LINAC2014 - List of Keywords (impedance)

Paper	Title	Other Keywords	Page
MOPP020	Input Couplers for Cornell ERL	linac, cryomodule, coupling, cavity	95
	R.G. Eichhorn, P. Quigley, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S.A. Belomestnykh BNL, Upton, Long Island, New York, USA
	Cornell has developed two types of input couplers for the Energy Recovery Linac (ERL) Project. Both couplers are 1.3 GHz CW coaxial couplers. The coupler for ERL injector is a 65 kW CW coupler with variable coupling (Qext = 9E4 to 9E5). The coupler for ERL main linac is a 5 kW CW coupler with fixed coupling. It can be easily modified for variable coupling operation. Couplers have been tested on test stands and in cryomodules and showed good performance.

MOPP028	New Criterion for Shape Optimization of Normal-Conducting Accelerator Cells for High-Gradient Applications	factory, database, resonance, simulation	114
	K.N. Sjobak, A. Grudiev CERN, Geneva, Switzerland E. Adli University of Oslo, Oslo, Norway
	When optimizing the shape of high-gradient accelerating cells, the goal has traditionally been to minimize the peak surface electric field / gradient, or more recently minimizing the peak modified Poynting vector / gradient squared. This paper presents a method for directly comparing these quan- tities, as well as the power flow per circumference / gradient squared. The method works by comparing the maximum tolerable gradient at a fixed pulse length and breakdown rate that can be expected from the different constraints. The paper also presents a set of 120° phase-advance cells for traveling wave structures, which were designed for the new CLIC main linac accelerating structure, and which are optimized according to these criteria.

MOPP118	C-Band Load Development for the High Power Test of the SwissFEL RF Pulse Compressor	cavity, klystron, vacuum, coupling	329
	A. Citterio, J. Stettler, R. Zennaro PSI, Villigen PSI, Switzerland
	The SwissFEL C-band Linac will have 26 RF modules, each one consisting of a solid-state modulator and a 50 MW klystron that feeds a pulse compressor and four two meters long accelerating structures. The pulse compressor is of the Barrel Open Cavity type (BOC). A first prototype was successfully produced and high-power tested, reaching for full power klystron operation a peak power of 300 MW. For testing this BOC at maximum RF power, a broadband load was designed and built, based on a ridge waveguide design and high permeability stainless steel. Based on the experience gained at CERN for CLIC X-band high power loads, the RF design of the load was optimized to ensure high losses for a quite large range of magnetic steels. Test pieces were realized in three different magnetic steels to choose the best suited material commercially available. This paper reports about the RF design, material study, production and impressive high power results of this C-band load.

MOPP122	Construction of the New Amplifiers for the RIKEN-LINAC	ion, heavy-ion, cathode, controls	339
	K. Suda, E. Ikezawa, O. Kamigaito, N. Sakamoto, K. Yamada RIKEN Nishina Center, Wako, Japan Y. Touchi SHI, Tokyo, Japan
	New tetrode based amplifiers have been constructed for the RIKEN heavy-ion linac, so called RILAC[1], replacing 36-year-old amplifiers to improve their reliability as a main injector for the RIBF accelerator complex. The RILAC is a DC machine and their frequency are tunable between 18 to 40 MHz so as to be capable of accelerating heavy ions with mass-to-charge (m/q) ratios up to 28. The new rf amplifier is based on a tetrode THALES/SIEMENS RS2042SK coupled with a tetrode THALES/SIEMENS RS2012CJ with a grounded grid circuit. The maximum output power is 100 kW with a frequency ranging from 18 to 40 MHz. The amplifier was originally designed for RIKEN Ring Cyclotron. Since we have many experiences with this type of amplifier, some modification to avoid exciting the parasitic modes which might damage the cavity and/or the amplifier itself. Their construction started in April 2013 and installation was performed in January 2014. After the installation their commissioning has been successfully made. For a beam service started in this March the new amplifiers were operated without any troubles. [1]M. Odera et al., Nucl. Instrum. and Methods, 227, 187(1984).
	Poster MOPP122 [16.391 MB]

MOPP125	Comparison of Normal Conducting High Energy Accelerating Structures for a Moderate Operating Frequency	coupling, linac, Windows, proton	348
	V.V. Paramonov RAS/INR, Moscow, Russia
	The progress in the CERN Linac 4 project confirms the very attractive possibility for single frequency high intensity high energy normal conducting hadron linac. The important part of such linac is the accelerating structure for high energy part. Parameters of possible accelerating structures, referring to PIMS, at operating frequency 352 MHz are considered for proton energy up to 600 MeV. The set of parameters, such as dimensions, RF efficiency, field stability, cooling capability, vacuum conductivity, are considered and compared.

MOPP126	Untrapped HOM Radiation Absorption in the LCLS-II Cryomodules	HOM, cryomodule, cavity, linac	351
	K.L.F. Bane, C. Adolphsen, C.D. Nantista, T.O. Raubenheimer SLAC, Menlo Park, California, USA A. Saini, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Department of Energy contract DE–AC02–76SF00515. The superconducting cavities in the continuous wave (CW) linacs of LCLS-II are designed to operate at 2 K, where cooling costs are very expensive. One source of heat is presented by the higher order mode (HOM) power deposited by the beam. Due to the very short bunch length-especially in L3 the final linac-the LCLS-II beam spectrum extends into the terahertz range. Ceramic absorbers, at 70 K and located between cryomodules, are meant to absorb much of this power. In this report we perform two kinds of calculations to estimate the effectiveness of the absorbers and the amount of beam power that needs to be removed at 2 K.

TUPP007	Multi Gigawatt High Current Pulsed Electron Accelerator Technology Development Program at BARC	electron, linac, high-voltage, induction	456
	A. Sharma, R. Agarwal, M. Beg, R. Chandra, H. Choudhary, L.M. Gantayet, S.R. Ghodke, TS. Kolge, R. Kumar, S. Mitra, K.C. Mittal, A.S. Patel, A. Roy, P.C. Saroj, K. Senthil, V.K. Sharma, S.K. Singh BARC, Mumbai, India
	High current intense electron beams were investigated earlier for Flash X-rays and nuclear electromagnetic pulse generation. Starting with moderate parameters of 200 kV, 6 kA, 60 ns pulsed electron beam source from a system named Kilo Ampere Linear Injector (KALI-75) our latest development is KALI-30 GW system rated for 1 MV, 30 kA, 80 ns. First repetitive pulse LINAC without spark gap switching was developed as Linear Induction Accelerator (LIA-200) for technology demonstrations at 100 Hz. Also a repetitive Marx generator coupled reflex triode system to operate at 10 Hz. Next to this series of development LIA-400 has been developed to a capacity of 400 kV, 4 kA, 100 ns, 300 Hz. To make these pulse power systems applicable for big LINAC projects like nToF studies or ADS program, a high current electron gun has also been developed to give 100 A, 2 ns,10 Hz pulses. References [1].Amitava Roy et al, Journal of App. Physics 103, 2008. [2].D. D. P. Kumar, et al. Rev. Sci. Inst., vol. 78, no. 11, 2007. [3].Archana Sharma, et al., IEEE-PS Vol. 39, No. 5, 2011.

TUPP072	Studies on Wake Field in Annular Coupled Structure	wakefield, cavity, linac, acceleration	593
	Y. Liu, T. Maruta KEK/JAEA, Ibaraki-Ken, Japan K. Futatsukawa KEK, Ibaraki, Japan A. Miura JAEA/J-PARC, Tokai-mura, Japan
	LINAC injector of J-PARC (Japan Proton Accelerator Research Complex) was recently successfully upgraded from 181 MeV to 400 MeV, applying a type of coupled cavity linac (CCL) structure ACS (Annular Coupled Structure). It was warmly discussed since very beginning on the wake field in the ACS cavities, where there are CCL modes with the same number as that of cells within ~50 MHz, possibly resonating with high intensity proton/H⁻ beams. One of the most important effects from the wake field is the influence on the ACS phase scan. Analytical and simulation studies, as well as the countermeasures were prepared before the energy upgrade. Fortunately we found that detuning of the ACS was unnecessary, which helped to save much work in the commissioning. In addition we got chance to make experiment studies. It was also discussed why the wake field is not so serious as we expected at the very beginning.

TUPP108	HOM and Impedance Study of RF Separators for LCLS II	cavity, HOM, dipole, superconducting-RF	674
	S.U. De Silva, J.R. Delayen, B.R.P. Gamage, G.A. Krafft, T. Satogata ODU, Norfolk, Virginia, USA R.G. Olave Old Dominion University, Norfolk, Virginia, USA
	The LCLS-II upgrade requires an rf spreader system to guide bunches into a switchyard delivering beam to two undulators and the primary beam dump. The beam pattern therefore needs a 3-way beam spreader. An rf deflecting cavity concept was proposed that includes both superconducting and normal conducting options. We characterize the higher order modes (HOM) of these rf separator cavities and evaluate beam dynamics effects due to potential HOM excitation. This study includes both short term wake and multi-bunch effects.
	Poster TUPP108 [1.032 MB]

TUPP113	High RF Power Test of Coupled RFQ-SFRFQ Cavity	cavity, rfq, simulation, detector	689
	W.L. Xia, J.E. Chen, S.L. Gao, F.J. Jia, Y.R. Lu, Z. Wang, J. Zhao, K. Zhu PKU, Beijing, People's Republic of China
	Funding: This work was supported in part by the National Natural Science Foundation of China under Grant No. 11075008, 11079001 and 11175009. A new combined accelerator that couples radio frequency quadrupole (RFQ) and separated function radio frequency quadrupole (SFRFQ) in a single cavity has been designed and manufactured. Recently, the performance of the cavity under high RF power was tested with an upgraded RF power source. The inter-vane voltages of both RFQ section and SFRFQ section were measured by using high purity germanium detector and the corresponding measurement system. The measured shunt impedance is about 546.9 kΩ•m, which means the cavity needs 19.5 kW for the designed inter-vane voltage of 65 kV. The results are well consistent with the cavity design.
	Poster TUPP113 [0.764 MB]

TUPP122	Roughness Tolerances in the Undulator Vacuum Chamber of LCLS-II	undulator, vacuum, wakefield, FEL	708
	K.L.F. Bane, G.V. Stupakov SLAC, Menlo Park, California, USA
	Funding: Work supported by Department of Energy contract DE–AC02–76SF00515. In LCLS-II, after acceleration and compression and just before entering the undulator, the beam passes through roughly 2.5 km of 24.5 mm (radius) stainless steel pipe. The bunch that passes through the pipe is extremely short with an rms of 8 um for the nominal 100 pC case. Thus, even though the pipe has a large aperture, the wake that applies is the short-range resistive wall wakefield. It turns out that the wake supplies needed dechirping to the LCLS-II beam before it enters the undulator. The LCLS-II bunch distribution is approximately uniform, and therefore the wake induced voltage is characterized by a rather linear voltage chirp for short bunches. However for bunches longer than 25 um (300 pC at 1 kA) the wake starts to become nonlinear, effectively limiting the maximum charge with which the LCLS-II can operate. In this note we calculate the wake, discuss the confidence in the calculation, and investigate how to improve the induced chirp linearity and/or strength. Finally, we also study the strength and effects of the transverse (dipole) resistive wall wakefield.

TUPP133	Optimization of the RF Cavity of the Medical Purpose Electron Linac by Using Genetic Algorithm	cavity, electron, linac, acceleration	726
	S. Shin, J.-S. Chai SKKU, Suwon, Republic of Korea
	A compact electron linear accelerator for the medical application has been developing at Sungkyunkwan University. Due to this electron linac is attached on the robot arm or gantry, it should be compact enough to be held by the structure. An X-band technology has been used to meet the requirements for the compact linac. Because the particle accelerator is complex and sensitive machine to design it takes a lot of time to get a good performance accelerator. In this research, a special technique named single-objective genetic algorithm for the optimization process has been applied to achieve a better RF cavity design by changing various geometric parameters.

TUPP137	High Power Solid-State Amplifiers. New Developments and Technology Comparison	controls, operation, vacuum, power-supply	733
	G.B. Sharkov, A.I. Botyachkova, E.V. Ivanov, N.G. Kalugin, A.A. Krasnov, K.K. Naraianamurtkhi, K.I. Nikolskiy, S.A. Polikhov, I. Řežanov, A.Yu. Smirnov, P. Yazev Siemens Research Center, Moscow,, Russia A.I. Botyachkova National Research Nuclear University (MEPhI), Moscow, Russia
	Funding: Skolkovo Foundation, contract #44 from 2011.11.14 We present a newly developed compact and cost effective SSPA with megawatt range output power and scalable architecture. System components test results are discussed. A comparison of the state-of-the-art vacuum tube and solid-state technologies of RF power amplifiers for scientific accelerators is given. Solid-state microwave generator, Siemens

THPP004	Design, Development and Initial Results of Solid State Magnetron Modulator	distributed, klystron, induction, electron	843
	A.R. Tillu, S. Chandan, K.P. Dixit, K.C. Mittal, H.E. Sarukte BARC, Mumbai, India
	A prototype solid state pulse modulator based on Induction Adder Topology has been designed ans is currently being tested on a S Band Pulsed magnetron rated for 3.2M W Peak RF Power. After successful lab tests the modulator is intended for use in cargo scanning and radiography applications. Currently the topology consists of 4 no.s of single turn primaries driven independently at voltages not more than 1000V. The secondary encircles all the four primaries to generate the desired pulsed voltage across the magnetron. The designed output pulse parameters are 50k V, 120A, 4micro s, at a pulse repetition rate of 250 pps. The paper describes the design and development of the Epoxy Cast Pulse transformer and the Low Inductance Primary Circuit. The rise time measured was < 400ns, and the reverse voltage at the end of the pulse was less than 12kV (at 43k V pulse). The testing was done at low PRF, on two different magnetrons having different operating points to demonstrate fairly good impedance independent operating characteristic of the magnetron modulator. Initial test results on the Resistive load and Magnetron load will also be discussed
	Poster THPP004 [1.575 MB]

THPP013	Prototype Development of the CLIC Crab Cavities	cavity, dipole, damping, simulation	856
	G. Burt, P.K. Ambattu, A.C. Dexter, M. Jenkins, C. Lingwood, B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom V.A. Dolgashev SLAC, Menlo Park, California, USA P. Goudket, P.A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A. Grudiev, G. Riddone, A. Solodko, I. Syratchev, R. Wegner, W. Wuensch CERN, Geneva, Switzerland C. Hill, N. Templeton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	CLIC will require two crab cavities to align the beams to provide an effective head-on collision with a 20 mdeg crossing angle at the interaction point. An X-band system has been chosen for the crab cavities. Three prototype cavities have been developed in order to test the high power characteristics of these cavities. One cavity has been made by UK industry and one has been made using the same process as the CLIC main linac in order to gain understanding of breakdown behaviour in X-band deflecting cavities. The final cavity incorporates mode-damping waveguides on each cell which will eventually contain SiC dampers. This paper details the design, manufacture and preparation of these cavities for testing and a report on their status.

THPP051	Design of a Quasi-Waveguide Multicell Deflecting Cavity for the Advanced Photon Source	cavity, HOM, dipole, damping	966
	A. Lunin, I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev Fermilab, Batavia, Illinois, USA A. Zholents ANL, Argonne, Ilinois, USA
	This paper reports the electromagnetic design of a 2815 MHz Quasi-waveguide Multicell Resonator (called QMiR) being considered as a transverse RF deflecting cavity for the Advanced Photon Source’s (APS) Short Pulse X-ray project. QMiR forms a trapped dipole mode inside a beam vacuum chamber while High Order Modes (HOM) are heavily loaded. It results a sparse HOM spectrum, makes HOM couplers unnecessary and allows to simplify the cavity mechanical design. The form of electrodes is optimized for producing 2 MV of deflecting voltage and keeping low peak surface electric and magnetic fields of 54 MV/m and 75 mT respectively. Results of detailed EM analysis, including HOM damping at the actual geometry of beam vacuum chamber, will be presented.
	Poster THPP051 [1.250 MB]

THPP061	RF Design of a Novel S-Band Backward Traveling Wave Linac for Proton Therapy	coupling, linac, accelerating-gradient, proton	992
	S. Benedetti, U. Amaldi TERA, Novara, Italy A. Degiovanni, A. Grudiev, W. Wuensch CERN, Geneva, Switzerland
	Proton therapy is a rapidly developing technique for tumour treatment, thanks to the physical and dosimetric advantages of charged particles in the dose distribution. Here the RF design of a novel high gradient accelerating structure for proton Linacs is discussed. The choice of a linear accelerator lies mainly in its advantage over cyclotron and synchrotron in terms of fast energy modulation of the beam, which allows the implementation of active spot scanning technique without need of passive absorbers. The design discussed hereafter represents a unicum thanks to the accelerating mode chosen, a 2.9985 GHz backward traveling wave mode with 150° phase advance, and to the RF design approach. The prototype has been designed to reach an accelerating gradient of 50 MV/m, which is more than twice that obtained before. This would allow a shorter Linac potentially reducing cost. The complete 3D RF design of the full structure for beta equal to 0.38 is presented. A prototype will be soon produced and tested at high power. This structure is part of the TULIP project, a proton therapy single-room facility based on high gradient linear accelerators.
	Slides THPP061 [1.537 MB]

THPP069	Status and Outlook of the 325 MHz 4-Rod RFQ	rfq, dipole, simulation, HOM	1010
	B. Koubek, H. Podlech, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany
	In order to built a Radio Frequency Quadrupole (RFQ) at 325 MHz for the FAIR proton linac, a 4-rod structure has been investigated. The RF design, especially the dipole and fringe fields and higher order modes, has been studied with simulations. A prototype has been built and power tested to verify the simulation results and investigate the high power performance. This paper summarizes the results of the research concerning the 325 MHz 4-rod RFQ and gives an overview about the next steps in this project.

THPP092	Development of Slow Neutron Accelerator for Rebunching Pulsed Neutrons	neutron, experiment, resonance, acceleration	1062
	S. Imajo Kyoto University, Kyoto, Japan Y. Fuwa, Y. Iwashita, R. Kitahara Kyoto ICR, Uji, Kyoto, Japan T. Ino KEK, Ibaraki, Japan M. Kitaguchi, H.M. Shimizu Nagoya University, Nagoya, Japan K. Mishima ICEPP, Tokyo, Japan
	Low energy neutrons can be accelerated or decelerated by the technique of AFP-NMR with RF and gradient magnetic fields. The neutrons have magnetic moments, hence their potential energy are not cancelled before and after passage of magnetic fields and their kinetic energy change finally when their spins are flipped in the fields. Nowadays most measurements of the neutron electric dipole moment (nEDM) are carried out with ultra cold neutrons (UCN), whose kinetic energies are lower than about 300 neV, and with a small storage bottle to reduce the systematic errors. In such experiments highly dense UCNs are desired. The spallation neutron sources generate high-density neutrons, however, the pulsed neutrons with several velocities are diffused in guide tubes under long beam intervals. It is necessary to focus and rebunch UCN temporally upon the bottle by controlling their velocities in nEDM experiments at those facilities. We demonstrated such rebuncher and have been developed the advanced apparatus which makes it possible to handle broader energy range UCN. The design, measured characteristics, the experimental setup and the obtained results at J-PARC will be described.

THPP104	Simulation of the Electron Beam Dynamics in the Biperiodical Structure	electron, simulation, coupling, Windows	1096
	Yu.D. Kliuchevskaia, T.V. Bondarenko, S.M. Polozov MEPhI, Moscow, Russia
	А biperiodical accelerating structure (BAS) with operating frequency 27 GHz for the 6 MeV compact radiotherapy electron accelerator is considered. The operating frequency 27 GHz allows to significantly reduce the facility sizes, unlike the S-, X- and C-band operating linacs. The optimal geometrical parameters of BAS necessary for π/2 mode were defined by means of accelerating and coupling cell tuning. The BAS coupler was also simulated. Results of the electron beam dynamics analysis in designed structure are also discussed.

THPP120	Status of Radio-Frequency (RF) Deflectors at Radiabeam	electron, cavity, simulation, laser	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.

THPP125	Super-Compact SLED System Used in the LCLS Diagnostic System	cavity, electron, coupling, klystron	1151
	J.W. Wang, S.G. Tantawi, C. Xu SLAC, Menlo Park, California, USA
	Funding: * Work supported by Department of Energy contract DE–AC03–76SF00515. At SLAC, we have designed and installed an X-band radio-frequency transverse deflector system at the LCLS for measurement of the time-resolved lasing effects on the electron beam and extraction of the temporal profile of the pulses in routine operations. We have designed an X-Band SLED system capable design to augment the available klystron power and to double the kick.

Paper

Title

Other Keywords

Page

MOPP020

Input Couplers for Cornell ERL

linac, cryomodule, coupling, cavity

95

R.G. Eichhorn, P. Quigley, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.A. Belomestnykh
BNL, Upton, Long Island, New York, USA

Cornell has developed two types of input couplers for the Energy Recovery Linac (ERL) Project. Both couplers are 1.3 GHz CW coaxial couplers. The coupler for ERL injector is a 65 kW CW coupler with variable coupling (Qext = 9*E4 to 9*E5). The coupler for ERL main linac is a 5 kW CW coupler with fixed coupling. It can be easily modified for variable coupling operation. Couplers have been tested on test stands and in cryomodules and showed good performance.

MOPP028

New Criterion for Shape Optimization of Normal-Conducting Accelerator Cells for High-Gradient Applications

factory, database, resonance, simulation

114

K.N. Sjobak, A. Grudiev
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway

When optimizing the shape of high-gradient accelerating cells, the goal has traditionally been to minimize the peak surface electric field / gradient, or more recently minimizing the peak modified Poynting vector / gradient squared. This paper presents a method for directly comparing these quan- tities, as well as the power flow per circumference / gradient squared. The method works by comparing the maximum tolerable gradient at a fixed pulse length and breakdown rate that can be expected from the different constraints. The paper also presents a set of 120° phase-advance cells for traveling wave structures, which were designed for the new CLIC main linac accelerating structure, and which are optimized according to these criteria.

MOPP118

C-Band Load Development for the High Power Test of the SwissFEL RF Pulse Compressor

cavity, klystron, vacuum, coupling

329

A. Citterio, J. Stettler, R. Zennaro
PSI, Villigen PSI, Switzerland

The SwissFEL C-band Linac will have 26 RF modules, each one consisting of a solid-state modulator and a 50 MW klystron that feeds a pulse compressor and four two meters long accelerating structures. The pulse compressor is of the Barrel Open Cavity type (BOC). A first prototype was successfully produced and high-power tested, reaching for full power klystron operation a peak power of 300 MW. For testing this BOC at maximum RF power, a broadband load was designed and built, based on a ridge waveguide design and high permeability stainless steel. Based on the experience gained at CERN for CLIC X-band high power loads, the RF design of the load was optimized to ensure high losses for a quite large range of magnetic steels. Test pieces were realized in three different magnetic steels to choose the best suited material commercially available. This paper reports about the RF design, material study, production and impressive high power results of this C-band load.

MOPP122

Construction of the New Amplifiers for the RIKEN-LINAC

ion, heavy-ion, cathode, controls

339

K. Suda, E. Ikezawa, O. Kamigaito, N. Sakamoto, K. Yamada
RIKEN Nishina Center, Wako, Japan
Y. Touchi
SHI, Tokyo, Japan

New tetrode based amplifiers have been constructed for the RIKEN heavy-ion linac, so called RILAC[1], replacing 36-year-old amplifiers to improve their reliability as a main injector for the RIBF accelerator complex. The RILAC is a DC machine and their frequency are tunable between 18 to 40 MHz so as to be capable of accelerating heavy ions with mass-to-charge (m/q) ratios up to 28. The new rf amplifier is based on a tetrode THALES/SIEMENS RS2042SK coupled with a tetrode THALES/SIEMENS RS2012CJ with a grounded grid circuit. The maximum output power is 100 kW with a frequency ranging from 18 to 40 MHz. The amplifier was originally designed for RIKEN Ring Cyclotron. Since we have many experiences with this type of amplifier, some modification to avoid exciting the parasitic modes which might damage the cavity and/or the amplifier itself. Their construction started in April 2013 and installation was performed in January 2014. After the installation their commissioning has been successfully made. For a beam service started in this March the new amplifiers were operated without any troubles. [1]M. Odera et al., Nucl. Instrum. and Methods, 227, 187(1984).

Poster MOPP122 [16.391 MB]

MOPP125

Comparison of Normal Conducting High Energy Accelerating Structures for a Moderate Operating Frequency

coupling, linac, Windows, proton

348

V.V. Paramonov
RAS/INR, Moscow, Russia

The progress in the CERN Linac 4 project confirms the very attractive possibility for single frequency high intensity high energy normal conducting hadron linac. The important part of such linac is the accelerating structure for high energy part. Parameters of possible accelerating structures, referring to PIMS, at operating frequency 352 MHz are considered for proton energy up to 600 MeV. The set of parameters, such as dimensions, RF efficiency, field stability, cooling capability, vacuum conductivity, are considered and compared.

MOPP126

Untrapped HOM Radiation Absorption in the LCLS-II Cryomodules

HOM, cryomodule, cavity, linac

351

K.L.F. Bane, C. Adolphsen, C.D. Nantista, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
A. Saini, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Department of Energy contract DE–AC02–76SF00515.
The superconducting cavities in the continuous wave (CW) linacs of LCLS-II are designed to operate at 2 K, where cooling costs are very expensive. One source of heat is presented by the higher order mode (HOM) power deposited by the beam. Due to the very short bunch length-especially in L3 the final linac-the LCLS-II beam spectrum extends into the terahertz range. Ceramic absorbers, at 70 K and located between cryomodules, are meant to absorb much of this power. In this report we perform two kinds of calculations to estimate the effectiveness of the absorbers and the amount of beam power that needs to be removed at 2 K.

TUPP007

Multi Gigawatt High Current Pulsed Electron Accelerator Technology Development Program at BARC

electron, linac, high-voltage, induction

456

A. Sharma, R. Agarwal, M. Beg, R. Chandra, H. Choudhary, L.M. Gantayet, S.R. Ghodke, TS. Kolge, R. Kumar, S. Mitra, K.C. Mittal, A.S. Patel, A. Roy, P.C. Saroj, K. Senthil, V.K. Sharma, S.K. Singh
BARC, Mumbai, India

High current intense electron beams were investigated earlier for Flash X-rays and nuclear electromagnetic pulse generation. Starting with moderate parameters of 200 kV, 6 kA, 60 ns pulsed electron beam source from a system named Kilo Ampere Linear Injector (KALI-75) our latest development is KALI-30 GW system rated for 1 MV, 30 kA, 80 ns. First repetitive pulse LINAC without spark gap switching was developed as Linear Induction Accelerator (LIA-200) for technology demonstrations at 100 Hz. Also a repetitive Marx generator coupled reflex triode system to operate at 10 Hz. Next to this series of development LIA-400 has been developed to a capacity of 400 kV, 4 kA, 100 ns, 300 Hz. To make these pulse power systems applicable for big LINAC projects like nToF studies or ADS program, a high current electron gun has also been developed to give 100 A, 2 ns,10 Hz pulses.
References
[1].Amitava Roy et al, Journal of App. Physics 103, 2008.
[2].D. D. P. Kumar, et al. Rev. Sci. Inst., vol. 78, no. 11, 2007.
[3].Archana Sharma, et al., IEEE-PS Vol. 39, No. 5, 2011.

TUPP072

Studies on Wake Field in Annular Coupled Structure

wakefield, cavity, linac, acceleration

593

Y. Liu, T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
K. Futatsukawa
KEK, Ibaraki, Japan
A. Miura
JAEA/J-PARC, Tokai-mura, Japan

LINAC injector of J-PARC (Japan Proton Accelerator Research Complex) was recently successfully upgraded from 181 MeV to 400 MeV, applying a type of coupled cavity linac (CCL) structure ACS (Annular Coupled Structure). It was warmly discussed since very beginning on the wake field in the ACS cavities, where there are CCL modes with the same number as that of cells within ~50 MHz, possibly resonating with high intensity proton/H⁻ beams. One of the most important effects from the wake field is the influence on the ACS phase scan. Analytical and simulation studies, as well as the countermeasures were prepared before the energy upgrade. Fortunately we found that detuning of the ACS was unnecessary, which helped to save much work in the commissioning. In addition we got chance to make experiment studies. It was also discussed why the wake field is not so serious as we expected at the very beginning.

TUPP108

HOM and Impedance Study of RF Separators for LCLS II

cavity, HOM, dipole, superconducting-RF

674

S.U. De Silva, J.R. Delayen, B.R.P. Gamage, G.A. Krafft, T. Satogata
ODU, Norfolk, Virginia, USA
R.G. Olave
Old Dominion University, Norfolk, Virginia, USA

The LCLS-II upgrade requires an rf spreader system to guide bunches into a switchyard delivering beam to two undulators and the primary beam dump. The beam pattern therefore needs a 3-way beam spreader. An rf deflecting cavity concept was proposed that includes both superconducting and normal conducting options. We characterize the higher order modes (HOM) of these rf separator cavities and evaluate beam dynamics effects due to potential HOM excitation. This study includes both short term wake and multi-bunch effects.

Poster TUPP108 [1.032 MB]

TUPP113

High RF Power Test of Coupled RFQ-SFRFQ Cavity

cavity, rfq, simulation, detector

689

W.L. Xia, J.E. Chen, S.L. Gao, F.J. Jia, Y.R. Lu, Z. Wang, J. Zhao, K. Zhu
PKU, Beijing, People's Republic of China

Funding: This work was supported in part by the National Natural Science Foundation of China under Grant No. 11075008, 11079001 and 11175009.
A new combined accelerator that couples radio frequency quadrupole (RFQ) and separated function radio frequency quadrupole (SFRFQ) in a single cavity has been designed and manufactured. Recently, the performance of the cavity under high RF power was tested with an upgraded RF power source. The inter-vane voltages of both RFQ section and SFRFQ section were measured by using high purity germanium detector and the corresponding measurement system. The measured shunt impedance is about 546.9 kΩ•m, which means the cavity needs 19.5 kW for the designed inter-vane voltage of 65 kV. The results are well consistent with the cavity design.

Poster TUPP113 [0.764 MB]

TUPP122

Roughness Tolerances in the Undulator Vacuum Chamber of LCLS-II

undulator, vacuum, wakefield, FEL

708

K.L.F. Bane, G.V. Stupakov
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE–AC02–76SF00515.
In LCLS-II, after acceleration and compression and just before entering the undulator, the beam passes through roughly 2.5 km of 24.5 mm (radius) stainless steel pipe. The bunch that passes through the pipe is extremely short with an rms of 8 um for the nominal 100 pC case. Thus, even though the pipe has a large aperture, the wake that applies is the short-range resistive wall wakefield. It turns out that the wake supplies needed dechirping to the LCLS-II beam before it enters the undulator. The LCLS-II bunch distribution is approximately uniform, and therefore the wake induced voltage is characterized by a rather linear voltage chirp for short bunches. However for bunches longer than 25 um (300 pC at 1 kA) the wake starts to become nonlinear, effectively limiting the maximum charge with which the LCLS-II can operate. In this note we calculate the wake, discuss the confidence in the calculation, and investigate how to improve the induced chirp linearity and/or strength. Finally, we also study the strength and effects of the transverse (dipole) resistive wall wakefield.

TUPP133

Optimization of the RF Cavity of the Medical Purpose Electron Linac by Using Genetic Algorithm

cavity, electron, linac, acceleration

726

S. Shin, J.-S. Chai
SKKU, Suwon, Republic of Korea

A compact electron linear accelerator for the medical application has been developing at Sungkyunkwan University. Due to this electron linac is attached on the robot arm or gantry, it should be compact enough to be held by the structure. An X-band technology has been used to meet the requirements for the compact linac. Because the particle accelerator is complex and sensitive machine to design it takes a lot of time to get a good performance accelerator. In this research, a special technique named single-objective genetic algorithm for the optimization process has been applied to achieve a better RF cavity design by changing various geometric parameters.

TUPP137

High Power Solid-State Amplifiers. New Developments and Technology Comparison

controls, operation, vacuum, power-supply

733

G.B. Sharkov, A.I. Botyachkova, E.V. Ivanov, N.G. Kalugin, A.A. Krasnov, K.K. Naraianamurtkhi, K.I. Nikolskiy, S.A. Polikhov, I. Řežanov, A.Yu. Smirnov, P. Yazev
Siemens Research Center, Moscow,, Russia
A.I. Botyachkova
National Research Nuclear University (MEPhI), Moscow, Russia

Funding: Skolkovo Foundation, contract #44 from 2011.11.14
We present a newly developed compact and cost effective SSPA with megawatt range output power and scalable architecture. System components test results are discussed. A comparison of the state-of-the-art vacuum tube and solid-state technologies of RF power amplifiers for scientific accelerators is given.
Solid-state microwave generator, Siemens

THPP004

Design, Development and Initial Results of Solid State Magnetron Modulator

distributed, klystron, induction, electron

843

A.R. Tillu, S. Chandan, K.P. Dixit, K.C. Mittal, H.E. Sarukte
BARC, Mumbai, India

A prototype solid state pulse modulator based on Induction Adder Topology has been designed ans is currently being tested on a S Band Pulsed magnetron rated for 3.2M W Peak RF Power. After successful lab tests the modulator is intended for use in cargo scanning and radiography applications. Currently the topology consists of 4 no.s of single turn primaries driven independently at voltages not more than 1000V. The secondary encircles all the four primaries to generate the desired pulsed voltage across the magnetron. The designed output pulse parameters are 50k V, 120A, 4micro s, at a pulse repetition rate of 250 pps. The paper describes the design and development of the Epoxy Cast Pulse transformer and the Low Inductance Primary Circuit. The rise time measured was < 400ns, and the reverse voltage at the end of the pulse was less than 12kV (at 43k V pulse). The testing was done at low PRF, on two different magnetrons having different operating points to demonstrate fairly good impedance independent operating characteristic of the magnetron modulator. Initial test results on the Resistive load and Magnetron load will also be discussed

Poster THPP004 [1.575 MB]

THPP013

Prototype Development of the CLIC Crab Cavities

cavity, dipole, damping, simulation

856

G. Burt, P.K. Ambattu, A.C. Dexter, M. Jenkins, C. Lingwood, B.J. Woolley
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
V.A. Dolgashev
SLAC, Menlo Park, California, USA
P. Goudket, P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Grudiev, G. Riddone, A. Solodko, I. Syratchev, R. Wegner, W. Wuensch
CERN, Geneva, Switzerland
C. Hill, N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

CLIC will require two crab cavities to align the beams to provide an effective head-on collision with a 20 mdeg crossing angle at the interaction point. An X-band system has been chosen for the crab cavities. Three prototype cavities have been developed in order to test the high power characteristics of these cavities. One cavity has been made by UK industry and one has been made using the same process as the CLIC main linac in order to gain understanding of breakdown behaviour in X-band deflecting cavities. The final cavity incorporates mode-damping waveguides on each cell which will eventually contain SiC dampers. This paper details the design, manufacture and preparation of these cavities for testing and a report on their status.

THPP051

Design of a Quasi-Waveguide Multicell Deflecting Cavity for the Advanced Photon Source

cavity, HOM, dipole, damping

966

A. Lunin, I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
A. Zholents
ANL, Argonne, Ilinois, USA

This paper reports the electromagnetic design of a 2815 MHz Quasi-waveguide Multicell Resonator (called QMiR) being considered as a transverse RF deflecting cavity for the Advanced Photon Source’s (APS) Short Pulse X-ray project. QMiR forms a trapped dipole mode inside a beam vacuum chamber while High Order Modes (HOM) are heavily loaded. It results a sparse HOM spectrum, makes HOM couplers unnecessary and allows to simplify the cavity mechanical design. The form of electrodes is optimized for producing 2 MV of deflecting voltage and keeping low peak surface electric and magnetic fields of 54 MV/m and 75 mT respectively. Results of detailed EM analysis, including HOM damping at the actual geometry of beam vacuum chamber, will be presented.

Poster THPP051 [1.250 MB]

THPP061

RF Design of a Novel S-Band Backward Traveling Wave Linac for Proton Therapy

coupling, linac, accelerating-gradient, proton

992

S. Benedetti, U. Amaldi
TERA, Novara, Italy
A. Degiovanni, A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland

Proton therapy is a rapidly developing technique for tumour treatment, thanks to the physical and dosimetric advantages of charged particles in the dose distribution. Here the RF design of a novel high gradient accelerating structure for proton Linacs is discussed. The choice of a linear accelerator lies mainly in its advantage over cyclotron and synchrotron in terms of fast energy modulation of the beam, which allows the implementation of active spot scanning technique without need of passive absorbers. The design discussed hereafter represents a unicum thanks to the accelerating mode chosen, a 2.9985 GHz backward traveling wave mode with 150° phase advance, and to the RF design approach. The prototype has been designed to reach an accelerating gradient of 50 MV/m, which is more than twice that obtained before. This would allow a shorter Linac potentially reducing cost. The complete 3D RF design of the full structure for beta equal to 0.38 is presented. A prototype will be soon produced and tested at high power. This structure is part of the TULIP project, a proton therapy single-room facility based on high gradient linear accelerators.

Slides THPP061 [1.537 MB]

THPP069

Status and Outlook of the 325 MHz 4-Rod RFQ

rfq, dipole, simulation, HOM

1010

B. Koubek, H. Podlech, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany

In order to built a Radio Frequency Quadrupole (RFQ) at 325 MHz for the FAIR proton linac, a 4-rod structure has been investigated. The RF design, especially the dipole and fringe fields and higher order modes, has been studied with simulations. A prototype has been built and power tested to verify the simulation results and investigate the high power performance. This paper summarizes the results of the research concerning the 325 MHz 4-rod RFQ and gives an overview about the next steps in this project.

THPP092

Development of Slow Neutron Accelerator for Rebunching Pulsed Neutrons

neutron, experiment, resonance, acceleration

1062

S. Imajo
Kyoto University, Kyoto, Japan
Y. Fuwa, Y. Iwashita, R. Kitahara
Kyoto ICR, Uji, Kyoto, Japan
T. Ino
KEK, Ibaraki, Japan
M. Kitaguchi, H.M. Shimizu
Nagoya University, Nagoya, Japan
K. Mishima
ICEPP, Tokyo, Japan

Low energy neutrons can be accelerated or decelerated by the technique of AFP-NMR with RF and gradient magnetic fields. The neutrons have magnetic moments, hence their potential energy are not cancelled before and after passage of magnetic fields and their kinetic energy change finally when their spins are flipped in the fields. Nowadays most measurements of the neutron electric dipole moment (nEDM) are carried out with ultra cold neutrons (UCN), whose kinetic energies are lower than about 300 neV, and with a small storage bottle to reduce the systematic errors. In such experiments highly dense UCNs are desired. The spallation neutron sources generate high-density neutrons, however, the pulsed neutrons with several velocities are diffused in guide tubes under long beam intervals. It is necessary to focus and rebunch UCN temporally upon the bottle by controlling their velocities in nEDM experiments at those facilities. We demonstrated such rebuncher and have been developed the advanced apparatus which makes it possible to handle broader energy range UCN. The design, measured characteristics, the experimental setup and the obtained results at J-PARC will be described.

THPP104

Simulation of the Electron Beam Dynamics in the Biperiodical Structure

electron, simulation, coupling, Windows

1096

Yu.D. Kliuchevskaia, T.V. Bondarenko, S.M. Polozov
MEPhI, Moscow, Russia

А biperiodical accelerating structure (BAS) with operating frequency 27 GHz for the 6 MeV compact radiotherapy electron accelerator is considered. The operating frequency 27 GHz allows to significantly reduce the facility sizes, unlike the S-, X- and C-band operating linacs. The optimal geometrical parameters of BAS necessary for π/2 mode were defined by means of accelerating and coupling cell tuning. The BAS coupler was also simulated. Results of the electron beam dynamics analysis in designed structure are also discussed.

THPP120

Status of Radio-Frequency (RF) Deflectors at Radiabeam

electron, cavity, simulation, laser

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.

THPP125

Super-Compact SLED System Used in the LCLS Diagnostic System

cavity, electron, coupling, klystron

1151

J.W. Wang, S.G. Tantawi, C. Xu
SLAC, Menlo Park, California, USA

Funding: * Work supported by Department of Energy contract DE–AC03–76SF00515.
At SLAC, we have designed and installed an X-band radio-frequency transverse deflector system at the LCLS for measurement of the time-resolved lasing effects on the electron beam and extraction of the temporal profile of the pulses in routine operations. We have designed an X-Band SLED system capable design to augment the available klystron power and to double the kick.