lead to resonance frequency changes of the cavity which are much larger than the bandwidth. To compensate the slow and fast resonance frequency variations during operation a compact frequency tuner prototype equipped with a stepper motor and a piezo actuator has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. In this paper, the tuner design and the results of first room temperature measurements of the tuner prototype are presented.
	Poster MOPP068 [2.304 MB]

MOPP112	Beam Dynamics of Multi Charge State Ions in RFQ Linac	ion, rfq, acceleration, ion-source	317
	Y. Fuwa, S. Ikeda, M. Kumaki RIKEN, Saitama, Japan Y. Fuwa, Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan T. Kanesue, M. Okamura BNL, Upton, Long Island, New York, USA
	Laser ion source with DPIS (Direct Plasma Injection Scheme) is a promising candidate for a pre-injector of the high-intensity accelerator. Eliminating LEBT (Low Energy Beam Transport) where the space charge effect is severe, DPIS provides high current ion beam from laser plasma at the entrance of a RFQ linac and ion beams are injected directly into the RFQ linac. However, the injected beam consists of multi charge state ions and their behavior in RFQ linac has not been well understood. In this research, we study the beam dynamics of multi charge state ions in a RFQ. Using the result of computer simulation, a set of 100MHz 4-rod RFQ vanes, which accelerates Al 12+ ion among various charge states of aluminum ions from 8.9 keV/u to 200 keV/u, is newly designed and fabricated to be tested with beams. The result of beam acceleration test using the vane will be reported.

MOPP123	Development Activities of Accelerator Instruments for SACLA	controls, acceleration, cavity, klystron	342
	Y. Otake, T. Asaka, T. Inagaki, C. Kondo, H. Maesaka, T. Ohshima, T. Sakurai, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan H. Ego, S. Matsubara JASRI/SPring-8, Hyogo-ken, Japan
	The X-ray free-electron laser, SACLA, is constantly operated for user experiments aimed at new science. Experimental users demand further experimental abilities, such as many experimental chances by using multi-X-ray beam lines, much better repeatability of the experiment conditions and further intense high-energy X-rays. To equip SACLA with these abilities in the future, we have developed a 2pi /3 CG acceleration structure with an acceleration gradient of over 45 MV/m to adapt operation for generating the intense high-energy X-rays. A high-voltage power supply to charge the PFN of a modulator, a klystron and an acceleration structure were developed to adapt operation for 120 pps operation from the present 30 pps, since 120 pps is more suitable for beam distribution to the multi-beam lines. To meet the experimental repeatability realized by stable timing in a pump-probe experiment, an optical-fiber length control system to mitigate timing drift below 1 fs for 10 minutes was developed. Highly precise cavity temperature control system in an injector for below ±2mK was also realized. Performances of our developed instruments were experimentally tested to be sufficient for our demands.

TUIOC01	Large Scale Testing of SRF Cavities and Modules	cryomodule, cavity, software, vacuum	426
	J. Świerbleski IFJ-PAN, Kraków, Poland
	Series production of SRF cavities, s.c. quadrupole packages and accelerator modules for the European XFEL is in full swing. Mid 2014 approx. 400 cavities will be tested, the testing of quadrupoles will be almost finished, and regular module testing will be established. Thus the talk should emphasize the quasi industrial testing of these components, of course including a good overview about the used somewhat unique AMTF infrastructure.
	Slides TUIOC01 [3.094 MB]

TUPP035	Transverse Profile and Emittance Measurements With a Laser Stripping System During the CERN LINAC4 Commissioning at 3 and 12 MeV	emittance, linac, detector, electron	506
	F. Roncarolo, E. Bravin, T. Hofmann, U. Raich, F. Zocca CERN, Geneva, Switzerland G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom C. Gabor STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	The CERN LINAC4 beam commissioning at 3 and 12 MeV was completed in 2014. A novel system for measuring the transverse beam profile and emittance, based on low power laser stripping and H⁰ detection using a diamond detector, was successfully tested at these two energies. The measurement results agree with the operational slit-grid method within a few percent in terms of both transverse profile and emittance. After describing the general system setup, this remarkable achievement is discussed in detail together with the present limitations, which will be addressed in order to design a laser based emittance monitor for the LINAC4 top energy of 160 MeV.

TUPP057	In Situ Measurement of Mechanical Vibrations of a 4-Rod RFQ at GSI	rfq, operation, vacuum, quadrupole	553
	P. Gerhard, L. Groening, K.-O. Voss GSI, Darmstadt, Germany
	A new 4-rod CW Radio Frequency Quadrupole was commissioned at the high charge state injector HLI at the UNILAC in 2009. It is in operation since 2010. At high rf amplitudes strong modulations of the rf reflection emerge, with a modulation frequency of approximately 500 Hz. They are attributed to mechanical oscillations of the rods, excited by the rf pulse. The high fraction of reflected rf power severely limits the pulse length and rf amplitude achievable. As these modulations could only be seen during the rf pulse by means of rf measurements, a direct observation of the mechanical vibrations was desirable. Such measurements have been conducted using a commercial laser vibrometer, allowing for the investigation of the mechanical behavior of the RFQ independent of the presence of rf power. After a short introduction of the method, the results will be presented and compared with rf measurements and simulations. : P. Gerhard et al., “Experience with a 4–Rod CW RFQ”, LINAC’12, Sept. 2012, Tel Aviv, THPB035

TUPP077	High Precision Manufacturing for LINAC's	linac, extraction, vacuum, controls	603
	F.M. Mirapeix, J. Añel HTS, Mendaro, Spain J. Amores, J. Presa, A. Urzainki DMP, Mendaro, Spain
	A big effort in R&D focused to the LINAC devices together with the know-how already deployed through emblematic projects places DMP in the state of the art of the extreme precision mechanics. This mechanic culture makes of DMP a natural partner in early stages of design or driver of a comprehensive solution, optimizing industrial risks, quality and due date. Surface roughness below 1 nanometer, figure errors better than 50 nanometers in OFE copper enhances lifetime and performance of many devices for LINAC's. Research in joining techniques and combining several alternative technologies to traditional machining improves figure stability and makes complex cooling systems possible.

TUPP091	3 BPM Study at PAL ITF	controls, electron, pick-up, interface	637
	M. Žnidarčič I-Tech, Solkan, Slovenia C. Kim, S.J. Lee PAL, Pohang, Kyungbuk, Republic of Korea
	Pohang Accelerator Laboratory (PAL) is building the 4th generation X-ray free electron laser (XFEL) machine. To examine the efficiency of various diagnostic devices an injector test facility (ITF) was constructed. The last part of the ITF is dedicated for evaluation of beam position measurement devices. A “3-BPM-study” was done with 3 Libera Single Pass E BPM modules that were connected to the 3 equidistantly positioned stripline sensors. The aim of the test was to measure the performances of the Libera Single Pass E devices with beam conditions similar to the real pal XFEL machine.

TUPP128	ECHO-enabled Tunable Terahertz Radiation Generation with a Laser-modulated Relativistic Electron Beam	radiation, electron, FEL, simulation	719
	D. Huang, Q. Gu, Z. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China D. Xiang Shanghai Jiao Tong University, Shanghai, People's Republic of China
	A new scheme to generate narrow-band tunable Terahertz (THz) radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme is demonstrated numerically with a start-to-end simulation using the beam parameters at Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV). The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear RF chirp and longitudinal space charge effect have also been studied in our article. We also briefly discuss how one may retrieve the beam longitudinal phase space through measurement of the THz density modulation. \end{abstract}

THPP058	A Review of Emittance Exchanger Beamlines: Past Experiments and Future Proposals	cavity, emittance, electron, experiment	982
	J.C.T. Thangaraj Fermilab, Batavia, Illinois, USA
	Emittance exchangers (EEX) are advanced phase space manipulation schemes where the transverse phase space of the electron beam is exchanged with the longitudinal phase space. The first experimentally demonstrated concept of the emittance exchanger at the A0 photoinjector at Fermilab used a transverse deflecting cavity (TDC) sandwiched between two doglegs. In this talk, I will briefly review the history of the emittance exchange beamline experiments from a low charge beam without RF chirp to a high charge beam with RF chirp including collective effects such as coherent synchrotron radiation. I will also describe how shaping application have been spawned based on EEX. I will then review future schemes that has been proposed and propose two additional schemes of EEX that can be implemented in existing modern linacs. As an example, we present an improved emittance exchanger scheme that uses a TDC sandwiched between two chicanes. The significant advantage of this scheme is that it allows the use of the expensive transverse deflecting cavity for diagnostics and still allows the flexibility to use the existing beamline either as a bunch compressor or an emittance exchanger.

THPP059	Z-Shaper: A Picosecond UV Laser Pulse Shaping Channel at the Advanced Superconducting Test Accelerator	experiment, electron, linac, controls	986
	J.C.T. Thangaraj, D.R. Edstrom, A.H. Lumpkin, J. Ruan Fermilab, Batavia, Illinois, USA B. Beaudoin UMD, College Park, Maryland, USA
	Many accelerator applications require a longitudinally shaped electron beam profile for studies ranging from THz generation to dielectric wakefield acceleration. An electron beam profile can be shaped through many techniques in both electron beam generation, such as with a DAZZLER or in ellipsoidal pulse generation, and beam transport, using an emittance exchanger or linearizing harmonic cavity. In this paper, shaping of a UV pulse with length on the order of picoseconds is examined using alpha-BBO crystals in the Advanced Superconducting Test Accelerator (ASTA) drive laser. A relatively economical solution to effect a predictable and tunable longitudinal bunch shape, profiles have been generated and observed using a Hamamatsu C5680 streak camera, and the results are compared with the analytical theory.

THPP107	Study on Polishing Method of Nb Surface by Periodic Reverse Current Electrolysis With Alkali Solution	experiment, cavity, SRF, operation	1102
	M. Umehara Nomura Plating Co, Ltd., Osaka, Japan H. Hayano, T. Saeki KEK, Ibaraki, Japan
	Currently, electropolising method is thought to be the best method for the final surface preparation of superconducting RF cavity to obtain high gradient. In this conventional electropolising method, the electrolyte is the mixture of fluoric and sulfuric acids. Therefore, the operation of this method is dangerous, and the equipment becomes expensive because all parts should be made of high density polyethylene or fluorocarbon resin to avoid metallic parts which suffers from corrosion by electrolyte. Moreover, sulfur is produced as byproduct in the electropolishing process and this causes degradation of cavity performance. In order to overcome these drawbacks, we studied new polishing method of Nb surface by periodic reverse current electrolysis with alkali solution which causes no sulfur and allows the usage of metallic parts to realize cost effective equipment. In the study, we performed experiment of Nb coupons by this new method and obtained as good surface roughness as conventional electropolishing method. In this article, we report the details of the study.

THPP119	Stabilization of Beam Performance due to Improvement of the Precise Temperature Regulation System of the SACLA Injector	controls, cavity, power-supply, feedback	1131
	T. Asaka, T. Hasegawa, H. Maesaka, Y. Otake, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	The temperature of rf cavities in the SACLA injector have to be precisely controlled to generate stable electron beam for XFEL users. To maintain the rf voltage and phase in the each cavity, the temperatures of all the cavities were kept within 28±0.04˚C by controlling the cooling water temperature. AC power supply of the controller to heat the cooling water was operated at 2Hz by PWM control with alternatively tuning on and off. The correlation between beam position variation and a leakage magnetic field due to applying the heater current of an AC power supply was found out. Although the cooling water temperature was controlled less than ±40mK, the laser intensity was affected by slight temperature drift. Therefore, thermometer modules were replaced to more precise ones with 1mK resolution. A new temperature regulation system using a continuous level control with DC power supply was installed. The fast fluctuation of the magnetic field leak by the heater current due to the PWM control was removed. Consequently, the beam position jitter in an undulator section was reduced to less than one-third and the laser position variation was suppressed within 20μm.

THPP120	Status of Radio-Frequency (RF) Deflectors at Radiabeam	electron, cavity, simulation, impedance	1134
	L. Faillace, R.B. Agustsson, J.J. Hartzell, A.Y. Murokh, S. Storms RadiaBeam, Santa Monica, California, USA
	Radiabeam Technologies recently developed an S-Band normal-conducting Radio-Frequency (NCRF) deflecting cavity for the Pohang Accelerator Laboratory (PAL) in order to perform longitudinal characterization of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 135 MeV electron beam parameters. The 1m-long PAL deflector is designed to operate at 2.856 GHz and features short filling time and femtosecond resolution. At the end of 2012, we delivered an X-band Traveling wave RF Deflector (XTD) to the ATF facility at Brookhaven National Lab. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. The XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. The XTD is currently being assembled at ATF for high-power operation and conditioning results will be reported soon.

THPP122	Development of Superconducting Cavities and Related Infrastructure for High Intensity Proton Linac for Spallation Neutron Source	cavity, niobium, linac, proton	1140
	S.C. Joshi, J. Dwivedi, P.D. Gupta, P.R. Hannurkar, V. Jain, P. Khare, P.K. Kush, G. Mundra, A. Puntambekar, S. Raghvendra, S.B. Roy, P. Shrivastava RRCAT, Indore (M.P.), India
	Raja Ramanna Centre for Advanced Technology has taken up a program on R&D activities of a 1 GeV, high intensity superconducting proton linac for a spallation neutron source. The proton linac will require a large number of superconducting Radio Frequency cavities ranging from low beta spoke resonators to medium and high beta multi-cell elliptical cavities at different RF frequencies. A dedicated facility is being set up for development of multi-cell superconducting cavities and their performance characterization. 1.3 GHz single-cell niobium cavities have been developed to establish the fabrication procedure. These cavities has exhibited high quality factor with an accelerating gradients up to 37 MV/m. A novel technique of laser welding of 1.3 GHz niobium cavity has been developed and demonstrated performance comparable to electron beam welded cavity. A dedicated facility for SCRF cavity forming, machining, electron beam welding, RF characterization, cavity tuning and cavity processing is being set up. To characterize a SCRF cavity at 2K, a vertical test stand has been developed and a horizontal test stand has been designed.

FRIOA06	AWAKE: Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN	plasma, proton, electron, experiment	1196
	E. Gschwendtner CERN, Geneva, Switzerland
	Plasma wakefield acceleration is a promising alternative reaching accelerating fields a magnitude of up to 3 higher (GV/m) when compared to conventional RF acceleration. AWAKE, world’s first proton-driven plasma wakefield experiment, was launched at CERN to verify this concept. In this experiment proton bunches at 400 GeV/c will be extracted from the CERN SPS and sent to the plasma cell, where the proton beam drives the plasma wakefields and creates a large accelerating field. This large gradient of ~GV/m can be achieved by relying on the self-modulation instability (SMI) of the proton beam; when seeded by ionization through a short laser pulse, a train of micro-bunches with a period on the order of the plasma wavelength (~mm) develops, which can drive such a large amplitude wake from a long proton bunch (~12 cm). An electron beam will be injected into the plasma to probe the accelerating wakefield. The AWAKE experiment is being installed at CERN in the former CNGS facility, which must be modified to match the AWAKE requirements. First proton beam to the plasma cell is expected by end 2016.
	Slides FRIOA06 [7.276 MB]

Paper

Title

Other Keywords

Page

MOIOB02

Optimizing RF Linacs as Drivers for Inverse Compton Sources: the ELI-NP Case

electron, emittance, linac, photon

16

C. Vaccarezza, D. Alesini, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, B. Spataro, P. Tomassini
INFN/LNF, Frascati (Roma), Italy
A. Bacci, D.T. Palmer, V. Petrillo, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
I.V. Drebot
Universita' degli Studi di Milano e INFN, Milano, Italy
A. Giribono, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

The design guide-lines of RF Linacs to fulfill the requirements of high spectral density Inverse Compton Sources for the photo-nuclear science are mostly mutuated from the expertise coming from high brightness electron Linacs driving X-ray FEL's. The main difference is the quest for maximum phase space density (instead of peak brightness), but many common issues and techniques are exploited, in order to achieve an optimum design and lay-out for the machine. A relevant example in this field is the design of the hybrid C-band multi-bunch RF Linacs for the ELI-NP Gamma Beam System, aiming at improving by two orders of magnitude the present state of the art in spectral density available for the gamma-ray beam produced.

Slides MOIOB02 [2.542 MB]

MOIOB03

Generation and Acceleration of Low-Emittance, High-Current Electron Beams for SuperKEKB

emittance, gun, electron, wakefield

21

M. Yoshida, N. Iida, S. Kazama, T. Natsui, Y. Ogawa, S. Ohsawa, L. Zang, X. Zhou
KEK, Ibaraki, Japan

KEK e⁻/e⁺ linac is now in a final stage of upgrade for SuperKEKB. One of the key issues is to stably generate and accelerate a low-emittance, high charge electron beam for SuperKEKB (a couple of single-bunched beams with a charge of 5 nC and a normalized emittance of 20 mm-mmrad each).

Slides MOIOB03 [3.981 MB]

MOIOC03

Model and Beam Based Setup Procedures for a High Power Hadron Superconducting Linac

cavity, linac, simulation, quadrupole

41

A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

This presentation will review methods for experimental determination of optimal operational set points in a multi-cavity superconducting high power hadron linac. A typical tuning process, including establishing correct acceleration profile and RMS bunch size matching, is based on comparison between measured data and the results of simulations from envelope, single and multi-particle models. Presence of significant space charge effects requires simulation and measurement of bunch dynamics in 3 dimensions to ensure low loss beam transport. This is especially difficult in a superconducting linac where use of interceptive diagnostics is usually restricted because of the risk of SRF cavity surface contamination. The procedures discussed here are based on non-interceptive diagnostics such as beam position monitors and laser wires, and conventional diagnostics devices such as wire scanners and bunch shape monitors installed outside the superconducting linac. The longitudinal Twiss analysis based on the BPM signals will be described. The superconducting SNS linac tuning experience will be used to demonstrate problems and their solution for real world linac tune-up procedures.

Slides MOIOC03 [1.954 MB]

MOPP010

Low Charge State Laser Ion Source for the EBIS Injector

ion, injection, target, electron

64

M. Okamura, J.G. Alessi, E.N. Beebe, T. Kanesue, C.J. Liaw, V. LoDestro, A.I. Pikin, D. Raparia, J. Ritter
BNL, Upton, Long Island, New York, USA
Y. Fuwa, S. Ikeda, M. Kumaki
RIKEN, Saitama, Japan

Funding: NASA
In March 2014, we have successfully commissioned a newly designed low charge high brightness laser ion source (LIS) which delivers various singly charged heavy ions to the electron beam ion source (EBIS) at Brookhaven National Laboratory. Now the LIS is used at routine operation of the RHIC-AGS accelerator complex and is providing stable less-contaminated beams. The laser power density was optimized to provide singly charged ions with low material consumption rate. The nominal laser energy on the target is around 500 mJ with 1064 nm Nd:YAG of the wave length. The induced plasma by the laser is transported through a 3 m pipe to stretch ion beam pulse length to match the EBIS’s requirement and the degradation of the beam current caused by the long drift section of the pipe can be compensated by a longitudinal magnetic filed induced by a coil surrounding the pipe. We also employed a twin laser system to extend the beam width further. At the conference, we will discuss the effect of the new LIS on the various accelerated beams through the EBIS, RFQ and IH-linac.

MOPP030

CALIFES: A Multi-Purpose Electron Beam for Accelerator Technology Tests

electron, wakefield, acceleration, quadrupole

121

J.L. Navarro Quirante, R. Corsini, W. Farabolini, D. Gamba, A. Grudiev, M.A. Khan, T. Lefèvre, S. Mazzoni, R. Pan, F. Peauger, F. Tecker, N. Vitoratou, K. Yaqub
CERN, Geneva, Switzerland
W. Farabolini, F. Peauger
CEA/DSM/IRFU, France
D. Gamba
JAI, Oxford, United Kingdom
M.A. Khan, K. Yaqub
PINSTECH, Islamabad, Pakistan
J. Ögren, R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden
N. Vitoratou
Thessaloniki University, Thessaloniki, Greece

The Compact Linear Collider (CLIC) project aims to accelerate and collide electrons and positrons up to 3 TeV center-of-mass energy using a novel two-beam acceleration concept. To prove the feasibility of this technology the CLIC Test Facility CTF3 has been operated during the last years. CALIFES (Concept d’Accélérateur Linéaire pour Faisceau d’Electron Sonde) is an electron linac hosted in the CTF3 complex, which provides a flexible electron beam and the necessary equipment to probe both the two-beam acceleration concept and novel instrumentation to be used in the future CLIC collider. In this paper we describe the CALIFES Linac and its beam characteristics, present recent test results, outline its future program on two-beam module testing and finally discuss about possible future applications as a multi-purpose accelerator technology test facility.

MOPP058

Z-slicer: A Simple Scheme for Electron Beam Current Profile Shaping in a Linac

electron, radiation, dipole, cavity

183

J.C.T. Thangaraj, C.M. Baffes, D.R. Broemmelsiek, D.J. Crawford, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
W.B. Wortley
University of Rochester, Rochester, New York, USA

Short bunches are a premium at accelerator facilities and their applications include THz generation, short bunch production, shaped bunch production, etc. In this work we report on the design of an experiment involving an electron beam about 50 MeV that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through un-affected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, transverse deflecting cavity. The tuning variable is only the RF-chirp and detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream. A thermal analysis suggests that MHz operation of the linac can be sustained under certain beam conditions without any damage to the slit mask.

MOPP068

The Fast Piezo-Based Frequency Tuner for SC CH-Cavities

cavity, resonance, simulation, operation

214

M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
K. Aulenbacher
HIM, Mainz, Germany
W.A. Barth, V. Gettmann, S. Mickat
GSI, Darmstadt, Germany

Funding: Work supported by HIM, GSI, BMBF Contr. No 05P12RFRBL
Superconducting structures are very susceptible to external influences due to their thin walls and their narrow bandwidth. Even small mechanical deformations caused by dynamic effects like microphonic noise, pressure fluctuations of the liquid helium bath or Lorentz-Force-Detuning can lead to resonance frequency changes of the cavity which are much larger than the bandwidth. To compensate the slow and fast resonance frequency variations during operation a compact frequency tuner prototype equipped with a stepper motor and a piezo actuator has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. In this paper, the tuner design and the results of first room temperature measurements of the tuner prototype are presented.

Poster MOPP068 [2.304 MB]

MOPP112

Beam Dynamics of Multi Charge State Ions in RFQ Linac

ion, rfq, acceleration, ion-source

317

Y. Fuwa, S. Ikeda, M. Kumaki
RIKEN, Saitama, Japan
Y. Fuwa, Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
T. Kanesue, M. Okamura
BNL, Upton, Long Island, New York, USA

Laser ion source with DPIS (Direct Plasma Injection Scheme) is a promising candidate for a pre-injector of the high-intensity accelerator. Eliminating LEBT (Low Energy Beam Transport) where the space charge effect is severe, DPIS provides high current ion beam from laser plasma at the entrance of a RFQ linac and ion beams are injected directly into the RFQ linac. However, the injected beam consists of multi charge state ions and their behavior in RFQ linac has not been well understood. In this research, we study the beam dynamics of multi charge state ions in a RFQ. Using the result of computer simulation, a set of 100MHz 4-rod RFQ vanes, which accelerates Al 12+ ion among various charge states of aluminum ions from 8.9 keV/u to 200 keV/u, is newly designed and fabricated to be tested with beams. The result of beam acceleration test using the vane will be reported.

MOPP123

Development Activities of Accelerator Instruments for SACLA

controls, acceleration, cavity, klystron

342

Y. Otake, T. Asaka, T. Inagaki, C. Kondo, H. Maesaka, T. Ohshima, T. Sakurai, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
H. Ego, S. Matsubara
JASRI/SPring-8, Hyogo-ken, Japan

The X-ray free-electron laser, SACLA, is constantly operated for user experiments aimed at new science. Experimental users demand further experimental abilities, such as many experimental chances by using multi-X-ray beam lines, much better repeatability of the experiment conditions and further intense high-energy X-rays. To equip SACLA with these abilities in the future, we have developed a 2pi /3 CG acceleration structure with an acceleration gradient of over 45 MV/m to adapt operation for generating the intense high-energy X-rays. A high-voltage power supply to charge the PFN of a modulator, a klystron and an acceleration structure were developed to adapt operation for 120 pps operation from the present 30 pps, since 120 pps is more suitable for beam distribution to the multi-beam lines. To meet the experimental repeatability realized by stable timing in a pump-probe experiment, an optical-fiber length control system to mitigate timing drift below 1 fs for 10 minutes was developed. Highly precise cavity temperature control system in an injector for below ±2mK was also realized. Performances of our developed instruments were experimentally tested to be sufficient for our demands.

TUIOC01

Large Scale Testing of SRF Cavities and Modules

cryomodule, cavity, software, vacuum

426

J. Świerbleski
IFJ-PAN, Kraków, Poland

Series production of SRF cavities, s.c. quadrupole packages and accelerator modules for the European XFEL is in full swing. Mid 2014 approx. 400 cavities will be tested, the testing of quadrupoles will be almost finished, and regular module testing will be established. Thus the talk should emphasize the quasi industrial testing of these components, of course including a good overview about the used somewhat unique AMTF infrastructure.

Slides TUIOC01 [3.094 MB]

TUPP035

Transverse Profile and Emittance Measurements With a Laser Stripping System During the CERN LINAC4 Commissioning at 3 and 12 MeV

emittance, linac, detector, electron

506

F. Roncarolo, E. Bravin, T. Hofmann, U. Raich, F. Zocca
CERN, Geneva, Switzerland
G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
C. Gabor
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The CERN LINAC4 beam commissioning at 3 and 12 MeV was completed in 2014. A novel system for measuring the transverse beam profile and emittance, based on low power laser stripping and H⁰ detection using a diamond detector, was successfully tested at these two energies. The measurement results agree with the operational slit-grid method within a few percent in terms of both transverse profile and emittance. After describing the general system setup, this remarkable achievement is discussed in detail together with the present limitations, which will be addressed in order to design a laser based emittance monitor for the LINAC4 top energy of 160 MeV.

TUPP057

In Situ Measurement of Mechanical Vibrations of a 4-Rod RFQ at GSI

rfq, operation, vacuum, quadrupole

553

P. Gerhard, L. Groening, K.-O. Voss
GSI, Darmstadt, Germany

A new 4-rod CW Radio Frequency Quadrupole was commissioned at the high charge state injector HLI at the UNILAC in 2009. It is in operation since 2010*. At high rf amplitudes strong modulations of the rf reflection emerge, with a modulation frequency of approximately 500 Hz. They are attributed to mechanical oscillations of the rods, excited by the rf pulse. The high fraction of reflected rf power severely limits the pulse length and rf amplitude achievable. As these modulations could only be seen during the rf pulse by means of rf measurements, a direct observation of the mechanical vibrations was desirable. Such measurements have been conducted using a commercial laser vibrometer, allowing for the investigation of the mechanical behavior of the RFQ independent of the presence of rf power. After a short introduction of the method, the results will be presented and compared with rf measurements and simulations.
*: P. Gerhard et al., “Experience with a 4–Rod CW RFQ”, LINAC’12, Sept. 2012, Tel Aviv, THPB035

TUPP077

High Precision Manufacturing for LINAC's

linac, extraction, vacuum, controls

603

F.M. Mirapeix, J. Añel
HTS, Mendaro, Spain
J. Amores, J. Presa, A. Urzainki
DMP, Mendaro, Spain

A big effort in R&D focused to the LINAC devices together with the know-how already deployed through emblematic projects places DMP in the state of the art of the extreme precision mechanics. This mechanic culture makes of DMP a natural partner in early stages of design or driver of a comprehensive solution, optimizing industrial risks, quality and due date. Surface roughness below 1 nanometer, figure errors better than 50 nanometers in OFE copper enhances lifetime and performance of many devices for LINAC's. Research in joining techniques and combining several alternative technologies to traditional machining improves figure stability and makes complex cooling systems possible.

TUPP091

3 BPM Study at PAL ITF

controls, electron, pick-up, interface

637

M. Žnidarčič
I-Tech, Solkan, Slovenia
C. Kim, S.J. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory (PAL) is building the 4th generation X-ray free electron laser (XFEL) machine. To examine the efficiency of various diagnostic devices an injector test facility (ITF) was constructed. The last part of the ITF is dedicated for evaluation of beam position measurement devices. A “3-BPM-study” was done with 3 Libera Single Pass E BPM modules that were connected to the 3 equidistantly positioned stripline sensors. The aim of the test was to measure the performances of the Libera Single Pass E devices with beam conditions similar to the real pal XFEL machine.

TUPP128

ECHO-enabled Tunable Terahertz Radiation Generation with a Laser-modulated Relativistic Electron Beam

radiation, electron, FEL, simulation

719

D. Huang, Q. Gu, Z. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

A new scheme to generate narrow-band tunable Terahertz (THz) radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme is demonstrated numerically with a start-to-end simulation using the beam parameters at Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV). The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear RF chirp and longitudinal space charge effect have also been studied in our article. We also briefly discuss how one may retrieve the beam longitudinal phase space through measurement of the THz density modulation. \end{abstract}

THPP058

A Review of Emittance Exchanger Beamlines: Past Experiments and Future Proposals

cavity, emittance, electron, experiment

982

J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA

Emittance exchangers (EEX) are advanced phase space manipulation schemes where the transverse phase space of the electron beam is exchanged with the longitudinal phase space. The first experimentally demonstrated concept of the emittance exchanger at the A0 photoinjector at Fermilab used a transverse deflecting cavity (TDC) sandwiched between two doglegs. In this talk, I will briefly review the history of the emittance exchange beamline experiments from a low charge beam without RF chirp to a high charge beam with RF chirp including collective effects such as coherent synchrotron radiation. I will also describe how shaping application have been spawned based on EEX. I will then review future schemes that has been proposed and propose two additional schemes of EEX that can be implemented in existing modern linacs. As an example, we present an improved emittance exchanger scheme that uses a TDC sandwiched between two chicanes. The significant advantage of this scheme is that it allows the use of the expensive transverse deflecting cavity for diagnostics and still allows the flexibility to use the existing beamline either as a bunch compressor or an emittance exchanger.

THPP059

Z-Shaper: A Picosecond UV Laser Pulse Shaping Channel at the Advanced Superconducting Test Accelerator

experiment, electron, linac, controls

986

J.C.T. Thangaraj, D.R. Edstrom, A.H. Lumpkin, J. Ruan
Fermilab, Batavia, Illinois, USA
B. Beaudoin
UMD, College Park, Maryland, USA

Many accelerator applications require a longitudinally shaped electron beam profile for studies ranging from THz generation to dielectric wakefield acceleration. An electron beam profile can be shaped through many techniques in both electron beam generation, such as with a DAZZLER or in ellipsoidal pulse generation, and beam transport, using an emittance exchanger or linearizing harmonic cavity. In this paper, shaping of a UV pulse with length on the order of picoseconds is examined using alpha-BBO crystals in the Advanced Superconducting Test Accelerator (ASTA) drive laser. A relatively economical solution to effect a predictable and tunable longitudinal bunch shape, profiles have been generated and observed using a Hamamatsu C5680 streak camera, and the results are compared with the analytical theory.

THPP107

Study on Polishing Method of Nb Surface by Periodic Reverse Current Electrolysis With Alkali Solution

experiment, cavity, SRF, operation

1102

M. Umehara
Nomura Plating Co, Ltd., Osaka, Japan
H. Hayano, T. Saeki
KEK, Ibaraki, Japan

Currently, electropolising method is thought to be the best method for the final surface preparation of superconducting RF cavity to obtain high gradient. In this conventional electropolising method, the electrolyte is the mixture of fluoric and sulfuric acids. Therefore, the operation of this method is dangerous, and the equipment becomes expensive because all parts should be made of high density polyethylene or fluorocarbon resin to avoid metallic parts which suffers from corrosion by electrolyte. Moreover, sulfur is produced as byproduct in the electropolishing process and this causes degradation of cavity performance. In order to overcome these drawbacks, we studied new polishing method of Nb surface by periodic reverse current electrolysis with alkali solution which causes no sulfur and allows the usage of metallic parts to realize cost effective equipment. In the study, we performed experiment of Nb coupons by this new method and obtained as good surface roughness as conventional electropolishing method. In this article, we report the details of the study.

THPP119

Stabilization of Beam Performance due to Improvement of the Precise Temperature Regulation System of the SACLA Injector

controls, cavity, power-supply, feedback

1131

T. Asaka, T. Hasegawa, H. Maesaka, Y. Otake, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

The temperature of rf cavities in the SACLA injector have to be precisely controlled to generate stable electron beam for XFEL users. To maintain the rf voltage and phase in the each cavity, the temperatures of all the cavities were kept within 28±0.04˚C by controlling the cooling water temperature. AC power supply of the controller to heat the cooling water was operated at 2Hz by PWM control with alternatively tuning on and off. The correlation between beam position variation and a leakage magnetic field due to applying the heater current of an AC power supply was found out. Although the cooling water temperature was controlled less than ±40mK, the laser intensity was affected by slight temperature drift. Therefore, thermometer modules were replaced to more precise ones with 1mK resolution. A new temperature regulation system using a continuous level control with DC power supply was installed. The fast fluctuation of the magnetic field leak by the heater current due to the PWM control was removed. Consequently, the beam position jitter in an undulator section was reduced to less than one-third and the laser position variation was suppressed within 20μm.

THPP120

Status of Radio-Frequency (RF) Deflectors at Radiabeam

electron, cavity, simulation, impedance

1134

L. Faillace, R.B. Agustsson, J.J. Hartzell, A.Y. Murokh, S. Storms
RadiaBeam, Santa Monica, California, USA

Radiabeam Technologies recently developed an S-Band normal-conducting Radio-Frequency (NCRF) deflecting cavity for the Pohang Accelerator Laboratory (PAL) in order to perform longitudinal characterization of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 135 MeV electron beam parameters. The 1m-long PAL deflector is designed to operate at 2.856 GHz and features short filling time and femtosecond resolution. At the end of 2012, we delivered an X-band Traveling wave RF Deflector (XTD) to the ATF facility at Brookhaven National Lab. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. The XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. The XTD is currently being assembled at ATF for high-power operation and conditioning results will be reported soon.

THPP122

Development of Superconducting Cavities and Related Infrastructure for High Intensity Proton Linac for Spallation Neutron Source

cavity, niobium, linac, proton

1140

S.C. Joshi, J. Dwivedi, P.D. Gupta, P.R. Hannurkar, V. Jain, P. Khare, P.K. Kush, G. Mundra, A. Puntambekar, S. Raghvendra, S.B. Roy, P. Shrivastava
RRCAT, Indore (M.P.), India

Raja Ramanna Centre for Advanced Technology has taken up a program on R&D activities of a 1 GeV, high intensity superconducting proton linac for a spallation neutron source. The proton linac will require a large number of superconducting Radio Frequency cavities ranging from low beta spoke resonators to medium and high beta multi-cell elliptical cavities at different RF frequencies. A dedicated facility is being set up for development of multi-cell superconducting cavities and their performance characterization. 1.3 GHz single-cell niobium cavities have been developed to establish the fabrication procedure. These cavities has exhibited high quality factor with an accelerating gradients up to 37 MV/m. A novel technique of laser welding of 1.3 GHz niobium cavity has been developed and demonstrated performance comparable to electron beam welded cavity. A dedicated facility for SCRF cavity forming, machining, electron beam welding, RF characterization, cavity tuning and cavity processing is being set up. To characterize a SCRF cavity at 2K, a vertical test stand has been developed and a horizontal test stand has been designed.

FRIOA06

AWAKE: Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

plasma, proton, electron, experiment

1196

E. Gschwendtner
CERN, Geneva, Switzerland

Plasma wakefield acceleration is a promising alternative reaching accelerating fields a magnitude of up to 3 higher (GV/m) when compared to conventional RF acceleration. AWAKE, world’s first proton-driven plasma wakefield experiment, was launched at CERN to verify this concept. In this experiment proton bunches at 400 GeV/c will be extracted from the CERN SPS and sent to the plasma cell, where the proton beam drives the plasma wakefields and creates a large accelerating field. This large gradient of ~GV/m can be achieved by relying on the self-modulation instability (SMI) of the proton beam; when seeded by ionization through a short laser pulse, a train of micro-bunches with a period on the order of the plasma wavelength (~mm) develops, which can drive such a large amplitude wake from a long proton bunch (~12 cm). An electron beam will be injected into the plasma to probe the accelerating wakefield. The AWAKE experiment is being installed at CERN in the former CNGS facility, which must be modified to match the AWAKE requirements. First proton beam to the plasma cell is expected by end 2016.

Slides FRIOA06 [7.276 MB]