RuPAC2016 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
TUCAMH02	CW 100 mA Electron RF Gun for Novosibirsk ERL FEL	gun, cathode, radiation, electron	24
	V. Volkov, V.S. Arbuzov, E. Kenzhebulatov, E.I. Kolobanov, A.A. Kondakov, E.V. Kozyrev, S.A. Krutikhin, I.V. Kuptsov, G.Y. Kurkin, S.V. Motygin, A.A. Murasev, V.K. Ovchar, V.M. Petrov, A.M. Pilan, A.V. Repkov, M.A. Scheglov, I.K. Sedlyarov, S.S. Serednyakov, O.A. Shevchenko, S.V. Tararyshkin, A.G. Tribendis, N.A. Vinokurov BINP SB RAS, Novosibirsk, Russia N.A. Vinokurov NSU, Novosibirsk, Russia
	Funding: Grant 14-50-00080 of the Russian Science Foundation Continuous wave (CW) 100 mA electron RF gun for injecting the high-quality 300-400 keV electron beam in Novosibirsk microtron recuperator (ERL) and driving Free Electron Laser (FEL) was developed, built, and commissioned at BINP SB RAS. The RF gun consists of normal conducting 90 MHz RF cavity with a gridded thermionic cathode unit. Bench tests of rf gun is confirmed good results in strict accordance with the calculations. The gun was tested up to the design specifications at a test bench that includes a diagnostics beam line. The rf gun stand testing showed reliable work, unpretentious for vacuum conditions and stable in long-term operation. The design features of different components of the gun are presented. Preparation and commissioning experience is discussed. The beam test results are summarized.
	Slides TUCAMH02 [2.764 MB]
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TUZMH02	INR High Intensity Proton Linac. Status and Prospects.	linac, proton, operation, neutron	48
	A. Feschenko, L.V. Kravchuk, V.L. Serov RAS/INR, Moscow, Russia
	The status and the prospects of High Intensity INR Linac are presented. The routine beam intensity is equal to 130 mkA. The annual accelerator run duration is about 1600 hours. The main beam user facilities are multipurpose complex for neutron science, isotope production facility and proton therapy facility. The primary activities are accelerator maintenance, modernization of accelerator systems and beam transportation channels, increasing of accelerator reliability, improvement of beam parameters.
	Slides TUZMH02 [7.267 MB]
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WECBMH01	First Cold Tests of the Superconducting cw Demonstrator at GSI	linac, ion, electron, cryomodule	83
	F.D. Dziuba, M. Amberg, K. Aulenbacher, W.A. Barth, V. Gettmann, M. Miski-Oglu HIM, Mainz, Germany M. Amberg, M. Basten, M. Busch, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany K. Aulenbacher IKP, Mainz, Germany W.A. Barth, M. Heilmann, S. Mickat, S. Yaramyshev GSI, Darmstadt, Germany W.A. Barth, S. Yaramyshev MEPhI, Moscow, Russia
	The future experimental program of super heavy element synthesis at GSI desires high intense heavy ion beams at or above the coulomb barrier, exceeding the capabilities of the GSI-UNILAC (Universal Linear Accelerator). Additionally, the existing GSI accelerator chain will be used as an injector for FAIR (Facility for Antiproton and Ion Research) primarily providing high power heavy ion beams at a low repetition rate. Due to this limitations a new dedicated superconducting (sc) continuous wave (cw) linac is proposed to keep the Super Heavy Element (SHE) research program at GSI competitive. The construction of the first linac section has been finished in the 3rd quarter of 2016. It serves as a prototype to demonstrate its reliable operability in a realistic accelerator environment. This demonstrator cryomodule comprises the sc 217 MHz crossbar-H-mode (CH) multigap cavity as the key component of the whole project and two sc 9.3 T solenoids. The performance of the cavity has been extensively tested at cryogenic temperatures. In this contribution the measurement results of initial cold tests will be presented.
	Slides WECBMH01 [4.677 MB]
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THZMH02	Status of Superconducting ISAC-II and eLinac accelerators, and SRF Activities at TRIUMF	cryomodule, TRIUMF, SRF, ISAC	133
	V. Zvyagintsev, Z.T. Ang, K. Fong, T. Junginger, J.J. Keir, A.N. Koveshnikov, C. Laforge, D. Lang, R.E. Laxdal, Y. Ma, N. Muller, R.R. Nagimov, D.W. Storey, E. Thoeng, B.S. Waraich, Z.Y. Yao, Q. Zheng TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	The development for superconducting accelerators has been started at TRIUMF in 2000. The main milestones and material implementations are: 2006 - commissioning of Phase-I of the heavy ion superconducting accelerator ISAC-II, 2010 - Phase-II, 2014 - commissioning of Phase-I of the superconducting electron linear accelerator eLinac. We are using the accumulated experience and resources for farther SRF development at TRIUMF and external projects VECC, RISP, FRIB and SLAC. TRIUMF is also running fundamental studies for SRF and educational program for universities. Status of Superconducting ISAC-II and eLinac accelerators and SRF development aspects, results and plans are discussed.
	Slides THZMH02 [20.602 MB]
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TUCASH06	Progress in CW Mode Electron Resonance Accelerator BETA-8 Development	electron, resonance, operation, power-supply	185
	A.V. Telnov VNIIEF, Sarov, Russia
	This paper presents the status of powerful linear electron accelerator BETA-8 development. The accelerator is operating in CW mode and used for ionizing radiation research. The basic constituent of accelerator is coaxial half-wave resonator excited on T1 wave. Required electron beam energy is attained by multiple passing through central transversal plane of resonator. Electron beam iterative passing is realized by turning magnets located on resonator outwalls. The main parameters of the accelerator are: beam output energy 1.5 - 7.5 MeV, average power up to 300 kW, operating frequency 100 MHz. By now the main components of facility, namely, coaxial resonator, three HF generator units each with output power 180 kW, HF power summation device, the unit of power input (UPI) designed to transfer HF signal of 600 kW have been designed and manufactured. Electron beam transport system project consisting of up to five full sequential passes through accelerating resonator has been developed. Turning electromagnets have been designed and manufactured. HF parameters measurements for coaxial resonator assembled with UPI have been realized at low HF power level. All HF generator units and HF power summation devices have been tested. HF electron injector has been designed, manufactured and tested. The accelerator testing is supposed to be carried out in one HF generator unit supply mode.
	Slides TUCASH06 [2.798 MB]
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TUCASH07	HF Structure of BETA-8 Electron Resonance Accelerator	electron, resonance, feedback, coupling	188
	M.L. Smetanin VNIIEF, Sarov, Russia
	BETA-8 is new powerful resonance electron accelerator designed in RFNC-VNIIEF to operate in continuous wave generating regime. The basic constituent of accelerator is half-wave coaxial resonator excited at T1 wave. The work presents the main approaches to numerical modeling of accelerator HF power system components. The results of computation of accelerating resonator with operating frequency of 100 MHz and inductive unit of HF power input (UPI) designed to transmit continuous HF signal at operating frequency with mean power level of 600 kW are reported. The transmitting coaxial waveguide connecting UPI with feeding HF generator has been computed, designed and manufactured. The calculated results have been tested by measurements of HF parameters of the resonator assembled with UPI and connecting waveguide. The possibility to locate indicating loop (a detector working in frequency feedback circuit of feeding HF generator) in transmitting feeder has been demonstrated. The method of calibration computation of measuring inductive loop that is an element of amplitude feedback circuit of HF generator is presented. The dual matched load necessary for preliminary adjustment of operating modes of feeding HF generator unit (with mean power up to 180 kW) and technological systems of accelerating complex has been computed, designed and put into operation.
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THXSH01	Development of the INR Linear Accelerator DTL RF System	vacuum, operation, DTL, rf-amplifier	191
	A.I. Kvasha, V.L. Serov RAS/INR, Moscow, Russia A. Feschenko MIPT, Dolgoprudniy, Moscow Region, Russia
	The regular INR DTL RF system operation began in 1992. By this point three new type of vacuum tube, designed purposely for INR linear accelerator, were manufactured at OKB "Swetlana" in the amount sufficient for RF system operation during 20 years. Among them were two vacuum tubes for final RF power amplifier - GI-54A and RF driver - GI-51A and also vacuum tube for powerful anode modulator - GMI-44A. In the late 80s manufacture of these vacuum tubes was stopped and since 1990 designing of new vacuum tube for RF output power amplifier instead of GI-54A was started. The new vacuum tube GI-71A with output RF power up to 3 MW in pulse, plate power dissipation up to 120 kW and power gain about 10 was simpler and less expensive in comparison with GI-54A. The transition to new vacuum tube began in 1999 and finished in 2014. Successful testing of GI-57A as RF driver, fulfilled in 2008, opened the possibility of replacement GI-51A. As for GMI-44A replacement there are no analogues, produced in Russian federation, and, as it turned out, the only option was GI-71A again. Below some problems, connected with the vacuum tubes replacement, as well as main results of twenty years DTL RF system operation are considered.
	Slides THXSH01 [4.748 MB]
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TUPSA004	Proposal of the Accelerating Structure for the First Cavity of the Main Part of INR Linac	linac, coupling, booster, hadron	216
	I.V. Rybakov, A. Feschenko, Y.Z. Kalinin, L.V. Kravchuk, V.N. Leontiev, A.N. Naboka, V.V. Paramonov, V.L. Serov RAS/INR, Moscow, Russia
	For the beam intensity and overall stability improvement of INR linac replacement of the first four section cavity of the main part is required. The present cavity is realized as the Disks and Washers (DAW) structure. The new cavity should not lose to the present one in electro dynamical parameters with minimal modifications in the rest linac systems. As the possible structures for the first cavity replacement both proven in exploitation structures and promising developments were considered. The analysis of electro dynamical parameters, coupled RF heating, mechanical processes and manufacturing analysis were performed for the considered structures. For further development the Cut Disk Structure (CDS) option is proposed as the structure with satisfying RF parameters and having the smallest transverse dimensions in comparison with analogues. For the production simplification with minimal losses in electro dynamical parameters an unification of the main geometrical parameters for the four sections cells was performed. The possibility of multipaction in the cavity is considered and an option for its damping is proposed. The manufacturing tolerances for the structure are estimated.
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TUPSA006	Development of RF Accelerator on Parallel-Coupled Structure - Trend in Accelerator Technique	electron, focusing, coupling, acceleration	219
	Y.D. Chernousov ICKC, Novosibirsk, Russia
	Development of parallel-coupled accelerating structure (PCS), creation of RF linier accelerator based on PCS is new and rapidly developing field of accelerator technology. Compared with conventional accelerating structures with serial communication - the standard traveling and standing waves structures, the PCS has a lot of features and advantages. There are many problems in the development of RF linear accelerators: breakdowns at high power levels, the destruction of the structure due to overheating, the excitation of higher-order mode, the decline of field strength along the structure, transients, beam loading, beam focusing, multipactor, radiation accelerator cleanliness, etc. PCS - the best accelerating structure for solving these problems.
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TUPSA007	New Experimental Results on RF Accelerator with Parallel-Coupled Structure and RF Controlled Gun	injection, electron, gun, focusing	222
	Y.D. Chernousov ICKC, Novosibirsk, Russia I.M. Ikryanov, I.V. Shebolaev ICKC SB RAS, Novosibirsk, Russia
	New data on the development and experimental investigation of the RF accelerator based on the 9-cavities parallel-coupled accelerating structure that is equipped with a high-frequency grid-controlled electron gun are presented. Accelerating structure, injection system and focusing system are improved. Previously observed second emission resonant discharge - multipactor is suppressed by increasing the field amplitude in the structure first cavity and using the protector. The parameters of the accelerated beam close to the design ones, i.e. electron energy up to 8 MeV, capture to the acceleration mode up to 100%, were received. Capture is provided by the RF electron focusing of the microwave field structure with usage of the magnetic focusing system based on permanent magnets and RF grid control in the electron gun.
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TUPSA008	Gradient Limitations for RF Accelerator on Parallel-Coupled Structure	acceleration, accelerating-gradient, linac, vacuum	225
	Y.D. Chernousov ICKC, Novosibirsk, Russia I.V. Shebolaev ICKC SB RAS, Novosibirsk, Russia
	RF breakdown is the main gradient limitation for RF accelerator. It is believed that all the known ways to increase the accelerating gradient have been already investigated. These are increase in the frequency of the accelerating field, reduction in the pulse duration, the optimization of cavities form, selection of operating surface materials, preparation and training of accelerating structures. In this paper, we discuss the possibility of increasing the accelerating gradient due to the circuit design, i.e., the use of the parallel-coupled accelerating structure.
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TUPSA012	Superconducting Stored Energy RF Linac as Free Electron Laser Driver	electron, FEL, linac, laser	237
	V.G. Kurakin, P.V. Kurakin LPI, Moscow, Russia
	Due to cavity losses in multi pass free electron laser (FEL), generation starts in it from definite threshold of driving electron beam current. Depending on generation wave range the threshold current strikes from fraction of ampere to dozens of amperes. In order to rich laser saturation, from hundreds to thousands electron bunches are required. Simple estimations give the value from units up to tens joules of bunches train energy in order to rich FEL saturation for infrared wave range (approximately 20 - 25 MeV of bunches energy and 3 A of pick current, bunch length being 1 cm). A beam with parameters mentioned might be obtained in rf superconducting linac operating in stored energy mode. The advantage of such approach is simplified linac power supply since dozens watts cw rf generator is required only to rich necessary accelerating voltage. At the same time the energy spread arising from beam loading may be compensated by additional cavities exited at shifted frequencies. In this paper Maxwell equations are used for beam-cavity interaction analysis. The bunch energy loss or the same the voltage induced by radiating bunch is expressed in terms of cavity external parameters. The detailed analysis of beam energy spread compensation is carried out followed by an example showing the reality of FEL schema suggested.
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TUPSA028	QWR resonator Cavities Electrodynamics Simulations for new Nuclotron-NICA Injector	simulation, linac, impedance, acceleration	273
	M. Gusarova, T. Kulevoy, M.V. Lalayan, S.M. Polozov, N.P. Sobenin, D.V. Surkov, S.A. Terekhov, S.E. Toporkov, V. Zvyagintsev MEPhI, Moscow, Russia A.V. Butenko, A.O. Sidorin, G.V. Trubnikov JINR, Dubna, Moscow Region, Russia V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	New linac-injector for Nuclotron-NICA is planned to consist of quarter-wave coaxial cavities (QWR) having velocities of ~0.07c and ~0.12c (beam energy from 5 to 17 MeV). These cavities are to be superconducting and operating at 162 MHz. Current results of the QWR cavities electrodynamics simulations and geometry optimizations are presented.
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TUPSA030	Regulation of the Waveguide Coupling Factor of Standing Wave Linear Accelerator	coupling, resonance, insertion, electron	279
	D.S. Yurov MSU, Moscow, Russia V.I. Shvedunov LEA MSU, Moscow, Russia V.I. Shvedunov SINP MSU, Moscow, Russia
	Regulation of the waveguide coupling factor of standing wave linear accelerator allows to adjust the value of accelerated current, keeping the reflected RF power close to zero. This ensures the most efficient use of RF energy and absence of overvoltage in the waveguide elements. The paper presents studies results for various methods of coupling factors regulation with continuous wave (CW) normal conducting linear accelerator used as an example. The results of calculations and measurements on the mock-up of the accelerating structure are presented.
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TUPSA031	The Cascade Interference Switch Comprising a Transmission Resonator	plasma, simulation, distributed, high-voltage	282
	S.A. Gorev, S.N. Artemenko, V.S. Igumnov TPU, Tomsk, Russia
	The new concept of microwave interference switches is reported. Interference switch is based on series of H-plane T-junctions (cascade switch) in the view of decreasing switched power at Off state and comprises irises in both its own input and output arms. At On state the irises act as a transmission resonator localizing the nodes of the standing wave at the junctions. Such distribution is expected to decrease the plasma losses. It was shown with a simulation that the cascade switch with additional irises increases the efficiency of the active microwave compressors. The simulation was made with CST studio and COMSOL.
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TUPSA035	Estimation of Multipacting in CDS Structure	multipactoring, simulation, electron, coupling	288
	I.V. Rybakov RAS/INR, Moscow, Russia I.I. Isaev DESY Zeuthen, Zeuthen, Germany
	The Cut Disk Structure (CDS) is recommended for replacement of the first cavity of the main part of INR linac. For the cavity work stability there should be no multipactor at operating regime. CDS structure was first set on exploitation at DESY PITZ electron linac. For this cavity according to the analytical estimation multipaction should appear at the operating power level in coupling cells, but it was not approved by the numerical simulation with both accelerating and coupling modes excitation for RF energy transfer along the cavity. The multipactor appears only with the secondaty emission yield (SEY) growth which could happen if the inner surface of the cavity is polluted. The results of multipactor investigation in CDS PITZ were used as reference for the CDS structure for the first cavity of the main part of INR linac. The analytical estimation and numerical simulation of multipactor in CDS INR structure shows the appearance of the discharge in coupling cells with the OFC copper SEY for the operating regime of the cavity. An option for the multipactor damping with the forced excitation of oscillations in coupling cell with voltage higher than upper multipactor limit was considered.
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TUPSA036	Manufacturing Tolerances Estimation for Proton Linac Cavities	coupling, linac, proton, simulation	291
	I.V. Rybakov, V.V. Paramonov, A.K. Skasyrskaya RAS/INR, Moscow, Russia
	The definition of manufacturing tolerances is one of the stages of accelerating structure construction. In case of proton linacs the value of accelerating field homogeneity is a critical parameter. It depends both on cells frequencies perturbations and the coupling coefficient perturbations. These values could be obtained using the numerical simulations of the characteristic electromagnetic oscillations in the cell. There is the method that allows the reduction of the simulations time and to avoid separate simulations for each geometrical parameter of the structure. This method was improved and extended for the pi/2-wave, pi-wave and travelling wave structures. Several examples of the method application, including the structure for the first cavity of the main part of INR linac, are presented.
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TUPSA040	S-Band Choke Mode Cavity for Low Energy Storage Ring	HOM, storage-ring, electron, scattering	300
	L. Ovchinnikova, V.I. Shvedunov SINP MSU, Moscow, Russia A. Ryabov IHEP, Moscow Region, Russia V.I. Shvedunov LEA MSU, Moscow, Russia
	Several variants of a low-energy storage ring for Thomson scattering X-ray source were considered in . The most promising variant "C" of the ring with small dimensions and large dynamic aperture has also large momentum compaction factor, which would lead to too long bunches with RF cavity operating at 714 MHz, so shorter wavelength must be used. In this paper we present results of optimization of S-band double-cells cavity with parasitic mode damping by chokes similar to . Interaction of the bunch circulating in the ring with cavity parasitic modes is simulated. L. Ovchinnikova, V. Shvedunov, A. Mikhailichenko et al.. A comparative study of low energy compact storage rings for a thomson scattering x-ray source. Proc. of IPAC-16, 2016, pp. 3308-3310. ** T. Shintake, The Choke Mode Cavity, Jpn. J. Appl. Phys, Vol. 31,1992, pp. L1567-L1570, No. 1lA
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TUPSA046	Experimental Analysis of Dipole Modes in Elliptical Cavity	simulation, experiment, impedance, dipole	313
	Ya.V. Shashkov, M.V. Lalayan, N.P. Sobenin MEPhI, Moscow, Russia A. Orlov NRNU, Moscow, Russia
	The experimental measurements of transverse shunt impedance for higher order modes TM110 and TE111 for S-band elliptical cavity were carried out. The experiments using dielectric and metallic spheres as perturbing objects and with ring probe were done.
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TUPSA050	Electron Beam Stability in the Energy Recovery Linac for the Lithographic Free Electron Laser	electron, linac, undulator, radiation	319
	Ya.V. Getmanov, O.A. Shevchenko, N.A. Vinokurov BINP SB RAS, Novosibirsk, Russia N.A. Vinokurov NSU, Novosibirsk, Russia
	According to microelectronic production leaders the lithography based on the free electron laser (FEL) could become the main technology for the elements mass production with scale to 5 nm in the nearest future. One of the main problem is the absence of the working FEL with required parameters. The feasibility study of those FEL based on superconducting energy-recovery linac (ERL) was made in Budker INP. The ERL average current is limited by longitudinal and transverse instabilities, caused by interaction between electron beam and its induced fields in the superconducting cavities. The estimations of the threshold currents and ERL parameters were made.
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TUPSA068	Simulation of S-Band RF Gun with RF Beam Control	cathode, gun, controls, electron	345
	A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia M.V. Maltseva NSU, Novosibirsk, Russia
	The design and operation of electron RF gun with RF beam control are described. Results of numerical simulation of electromagnetic fields and beam dynamics are presented. RF gun consists of two resonators operating at E010 mode with 180 degrees phase shift at frequency of 2856 MHz. RF control is carried out via coaxial resonator with grid-cathode capacity. Accordint to result of the simulation, RF gun with RF control allows producing electron bunches with duration of 50 ps, energy of about 3 MeV and the energy spread of about 5%.
	Poster TUPSA068 [0.996 MB]
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TUPSA069	Optimization of an RF Probe Vicinity for RF Gun Cavities	gun, HOM, simulation, quadrupole	348
	V.V. Paramonov RAS/INR, Moscow, Russia
	To provide electron bunches with exceptionally high brightness, RF gun cavity should operate with the extreme electric and magnetic fields. The RF probe is required for the mostly reliable and precise measurements of the RF field phase and amplitude directly from the cavity. The implementation of an RF probe in the cavity design generates a set of coupled problems, which is analyzed and compared for different operating frequencies and different RF pulse length. Both general dependencies and particularities are considered. Some recommendations for practical choice of the RF probe are presented.
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WEPSB013	On Approach for Resonant Frequency Tuning in Drift Tube Structures on the Designing Stage	simulation, controls, target, electron	386
	I. Skudnova, V.V. Altsybeyev Saint Petersburg State University, Saint Petersburg, Russia
	Current research considers the interdigital H-mode linear resonant accelerator with drift tubes mounted inside the cavity. The focus of the study has been on the dependence of resonant frequency on the parameters of the geometry. Since Alternating-Phase-Focusing (APF) type of accelerator is investigated, the efficiency of the operation depends on the synchronization of the charged particle velocity and accelerating field oscillations. Researchers can control it by the variation of longitudinal size of the cells of the structure (periods). On the other hand, the effective performance of the resonant system requires the equality of resonant frequencies of its cells, because it affects the uniformity of accelerating field distribution along the axis. The diversity of cells longitudinal sizes causes the deviation from the particular value of the resonant frequency. This aberration can be eliminated by the adjustment of other geometry parameters: period's length, gap ratio and drift tube diameter. We have conducted the study to analyze the relation between resonant frequency and these values. Using the this dependency we can tune the geometry parameters of each period in the structure. We first create the computer-aided design (CAD) geometry model of the accelerator cavity. Then, using Comsol Multiphysics, the platform for physics-based modeling and simulation, we conduct the calculation of resonant frequencies.
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WEPSB032	Numerical Analysis of Cavity Mode Operation and Electron Beam Dynamics in Lebedev Institute Microtron	microtron, electron, operation, simulation	428
	V.S. Dyubkov, Y.A. Bashmakov, Y. Lozeev MEPhI, Moscow, Russia Y.A. Bashmakov LPI, Moscow, Russia
	Dynamics of electrons in classic microtron is studied. 3D cavity model is developed and electromagnetic field distribution is simulated. Dependence of output beam parameters on microtron operation mode is investigated and discussed.
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WEPSB073	Design Study of the Proton Linac for Radiopharmaceuticals Production	DTL, linac, rfq, focusing	524
	G. Kropachev, A.I. Balabin, T. Kulevoy, D.N. Selesnev, A. Sitnikov ITEP, Moscow, Russia T. Kulevoy MEPhI, Moscow, Russia
	The 8 MeV 200 MHz linac for acceleration of quasi cw 0.2 mA proton beam is under development at ITEP. The linac is designed for radiopharmaceuticals production which will be used in the Positron-Emission Tomography. The linac includes RFQ and DTL sections with 6D-beam matching between them. The DTL section has modular structure and consists of separated individually phased IH-cavities with beam focusing by permanent magnet quadrupoles located between the cavities. This DTL structure provides linac compactness and enables its tuning and commissioning cavity by cavity. Results of beam dynamic simulation and electrodynamics characteristics of linac cavities are presented.
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THPSC055	Electrodynamic Characteristics of RF-Deflector for Bunch Shape Monitor	simulation, electron, impedance, insertion	659
	D.A. Chermoshentsev, A. Feschenko, S.A. Gavrilov RAS/INR, Moscow, Russia D.A. Chermoshentsev MIPT, Dolgoprudniy, Moscow Region, Russia D.A. Chermoshentsev Skoltech, Moscow, Russia
	Bunch shape monitors, based on a transverse RF-scanning of secondary electrons, are used for measurements of particles longitudinal distribution in bunches at different linear ion accelerators. The phase resolution of such monitors depends crucially on accuracy of fabrication and tuning of RF-deflector, thus preliminary simulations of its electrodynamic characteristics are of importance for subsequent commissioning of the monitor. Simulations of some basic operational electrodynamic parameters and results of experimental measurements are presented.
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THPSC060	The Longitudinal Distribution and Bunch Length Measurements at VEPP-2000 Collider	collider, impedance, electron, detector	673
	Yu. A. Rogovsky, E. Perevedentsev, V. Volkov, Yu.M. Zharinov BINP SB RAS, Novosibirsk, Russia
	The paper describes the bunch length measurement system for VEPP-2000 collider, equiped with optical analysers based on LI-602 dissector, which provides permanent measurements of the longitudinal beam profile. Potential well distorsion lengthening was measured at different bunch currents for the energies below 500 MeV. First measurements reveals the presence of microwave instabilty with turbulent emittance growth. The thresholds of these processes was used to estimate the values of reactive part of the longitudinal impedance. Measured energy loss factors was compared with computer simulations for the RF cavity. All results will be discussed and further estimations will be given.
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THPSC067	Coaxial Quarter Wavelength Impedance Converter for Coupling Control of Triode Cavity	impedance, coupling, electron, gun	689
	K. Torgasin, T. Kii, K. Masuda, K. Morita, K. Nagasaki, H. Ohgaki, S. Suphakul, H. Zen Kyoto University, Kyoto, Japan
	A quarter wavelength coaxial cavity has been developed for triode-type thermionic RF gun. The triode-type RF gun is a modification of present 4.5 cell thermionic RF gun of KU-FEL (Kyoto University Free Electron Laser) facility with aim to mitigate the back'bombardment effect. Thereby a coaxial quarter wavelength cavity with cathode material shall be added to the main 4.5 cell accelerating body. The coaxial cavity has the function of pre-buncher to control the injection phase and power of electron bunches into the main accelerating body. Transient tests have demonstrated the quarter wavelength cavity to be undercoupled. However, for operation at high beam loading conditions overcoupled conditions are required. In order to control the coupling we have developed an external air side coaxial quarter wavelength impedance converter. The design of the impedance converter enables operation at high RF power (<20 kV) without changing the cavity geometry. In this work we present our design and performance of quarter wavelength impedance converter as applied to quarter wavelength triode cavity. K. Torgasin et al., Cold Test of the Coaxial Cavity for Thermionic Triode Type RF Gun, in Proc. IPAC, 2013, pp.324-326.
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THPSC073	Development of the Hardware-Software Complex PIRS-5 for Field Measurements in Accelerating Structures	software, hardware, controls, impedance	702
	G.S. Pomogaybo, M.V. Lalayan, S.E. Toporkov MEPhI, Moscow, Russia
	Hardware-software complex "PIRS-5" was developed to make measurements in warm accelerating structures. The idea was to create full-automatic measuring system, which can measure electrical field at the bead position with non-resonant and resonant pull techniques. PIRS-5 has postprocessor, which calculate electrical component from the frequency, reflection or transmission coefficient, shunt and effective shunt impedance. This work describes the construction of this complex, its mathematical part and possible future modifications.
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TUCAMH02

CW 100 mA Electron RF Gun for Novosibirsk ERL FEL

gun, cathode, radiation, electron

24

V. Volkov, V.S. Arbuzov, E. Kenzhebulatov, E.I. Kolobanov, A.A. Kondakov, E.V. Kozyrev, S.A. Krutikhin, I.V. Kuptsov, G.Y. Kurkin, S.V. Motygin, A.A. Murasev, V.K. Ovchar, V.M. Petrov, A.M. Pilan, A.V. Repkov, M.A. Scheglov, I.K. Sedlyarov, S.S. Serednyakov, O.A. Shevchenko, S.V. Tararyshkin, A.G. Tribendis, N.A. Vinokurov
BINP SB RAS, Novosibirsk, Russia
N.A. Vinokurov
NSU, Novosibirsk, Russia

Funding: Grant 14-50-00080 of the Russian Science Foundation
Continuous wave (CW) 100 mA electron RF gun for injecting the high-quality 300-400 keV electron beam in Novosibirsk microtron recuperator (ERL) and driving Free Electron Laser (FEL) was developed, built, and commissioned at BINP SB RAS. The RF gun consists of normal conducting 90 MHz RF cavity with a gridded thermionic cathode unit. Bench tests of rf gun is confirmed good results in strict accordance with the calculations. The gun was tested up to the design specifications at a test bench that includes a diagnostics beam line. The rf gun stand testing showed reliable work, unpretentious for vacuum conditions and stable in long-term operation. The design features of different components of the gun are presented. Preparation and commissioning experience is discussed. The beam test results are summarized.

Slides TUCAMH02 [2.764 MB]

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TUZMH02

INR High Intensity Proton Linac. Status and Prospects.

linac, proton, operation, neutron

48

A. Feschenko, L.V. Kravchuk, V.L. Serov
RAS/INR, Moscow, Russia

The status and the prospects of High Intensity INR Linac are presented. The routine beam intensity is equal to 130 mkA. The annual accelerator run duration is about 1600 hours. The main beam user facilities are multipurpose complex for neutron science, isotope production facility and proton therapy facility. The primary activities are accelerator maintenance, modernization of accelerator systems and beam transportation channels, increasing of accelerator reliability, improvement of beam parameters.

Slides TUZMH02 [7.267 MB]

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WECBMH01

First Cold Tests of the Superconducting cw Demonstrator at GSI

linac, ion, electron, cryomodule

83

F.D. Dziuba, M. Amberg, K. Aulenbacher, W.A. Barth, V. Gettmann, M. Miski-Oglu
HIM, Mainz, Germany
M. Amberg, M. Basten, M. Busch, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany
K. Aulenbacher
IKP, Mainz, Germany
W.A. Barth, M. Heilmann, S. Mickat, S. Yaramyshev
GSI, Darmstadt, Germany
W.A. Barth, S. Yaramyshev
MEPhI, Moscow, Russia

The future experimental program of super heavy element synthesis at GSI desires high intense heavy ion beams at or above the coulomb barrier, exceeding the capabilities of the GSI-UNILAC (Universal Linear Accelerator). Additionally, the existing GSI accelerator chain will be used as an injector for FAIR (Facility for Antiproton and Ion Research) primarily providing high power heavy ion beams at a low repetition rate. Due to this limitations a new dedicated superconducting (sc) continuous wave (cw) linac is proposed to keep the Super Heavy Element (SHE) research program at GSI competitive. The construction of the first linac section has been finished in the 3rd quarter of 2016. It serves as a prototype to demonstrate its reliable operability in a realistic accelerator environment. This demonstrator cryomodule comprises the sc 217 MHz crossbar-H-mode (CH) multigap cavity as the key component of the whole project and two sc 9.3 T solenoids. The performance of the cavity has been extensively tested at cryogenic temperatures. In this contribution the measurement results of initial cold tests will be presented.

Slides WECBMH01 [4.677 MB]

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THZMH02

Status of Superconducting ISAC-II and eLinac accelerators, and SRF Activities at TRIUMF

cryomodule, TRIUMF, SRF, ISAC

133

V. Zvyagintsev, Z.T. Ang, K. Fong, T. Junginger, J.J. Keir, A.N. Koveshnikov, C. Laforge, D. Lang, R.E. Laxdal, Y. Ma, N. Muller, R.R. Nagimov, D.W. Storey, E. Thoeng, B.S. Waraich, Z.Y. Yao, Q. Zheng
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

The development for superconducting accelerators has been started at TRIUMF in 2000. The main milestones and material implementations are: 2006 - commissioning of Phase-I of the heavy ion superconducting accelerator ISAC-II, 2010 - Phase-II, 2014 - commissioning of Phase-I of the superconducting electron linear accelerator eLinac. We are using the accumulated experience and resources for farther SRF development at TRIUMF and external projects VECC, RISP, FRIB and SLAC. TRIUMF is also running fundamental studies for SRF and educational program for universities. Status of Superconducting ISAC-II and eLinac accelerators and SRF development aspects, results and plans are discussed.

Slides THZMH02 [20.602 MB]

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TUCASH06

Progress in CW Mode Electron Resonance Accelerator BETA-8 Development

electron, resonance, operation, power-supply

185

A.V. Telnov
VNIIEF, Sarov, Russia

This paper presents the status of powerful linear electron accelerator BETA-8 development. The accelerator is operating in CW mode and used for ionizing radiation research. The basic constituent of accelerator is coaxial half-wave resonator excited on T1 wave. Required electron beam energy is attained by multiple passing through central transversal plane of resonator. Electron beam iterative passing is realized by turning magnets located on resonator outwalls. The main parameters of the accelerator are: beam output energy 1.5 - 7.5 MeV, average power up to 300 kW, operating frequency 100 MHz. By now the main components of facility, namely, coaxial resonator, three HF generator units each with output power 180 kW, HF power summation device, the unit of power input (UPI) designed to transfer HF signal of 600 kW have been designed and manufactured. Electron beam transport system project consisting of up to five full sequential passes through accelerating resonator has been developed. Turning electromagnets have been designed and manufactured. HF parameters measurements for coaxial resonator assembled with UPI have been realized at low HF power level. All HF generator units and HF power summation devices have been tested. HF electron injector has been designed, manufactured and tested. The accelerator testing is supposed to be carried out in one HF generator unit supply mode.

Slides TUCASH06 [2.798 MB]

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TUCASH07

HF Structure of BETA-8 Electron Resonance Accelerator

electron, resonance, feedback, coupling

188

M.L. Smetanin
VNIIEF, Sarov, Russia

BETA-8 is new powerful resonance electron accelerator designed in RFNC-VNIIEF to operate in continuous wave generating regime. The basic constituent of accelerator is half-wave coaxial resonator excited at T1 wave. The work presents the main approaches to numerical modeling of accelerator HF power system components. The results of computation of accelerating resonator with operating frequency of 100 MHz and inductive unit of HF power input (UPI) designed to transmit continuous HF signal at operating frequency with mean power level of 600 kW are reported. The transmitting coaxial waveguide connecting UPI with feeding HF generator has been computed, designed and manufactured. The calculated results have been tested by measurements of HF parameters of the resonator assembled with UPI and connecting waveguide. The possibility to locate indicating loop (a detector working in frequency feedback circuit of feeding HF generator) in transmitting feeder has been demonstrated. The method of calibration computation of measuring inductive loop that is an element of amplitude feedback circuit of HF generator is presented. The dual matched load necessary for preliminary adjustment of operating modes of feeding HF generator unit (with mean power up to 180 kW) and technological systems of accelerating complex has been computed, designed and put into operation.

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THXSH01

Development of the INR Linear Accelerator DTL RF System

vacuum, operation, DTL, rf-amplifier

191

A.I. Kvasha, V.L. Serov
RAS/INR, Moscow, Russia
A. Feschenko
MIPT, Dolgoprudniy, Moscow Region, Russia

The regular INR DTL RF system operation began in 1992. By this point three new type of vacuum tube, designed purposely for INR linear accelerator, were manufactured at OKB "Swetlana" in the amount sufficient for RF system operation during 20 years. Among them were two vacuum tubes for final RF power amplifier - GI-54A and RF driver - GI-51A and also vacuum tube for powerful anode modulator - GMI-44A. In the late 80s manufacture of these vacuum tubes was stopped and since 1990 designing of new vacuum tube for RF output power amplifier instead of GI-54A was started. The new vacuum tube GI-71A with output RF power up to 3 MW in pulse, plate power dissipation up to 120 kW and power gain about 10 was simpler and less expensive in comparison with GI-54A. The transition to new vacuum tube began in 1999 and finished in 2014. Successful testing of GI-57A as RF driver, fulfilled in 2008, opened the possibility of replacement GI-51A. As for GMI-44A replacement there are no analogues, produced in Russian federation, and, as it turned out, the only option was GI-71A again. Below some problems, connected with the vacuum tubes replacement, as well as main results of twenty years DTL RF system operation are considered.

Slides THXSH01 [4.748 MB]

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TUPSA004

Proposal of the Accelerating Structure for the First Cavity of the Main Part of INR Linac

linac, coupling, booster, hadron

216

I.V. Rybakov, A. Feschenko, Y.Z. Kalinin, L.V. Kravchuk, V.N. Leontiev, A.N. Naboka, V.V. Paramonov, V.L. Serov
RAS/INR, Moscow, Russia

For the beam intensity and overall stability improvement of INR linac replacement of the first four section cavity of the main part is required. The present cavity is realized as the Disks and Washers (DAW) structure. The new cavity should not lose to the present one in electro dynamical parameters with minimal modifications in the rest linac systems. As the possible structures for the first cavity replacement both proven in exploitation structures and promising developments were considered. The analysis of electro dynamical parameters, coupled RF heating, mechanical processes and manufacturing analysis were performed for the considered structures. For further development the Cut Disk Structure (CDS) option is proposed as the structure with satisfying RF parameters and having the smallest transverse dimensions in comparison with analogues. For the production simplification with minimal losses in electro dynamical parameters an unification of the main geometrical parameters for the four sections cells was performed. The possibility of multipaction in the cavity is considered and an option for its damping is proposed. The manufacturing tolerances for the structure are estimated.

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TUPSA006

Development of RF Accelerator on Parallel-Coupled Structure - Trend in Accelerator Technique

electron, focusing, coupling, acceleration

219

Y.D. Chernousov
ICKC, Novosibirsk, Russia

Development of parallel-coupled accelerating structure (PCS), creation of RF linier accelerator based on PCS is new and rapidly developing field of accelerator technology. Compared with conventional accelerating structures with serial communication - the standard traveling and standing waves structures, the PCS has a lot of features and advantages. There are many problems in the development of RF linear accelerators: breakdowns at high power levels, the destruction of the structure due to overheating, the excitation of higher-order mode, the decline of field strength along the structure, transients, beam loading, beam focusing, multipactor, radiation accelerator cleanliness, etc. PCS - the best accelerating structure for solving these problems.

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TUPSA007

New Experimental Results on RF Accelerator with Parallel-Coupled Structure and RF Controlled Gun

injection, electron, gun, focusing

222

Y.D. Chernousov
ICKC, Novosibirsk, Russia
I.M. Ikryanov, I.V. Shebolaev
ICKC SB RAS, Novosibirsk, Russia

New data on the development and experimental investigation of the RF accelerator based on the 9-cavities parallel-coupled accelerating structure that is equipped with a high-frequency grid-controlled electron gun are presented. Accelerating structure, injection system and focusing system are improved. Previously observed second emission resonant discharge - multipactor is suppressed by increasing the field amplitude in the structure first cavity and using the protector. The parameters of the accelerated beam close to the design ones, i.e. electron energy up to 8 MeV, capture to the acceleration mode up to 100%, were received. Capture is provided by the RF electron focusing of the microwave field structure with usage of the magnetic focusing system based on permanent magnets and RF grid control in the electron gun.

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TUPSA008

Gradient Limitations for RF Accelerator on Parallel-Coupled Structure

acceleration, accelerating-gradient, linac, vacuum

225

Y.D. Chernousov
ICKC, Novosibirsk, Russia
I.V. Shebolaev
ICKC SB RAS, Novosibirsk, Russia

RF breakdown is the main gradient limitation for RF accelerator. It is believed that all the known ways to increase the accelerating gradient have been already investigated. These are increase in the frequency of the accelerating field, reduction in the pulse duration, the optimization of cavities form, selection of operating surface materials, preparation and training of accelerating structures. In this paper, we discuss the possibility of increasing the accelerating gradient due to the circuit design, i.e., the use of the parallel-coupled accelerating structure.

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TUPSA012

Superconducting Stored Energy RF Linac as Free Electron Laser Driver

electron, FEL, linac, laser

237

V.G. Kurakin, P.V. Kurakin
LPI, Moscow, Russia

Due to cavity losses in multi pass free electron laser (FEL), generation starts in it from definite threshold of driving electron beam current. Depending on generation wave range the threshold current strikes from fraction of ampere to dozens of amperes. In order to rich laser saturation, from hundreds to thousands electron bunches are required. Simple estimations give the value from units up to tens joules of bunches train energy in order to rich FEL saturation for infrared wave range (approximately 20 - 25 MeV of bunches energy and 3 A of pick current, bunch length being 1 cm). A beam with parameters mentioned might be obtained in rf superconducting linac operating in stored energy mode. The advantage of such approach is simplified linac power supply since dozens watts cw rf generator is required only to rich necessary accelerating voltage. At the same time the energy spread arising from beam loading may be compensated by additional cavities exited at shifted frequencies. In this paper Maxwell equations are used for beam-cavity interaction analysis. The bunch energy loss or the same the voltage induced by radiating bunch is expressed in terms of cavity external parameters. The detailed analysis of beam energy spread compensation is carried out followed by an example showing the reality of FEL schema suggested.

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TUPSA028

QWR resonator Cavities Electrodynamics Simulations for new Nuclotron-NICA Injector

simulation, linac, impedance, acceleration

273

M. Gusarova, T. Kulevoy, M.V. Lalayan, S.M. Polozov, N.P. Sobenin, D.V. Surkov, S.A. Terekhov, S.E. Toporkov, V. Zvyagintsev
MEPhI, Moscow, Russia
A.V. Butenko, A.O. Sidorin, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia
V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

New linac-injector for Nuclotron-NICA is planned to consist of quarter-wave coaxial cavities (QWR) having velocities of ~0.07c and ~0.12c (beam energy from 5 to 17 MeV). These cavities are to be superconducting and operating at 162 MHz. Current results of the QWR cavities electrodynamics simulations and geometry optimizations are presented.

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TUPSA030

Regulation of the Waveguide Coupling Factor of Standing Wave Linear Accelerator

coupling, resonance, insertion, electron

279

D.S. Yurov
MSU, Moscow, Russia
V.I. Shvedunov
LEA MSU, Moscow, Russia
V.I. Shvedunov
SINP MSU, Moscow, Russia

Regulation of the waveguide coupling factor of standing wave linear accelerator allows to adjust the value of accelerated current, keeping the reflected RF power close to zero. This ensures the most efficient use of RF energy and absence of overvoltage in the waveguide elements. The paper presents studies results for various methods of coupling factors regulation with continuous wave (CW) normal conducting linear accelerator used as an example. The results of calculations and measurements on the mock-up of the accelerating structure are presented.

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TUPSA031

The Cascade Interference Switch Comprising a Transmission Resonator

plasma, simulation, distributed, high-voltage

282

S.A. Gorev, S.N. Artemenko, V.S. Igumnov
TPU, Tomsk, Russia

The new concept of microwave interference switches is reported. Interference switch is based on series of H-plane T-junctions (cascade switch) in the view of decreasing switched power at Off state and comprises irises in both its own input and output arms. At On state the irises act as a transmission resonator localizing the nodes of the standing wave at the junctions. Such distribution is expected to decrease the plasma losses. It was shown with a simulation that the cascade switch with additional irises increases the efficiency of the active microwave compressors. The simulation was made with CST studio and COMSOL.

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TUPSA035

Estimation of Multipacting in CDS Structure

multipactoring, simulation, electron, coupling

288

I.V. Rybakov
RAS/INR, Moscow, Russia
I.I. Isaev
DESY Zeuthen, Zeuthen, Germany

The Cut Disk Structure (CDS) is recommended for replacement of the first cavity of the main part of INR linac. For the cavity work stability there should be no multipactor at operating regime. CDS structure was first set on exploitation at DESY PITZ electron linac. For this cavity according to the analytical estimation multipaction should appear at the operating power level in coupling cells, but it was not approved by the numerical simulation with both accelerating and coupling modes excitation for RF energy transfer along the cavity. The multipactor appears only with the secondaty emission yield (SEY) growth which could happen if the inner surface of the cavity is polluted. The results of multipactor investigation in CDS PITZ were used as reference for the CDS structure for the first cavity of the main part of INR linac. The analytical estimation and numerical simulation of multipactor in CDS INR structure shows the appearance of the discharge in coupling cells with the OFC copper SEY for the operating regime of the cavity. An option for the multipactor damping with the forced excitation of oscillations in coupling cell with voltage higher than upper multipactor limit was considered.

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TUPSA036

Manufacturing Tolerances Estimation for Proton Linac Cavities

coupling, linac, proton, simulation

291

I.V. Rybakov, V.V. Paramonov, A.K. Skasyrskaya
RAS/INR, Moscow, Russia

The definition of manufacturing tolerances is one of the stages of accelerating structure construction. In case of proton linacs the value of accelerating field homogeneity is a critical parameter. It depends both on cells frequencies perturbations and the coupling coefficient perturbations. These values could be obtained using the numerical simulations of the characteristic electromagnetic oscillations in the cell. There is the method that allows the reduction of the simulations time and to avoid separate simulations for each geometrical parameter of the structure. This method was improved and extended for the pi/2-wave, pi-wave and travelling wave structures. Several examples of the method application, including the structure for the first cavity of the main part of INR linac, are presented.

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TUPSA040

S-Band Choke Mode Cavity for Low Energy Storage Ring

HOM, storage-ring, electron, scattering

300

L. Ovchinnikova, V.I. Shvedunov
SINP MSU, Moscow, Russia
A. Ryabov
IHEP, Moscow Region, Russia
V.I. Shvedunov
LEA MSU, Moscow, Russia

Several variants of a low-energy storage ring for Thomson scattering X-ray source were considered in *. The most promising variant "C" of the ring with small dimensions and large dynamic aperture has also large momentum compaction factor, which would lead to too long bunches with RF cavity operating at 714 MHz, so shorter wavelength must be used. In this paper we present results of optimization of S-band double-cells cavity with parasitic mode damping by chokes similar to **. Interaction of the bunch circulating in the ring with cavity parasitic modes is simulated.
* L. Ovchinnikova, V. Shvedunov, A. Mikhailichenko et al.. A comparative study of low energy compact storage rings for a thomson scattering x-ray source. Proc. of IPAC-16, 2016, pp. 3308-3310.
** T. Shintake, The Choke Mode Cavity, Jpn. J. Appl. Phys, Vol. 31,1992, pp. L1567-L1570, No. 1lA

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TUPSA046

Experimental Analysis of Dipole Modes in Elliptical Cavity

simulation, experiment, impedance, dipole

313

Ya.V. Shashkov, M.V. Lalayan, N.P. Sobenin
MEPhI, Moscow, Russia
A. Orlov
NRNU, Moscow, Russia

The experimental measurements of transverse shunt impedance for higher order modes TM110 and TE111 for S-band elliptical cavity were carried out. The experiments using dielectric and metallic spheres as perturbing objects and with ring probe were done.

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TUPSA050

Electron Beam Stability in the Energy Recovery Linac for the Lithographic Free Electron Laser

electron, linac, undulator, radiation

319

Ya.V. Getmanov, O.A. Shevchenko, N.A. Vinokurov
BINP SB RAS, Novosibirsk, Russia
N.A. Vinokurov
NSU, Novosibirsk, Russia

According to microelectronic production leaders the lithography based on the free electron laser (FEL) could become the main technology for the elements mass production with scale to 5 nm in the nearest future. One of the main problem is the absence of the working FEL with required parameters. The feasibility study of those FEL based on superconducting energy-recovery linac (ERL) was made in Budker INP. The ERL average current is limited by longitudinal and transverse instabilities, caused by interaction between electron beam and its induced fields in the superconducting cavities. The estimations of the threshold currents and ERL parameters were made.

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TUPSA068

Simulation of S-Band RF Gun with RF Beam Control

cathode, gun, controls, electron

345

A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
M.V. Maltseva
NSU, Novosibirsk, Russia

The design and operation of electron RF gun with RF beam control are described. Results of numerical simulation of electromagnetic fields and beam dynamics are presented. RF gun consists of two resonators operating at E010 mode with 180 degrees phase shift at frequency of 2856 MHz. RF control is carried out via coaxial resonator with grid-cathode capacity. Accordint to result of the simulation, RF gun with RF control allows producing electron bunches with duration of 50 ps, energy of about 3 MeV and the energy spread of about 5%.

Poster TUPSA068 [0.996 MB]

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TUPSA069

Optimization of an RF Probe Vicinity for RF Gun Cavities

gun, HOM, simulation, quadrupole

348

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

To provide electron bunches with exceptionally high brightness, RF gun cavity should operate with the extreme electric and magnetic fields. The RF probe is required for the mostly reliable and precise measurements of the RF field phase and amplitude directly from the cavity. The implementation of an RF probe in the cavity design generates a set of coupled problems, which is analyzed and compared for different operating frequencies and different RF pulse length. Both general dependencies and particularities are considered. Some recommendations for practical choice of the RF probe are presented.

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WEPSB013

On Approach for Resonant Frequency Tuning in Drift Tube Structures on the Designing Stage

simulation, controls, target, electron

386

I. Skudnova, V.V. Altsybeyev
Saint Petersburg State University, Saint Petersburg, Russia

Current research considers the interdigital H-mode linear resonant accelerator with drift tubes mounted inside the cavity. The focus of the study has been on the dependence of resonant frequency on the parameters of the geometry. Since Alternating-Phase-Focusing (APF) type of accelerator is investigated, the efficiency of the operation depends on the synchronization of the charged particle velocity and accelerating field oscillations. Researchers can control it by the variation of longitudinal size of the cells of the structure (periods). On the other hand, the effective performance of the resonant system requires the equality of resonant frequencies of its cells, because it affects the uniformity of accelerating field distribution along the axis. The diversity of cells longitudinal sizes causes the deviation from the particular value of the resonant frequency. This aberration can be eliminated by the adjustment of other geometry parameters: period's length, gap ratio and drift tube diameter. We have conducted the study to analyze the relation between resonant frequency and these values. Using the this dependency we can tune the geometry parameters of each period in the structure. We first create the computer-aided design (CAD) geometry model of the accelerator cavity. Then, using Comsol Multiphysics, the platform for physics-based modeling and simulation, we conduct the calculation of resonant frequencies.

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WEPSB032

Numerical Analysis of Cavity Mode Operation and Electron Beam Dynamics in Lebedev Institute Microtron

microtron, electron, operation, simulation

428

V.S. Dyubkov, Y.A. Bashmakov, Y. Lozeev
MEPhI, Moscow, Russia
Y.A. Bashmakov
LPI, Moscow, Russia

Dynamics of electrons in classic microtron is studied. 3D cavity model is developed and electromagnetic field distribution is simulated. Dependence of output beam parameters on microtron operation mode is investigated and discussed.

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WEPSB073

Design Study of the Proton Linac for Radiopharmaceuticals Production

DTL, linac, rfq, focusing

524

G. Kropachev, A.I. Balabin, T. Kulevoy, D.N. Selesnev, A. Sitnikov
ITEP, Moscow, Russia
T. Kulevoy
MEPhI, Moscow, Russia

The 8 MeV 200 MHz linac for acceleration of quasi cw 0.2 mA proton beam is under development at ITEP. The linac is designed for radiopharmaceuticals production which will be used in the Positron-Emission Tomography. The linac includes RFQ and DTL sections with 6D-beam matching between them. The DTL section has modular structure and consists of separated individually phased IH-cavities with beam focusing by permanent magnet quadrupoles located between the cavities. This DTL structure provides linac compactness and enables its tuning and commissioning cavity by cavity. Results of beam dynamic simulation and electrodynamics characteristics of linac cavities are presented.

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THPSC055

Electrodynamic Characteristics of RF-Deflector for Bunch Shape Monitor

simulation, electron, impedance, insertion

659

D.A. Chermoshentsev, A. Feschenko, S.A. Gavrilov
RAS/INR, Moscow, Russia
D.A. Chermoshentsev
MIPT, Dolgoprudniy, Moscow Region, Russia
D.A. Chermoshentsev
Skoltech, Moscow, Russia

Bunch shape monitors, based on a transverse RF-scanning of secondary electrons, are used for measurements of particles longitudinal distribution in bunches at different linear ion accelerators. The phase resolution of such monitors depends crucially on accuracy of fabrication and tuning of RF-deflector, thus preliminary simulations of its electrodynamic characteristics are of importance for subsequent commissioning of the monitor. Simulations of some basic operational electrodynamic parameters and results of experimental measurements are presented.

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THPSC060

The Longitudinal Distribution and Bunch Length Measurements at VEPP-2000 Collider

collider, impedance, electron, detector

673

Yu. A. Rogovsky, E. Perevedentsev, V. Volkov, Yu.M. Zharinov
BINP SB RAS, Novosibirsk, Russia

The paper describes the bunch length measurement system for VEPP-2000 collider, equiped with optical analysers based on LI-602 dissector, which provides permanent measurements of the longitudinal beam profile. Potential well distorsion lengthening was measured at different bunch currents for the energies below 500 MeV. First measurements reveals the presence of microwave instabilty with turbulent emittance growth. The thresholds of these processes was used to estimate the values of reactive part of the longitudinal impedance. Measured energy loss factors was compared with computer simulations for the RF cavity. All results will be discussed and further estimations will be given.

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THPSC067

Coaxial Quarter Wavelength Impedance Converter for Coupling Control of Triode Cavity

impedance, coupling, electron, gun

689

K. Torgasin, T. Kii, K. Masuda, K. Morita, K. Nagasaki, H. Ohgaki, S. Suphakul, H. Zen
Kyoto University, Kyoto, Japan

A quarter wavelength coaxial cavity has been developed for triode-type thermionic RF gun. The triode-type RF gun is a modification of present 4.5 cell thermionic RF gun of KU-FEL (Kyoto University Free Electron Laser) facility with aim to mitigate the back'bombardment effect. Thereby a coaxial quarter wavelength cavity with cathode material shall be added to the main 4.5 cell accelerating body. The coaxial cavity has the function of pre-buncher to control the injection phase and power of electron bunches into the main accelerating body*. Transient tests have demonstrated the quarter wavelength cavity to be undercoupled. However, for operation at high beam loading conditions overcoupled conditions are required. In order to control the coupling we have developed an external air side coaxial quarter wavelength impedance converter. The design of the impedance converter enables operation at high RF power (<20 kV) without changing the cavity geometry. In this work we present our design and performance of quarter wavelength impedance converter as applied to quarter wavelength triode cavity.
* K. Torgasin et al., Cold Test of the Coaxial Cavity for Thermionic Triode Type RF Gun, in Proc. IPAC, 2013, pp.324-326.

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THPSC073

Development of the Hardware-Software Complex PIRS-5 for Field Measurements in Accelerating Structures

software, hardware, controls, impedance

702

G.S. Pomogaybo, M.V. Lalayan, S.E. Toporkov
MEPhI, Moscow, Russia

Hardware-software complex "PIRS-5" was developed to make measurements in warm accelerating structures. The idea was to create full-automatic measuring system, which can measure electrical field at the bead position with non-resonant and resonant pull techniques. PIRS-5 has postprocessor, which calculate electrical component from the frequency, reflection or transmission coefficient, shunt and effective shunt impedance. This work describes the construction of this complex, its mathematical part and possible future modifications.

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