RuPAC-2010 - List of Keywords (coupling)

A B C D E F G H I K L M O P Q R S T U V W

coupling

Paper	Title	Other Keywords	Page
TUCHC01	Concepts for Rasing RF Breakdown Threshold by Using Multi-Moded Cavities	acceleration, electron, cathode, radiation	24
	S. V. Kuzikov IAP/RAS, Nizhny Novgorod J. L. Hirshfield Yale University, Physics Department, New Haven, CT Y. Jiang Yale University, Beam Physics Laboratory, New Haven, Connecticut S. Kazakov, M. E. Plotkin, A. A. Vikharev Omega-P, Inc., New Haven, Connecticut
	Funding: Work sponsored by in part by US Department of Energy, Office of High Energy Physics (2009). Two multi-mode cavity designs aimed at increasing accelerating gradient are developed. The cavity of the first type has circular cross-section but allows excitation of several equidistantly-spaced eigenmodes by a bunched drive beam. This multi-mode excitation allows to reduce exposure time of the cavity surface by high field, which in this case occupies smaller area. This feature promises to provide more than 30% raise of the threshold in a 3-mode cavity. The second cavity type is axisymmetric but longitudinally asymmetric, and is excited in one mode at the fundamental frequency and the other at the second harmonic. Superposition of these modes always produces a low field on one cavity wall and a high field on the other, with the latter directed so as to prevent electron emission. This feature is also expected to raise the breakdown threshold. Computations show that a structure using such cavities might support an accelerating gradient up to 47% greater than that for a structure using similar single-mode cavities.
	Slides

TUPSA005	A 12 GHz Pulse Compressor and Components for CLIC Test Stand	vacuum, controls, simulation, recirculation	44
	S. V. Kuzikov, A. A. Bogdashov, G. G. Denisov IAP/RAS, Nizhny Novgorod K. M. Schirm, I. Syratchev CERN, Geneva A. A. Vikharev Omega-P, Inc., New Haven, Connecticut
	The X-band power test stand needed for preprocessing and testing of key CLIC RF components is being installed in the test facility CTF3. The test stand includes several 12 GHz XL5 klystrons (50 MW, 1.5 mks) and a pulse compressor of the SLED-I type to obtain over 120 MW peak power at 230 ns pulse length. A compact compressor of this type based on TE01-TE02 beating wave in high Q-factor compressor’s cavities has been designed, produced, and tested at low power level. For testing accelerating structures and so-called "CLIC recirculation principle" of its operation several -3 dB couplers and variable power attenuators were also produced and tested.

TUPSA013	The CDS Parameters for Proton Linac with Moderate Heat Loading	linac, septum, proton, electron	65
	V. V. Paramonov RAS/INR, Moscow
	The Cut Disk Structure (CDS) was originally proposed for high energy linac in L-band or S-band frequency range. CDS combines simultaneously high coupling coefficient, high shunt impedance and small transverse dimensions. For lower particle velocity the structure loses in shunt impedance due to relatively thick partition with internal cooling channels. For moderate heat loading internal cooling is not necessary and partition thickness is limited only by mechanical rigidity. The structure equalizes in shunt impedance with another bi-periodical structures and another CDS advantages come in front. Calculated CDS parameters for proton linac are presented.

WEPSB012	Method to Estimate the Beam and Structure Parameters for the Dispersion Accelerator Parts	emittance, linac, quadrupole, lattice	193
	V. A. Moiseev RAS/INR, Moscow
	The beam dynamics parameters as the transverse emittance information, momentum spread and structure characteristics are determined by treatment of the small number of profile measurements for the dispersion accelerator parts. The reliability of measurements is estimated.

WEPSB024	An Increasing of Electron Beam Lifetime at Injection Energy in SIBERIA-2 Storage Ring by Regulating of Betatron Coupling	injection, betatron, electron, vacuum	218
	A. G. Valentinov, V. Korchuganov, Y. V. Krylov, Y. L. Yupinov RRC, Moscow
	A dedicated synchrotron light source SIBERIA-2 operates at 2.5 GeV with more than 100 mA electron current. An electron beam lifetime at this energy is defined now by vacuum conditions and exceeds 15 hours for 100 mA. The lifetime at injection energy 0.45 GeV is much lower – less than half an hour for typical current value 3–4 mA in singlebunch mode. An analysis of the lifetime value displayed a strong influence of Tushek effect in a presence of a horizontal aperture limitation. A dependence of the lifetime on different parameters (RF voltage, horizontal geometric and dynamic aperture, bunch current, betatron coupling value, electron energy) was analyzed. A betatron coupling regulation was recognized the easiest way to increase lifetime value at injection energy. It was done by two families of skew-quadrupole lenses. A 30–40% increasing of the lifetime was observed for different average values of a bunch current. Also a storing speed was raised because of slower decreasing of a stored current. The beam lifetime during energy ramping was also increased. It led to decreasing of current losses from 5-6% to 1.5–2% during energy rising from 0.45 GeV to 2.5 GeV.

THCHA02	Recovery Process Stability Study in Energy Recovery Accelerator	linac, electron, microtron, free-electron-laser	283
	V. G. Kurakin LPI, Moscow
	Energy recovery technique in rf accelerator based applications allows to save rf power and reduce radioactive background as well. In this operation mode used beam is directed back to the accelerator in decelerating rf phase and returns back its kinetic energy to rf field. Thus, rf generator that feeds linac covers cavities walls rf losses only and those part of beam kinetic energy that is used for useful effects production as well. Vector sum of three fields – induced in the linac by an external rf source, accelerated and decelerated beams – determines energy and phase of the beam at linac exit, and together with beam return path optics amplitude and phase of decelerated bunches and hence third component of mentioned sum. In the case of positive sign of this feedback and sufficient amplification in the closed loop just described instability takes place. The main equations that determine beam-rf cavity interaction in energy recovery rf accelerator are derived, single mode approximation being used. Expressions for small deviation from steady state are obtained followed by stability analysis. Results of calculation for increments of instability presented and discussed.
	Slides

THPSC001	Magnetic Coupled Disk-Loaded Waveguide	impedance, simulation, electron, insertion	319
	N. P. Sobenin, R. O. Bolgov, D. S. Kamenshikov, S. V. Kutsaev, A. Yu. Smirnov, S. E. Toporkov MEPhI, Moscow
	Funding: Research is supported by Russian President grant MK-3835.2009.2 Electrodynamic simulations results of disk loaded waweguide with magnetic field coupled cells are presentred. Different types of accelerating strructures having positive or negative dispersion were considered. Main electrodynamic parameters - shunt impedance, quality factor, group velocity etc. dependances on operation mode and aperture size are presented and discussed. High order modes issues were studied. These structures are proposed for advanced electron linear accelerators designed using conventional or hybrid schemes. Input coupler matching to this structure is studied.

THPSC004	Input Couplers for the Dipole Mode Periodic Structures	simulation, dipole, resonance, emittance	328
	M. V. Lalayan, A. Anisimov, S. V. Kutsaev, A. Yu. Smirnov, N. P. Sobenin MEPhI, Moscow V. V. Paramonov RAS/INR, Moscow A. A. Zavadtsev, D. A. Zavadtsev Nano, Moscow
	Funding: Research is supported by Federal Education agency grant P1141 27.08.2009 and by FCP "Scientific and scientific-educational stuff of innovative Russia" grant. Three variants of the input coupler for the periodic deflecting structure operating at hybrid dipole TM11 mode, with the phase velocity equal to the light velocity are considered: non-symmetric design and two symmetric designs with auxiliary rectangular waveguide and shorting plates in it and with auxiliary cut-off rectangular waveguide. The reflection depending on the coupling window width and on the coupling cell diameter was been investigated for all coupler designs. The reflection coefficient has been calculated in the whole dipole mode passband. The field asymmetry in the beam area has been considered. The eigen frequency of the coupling cell has been calculated.

THPSC014	One Aspect of Thermal Stability for 4-vane RFQ Operation with High Heat Loading	rfq, linac, controls, simulation	352
	V. V. Paramonov RAS/INR, Moscow
	Due to dispersion properties, 4-vane RFQ cavity without resonant coupling is a thermally unstable structure. With deterioration of balance for local detuning, especially near cavity ends, there is a possibility for runaway in the field distribution and related thermal-stress effects. It can, in principle, finish with irreversible plastic deformations and cavity frequency shift. Both the increment and the threshold of instability are proportional to the average dissipated RF power. This possibility increases for long RFQ cavities. Also particularities for the cavity ends design are important. Some general features of this effect are discussed and illustrated with simulations.

FRCHB03	Status of ILU-14 Electron Accelerator	electron, cathode, focusing, feedback	411
	V. S. Podobaev, V. V. Bezuglov, A. A. Bryazgin, K. N. Chernov, V. G. Cheskidov, B. L. Faktorovich, V. A. Gorbunov, I. V. Gornakov, A. V. Ivanov, E. N. Kokin, M. V. Korobeynikov, A. N. Lukin, I. Makarov, N. V. Matyash, S. A. Maximov, G. N. Ostreiko, A. D. Panfilov, V. M. Radchenko, N. D. Romashko, G. V. Serdobintsev, A. V. Sidorov, V. V. Tarnetsky, M. A. Tiunov, V. O. Tkachenko BINP SB RAS, Novosibirsk
	A new high power (up to 100 kW) industrial linear electron accelerator ILU-14 for energy of 7.5–10 MeV is under construction at Budker INP. The accelerator operates at 176 MHz with total efficiency of 26 %, its modular structure allows the electron energy and beam current to be varied within certain limits by changing the modular arrangement. The 5 MeV prototype of the accelerator was created and successfully tested in 2009. The designed average beam current of 600 mA with pulsed power of 2.5 MW and accelerating structure electron efficiency of 68 % were obtained during experiments. Applying an additional RF voltage to the electron gun cathode-grid gap allowed a beam current passing of 96 % with minor beam energy spread. The paper presents results of the numerical and experimental study of the accelerator systems together with the latest tests on the accelerator prototype.
	Slides