PAC07 - List of Authors (Solyak, N.)

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Solyak, N.

Paper	Title	Page
WEOBAB02	Studies of Emittance Bumps and Adaptive Alignment method for ILC Main Linac	1973
	N. Solyak, V. Ivanov, C. S. Mishra, K. Ranjan Fermilab, Batavia, Illinois
	Funding: U. S. Department of Energy International Linear Collider (ILC) is a proposed electron-positron accelerator requiring very small spot-size at the interaction point, and thus necessitates very tight tolerances on beamline elements. For static tuning of the machine a few methods like dispersion-free steering (DFS) or kick minimization (KM) techniques was proposed. The further suppression of emittance growth can be achieved by using close orbit emittance bumps. Stability of ILC is determined by the stability of the site, additional noises of beamline component, energy and kicker jitter and performance of the train-to-train and intra-train feedback. We discuss the performances of the Adaptive Alignment technique, which keeps accelerator dynamically aligned in presence of ground motion an technical noises. This presentation is an overview of two posters THPMN107 and THPMN108, presented at PAC07.
	Slides
WEPMN066	Progress Towards Development of a Superconducting Traveling Wave Accelerating Structure	2182
	P. V. Avrakhov LPI, Moscow A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio S. Kazakov KEK, Ibaraki N. Solyak Fermilab, Batavia, Illinois V. P. Yakovlev Omega-P, Inc., New Haven, Connecticut
	In the ILC project the required accelerating gradient is higher than 35 MeV/m. For current technology the maximum acceleration gradient in SC structures is limited mainly by the value of the surface RF magnetic field. In order to increase the gradient, the RF magnetic field is distributed homogeneously over the cavity surface (low-loss structure), and coupling to the beam is improved by introducing aperture ?noses? (re-entrant structure). These features allow gradients in excess of 50 MeV/m to be obtained for a singe-cell cavity. Further improvement of the coupling to the beam may be achieved by using a TW SC structure with small phase advance per cell. Calculations show that an additional gradient increase by up to 40% is possible if a p/2 TW SC structure is employed. However, a TW SC structure requires a SC feedback waveguide to return the few GW of circulating RF power from the structure output back to the structure input. We describe a single-cell test TW SC structure with a feedback waveguide. The test cavity is designed to demonstrate the possibility of achieving a significantly higher gradient than existing SC structures.
WEPMN093	Multipactor Simulations in Superconducting Cavities	2248
	I. G. Gonin, N. Solyak Fermilab, Batavia, Illinois J. F. DeFord, B. Held STAR, Inc., Mequon
	The multipactor (MP) is a well-known phenomenon. The existence of resonant trajectories can lead to electron avalanche under certain field level and surface conditions. In this paper we describe features of the extension of Analyst software - PT3P code developed for MP simulations in a real 3D RF structures, such as cavities, couplers, RF windows etc. Also we present the results of MP simulations in HOM couplers of TESLA, SNS β=0.61 and β=0.81 and FNAL 3-rd harmonic cavities. We discuss the comparison of simulations with experimental results.
WEPMN098	New HOM Coupler Design for 3.9 GHz Superconducting Cavities at FNAL	2259
	T. N. Khabiboulline, I. G. Gonin, N. Solyak Fermilab, Batavia, Illinois
	Last few years Fermilab is developing the superconducting third harmonic section for the FLASH (TTF/DESY) upgrade. The results of vertical tests of 9-cell Nb cavities didn't reached the designed accelerating gradient. The main gradient limitation is multipacting in HOM coupler. In this paper we present the results of vertical tests accompanied with 3D Analyst simulations of multipacting. Also we discuss the RF design of a new HOM couplers. The goal of a new design is to eliminate multipacting and to increase the frequency of second resonance of the HOM. Increasing the frequency will decrease the electric and magnetic fields having the goal to decrease the thermal load on antenna.
WEPMN100	RF Design and Processing of a Power Coupler for Third Harmonic Superconducting Cavities	2265
	J. Li, E. R. Harms, T. Kubicki, D. J. Nicklaus, D. R. Olis, P. S. Prieto, J. Reid, N. Solyak Fermilab, Batavia, Illinois T. Wong Illinois Institute of Technology, Chicago, Illinois
	Funding: U. S. Department of Energy The FLASH user facility providing free electron laser radiation is built based on the TTF project at DESY. Fermilab has the responsibility for the design and processing of a third harmonic, 3.9 GHz, superconducting cavity which is powered via a coaxial power coupler. Six power couplers have been manufactured at CPI after successful design of the power coupler including RF simulation, multipacting calculation, and thermal analysis. The power couplers are being tested and processed with high pulsed power in an elaborate test stand at Fermilab now. This paper presents the RF design and processing work of the power coupler.
WEPMN101	Coupling Interaction Between the Power Coupler and the Third Harmonic Superconducting Cavity	2268
	J. Li, N. Solyak Fermilab, Batavia, Illinois T. Wong Illinois Institute of Technology, Chicago, Illinois
	Funding: U. S. Department of Energy Fermilab has developed a third harmonic superconducting cavity operating at the frequency of 3.9 GHz to improve the beam performance for the FLASH user facility at DESY. It is interesting to investigate the coupling interaction between the SRF cavity and the power coupler with or without beam loading. The coupling of the power coupler to the cavity needs to be determined to minimize the power consumption and guarantee the best performance for a given beam current. In this paper, we build and analyze an equivalent circuit model containing a series of lumped elements to represent the resonant system. An analytic solution of the required power from the generator as a function of the system parameters has also been given based on a vector diagram.
WEPMN111	3.9 GHz Superconducting Accelerating 9-cell Cavity Vertical Test Results	2295
	T. N. Khabiboulline, C. A. Cooper, N. Dhanaraj, H. Edwards, M. Foley, E. R. Harms, D. V. Mitchell, A. M. Rowe, N. Solyak Fermilab, Batavia, Illinois W.-D. Moller DESY, Hamburg
	The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve beam performances of the FLASH (TTF/DESY) facility. In the frame of collaboration Fermilab will provide DESY with a cryomodule containing a string of four cavities. In addition, a second cryomodule with one cavity will be fabricated for installation in the Fermilab photo-injector, which will be upgraded for the ILC accelerator test facility. The first results of vertical tests of 9-cell Nb cavities didn?t reached the designed accelerating gradient. The main problem is multipactoring in HOM couplers, which leads to quenching and overheating of the HOM couplers. New HOM couplers with improved design integarated to next 9-cell cavities. In this paper we present all results of vertical tests.
WEPMS057	Innovative Modular, Multiple Power Levels, 325 MHz Spokes Cavities Power Couplers	2475
	Q. S. Shu, G. F. Chen, F. H. Lu, I. M. Phipps, J. T. Susta AMAC, Newport News, Virginia T. N. Khabiboulline, N. Solyak Fermilab, Batavia, Illinois
	Funding: Footnotes: The project was funded by the US Department of Energy under contract DE-FG02-05ER84346 In order to increase the protons energy up to 8 GeV in a driver Linac, the particles must be accelerated through various stages and three different power levels (25kW, 100kW and 210kW) are required for the 325 MHz Fermilab Proton Driver couplers. The problem identified by the project is that no High RF power coupler for these cavities has ever been produced using US industrial capabilities. AMAC proposed a novel resolution by development of innovative modular, multiple power levels, 325 MHz spoke cavities power couplers, which to meet three type cavities with one coupler design. The simulation and concept design are presented. The results of HFSS, MAFIA, ANSYS, and Multipacting are also discussed.
WEPMS087	Conceptual Design of an L-Band Recirculating Superconducting Traveling Wave Accelerating Structure	2538
	A. Kanareykin, P. V. Avrakhov, Z. Liu Euclid TechLabs, LLC, Solon, Ohio W. Gai ANL, Argonne, Illinois S. Kazakov KEK, Ibaraki N. Solyak Fermilab, Batavia, Illinois V. P. Yakovlev Omega-P, Inc., New Haven, Connecticut
	Funding: This research is supported by the US Department of Energy We describe a conceptual design for a superconducting traveling wave accelerator for the ILC. The RF feedback system plus phase shifter can redirect the accelerating wave that passed through the STWA section back to the input of the accelerating structure. In this paper, the STWA cell shape optimization, coupler cell design and rat race ring coupler in the feedback loop are presented. The STWA cell shape is similar to the LL cavity with a 60 mm disk diameter. A 9-cell STWA operates at the mode with group velocity as low as 0.0106 c. Both the ratio of peak electric field and magnetic field to the axial electric field are smaller than in the TESLA 9-cell cavity. The STWA structure has more cells per unit length than a TESLA structure but provides an accelerating gradient higher than a TESLA structure, consequently reducing the cost. The designed rat race directional coupler with four ports has ?3 dB direct coupling coefficients, 16.5 MHz bandwidth between ?30 dB isolations and 1.1 MHz bandwidth between ?30 dB reflection coefficients. Effects of the mechanical tolerances are also discussed.
THPMN107	Study of Emittance Bumps in The ILC Main Linac	2960
	N. Solyak, K. Ranjan Fermilab, Batavia, Illinois
	Funding: U. S. Department of Energy This paper reports the studies of using global emittance tuning bumps to limit the emittance growth to very small values in the main linac of the proposed International Linear Collider (ILC) machine. Simulation studies indicate that closed-orbit emittance bumps, when used after local or quasi-local beam based alignment techniques, can be utilized to further suppress the emittance growth in the ILC main linac. A series of simulations are performed to find the optimal number of bumps and their locations. A more general method of optimizing the emittance bumps in the ILC main linac is also discussed.
THPMN108	Study of Adaptive Alignment as Beam Based Alignment in ILC Main Linac in the Presence of Ground Motion	2963
	N. Solyak, V. Ivanov, C. S. Mishra, K. Ranjan Fermilab, Batavia, Illinois
	Funding: U. S. Department of Energy The proposed International Linear Collider (ILC) machine requires extremely small transverse emittances of the beam to achieve desired luminosity. A very precise alignment of the beamline elements, both in main linac and in beam delivery system, is required to limit the emittance growth. However, ground motion (GM) and technical noise continuously misaligns the elements and hence spoils the effect of alignment. It is thus very important to understand and analyze the effect of GM on the performance of ILC. Also, it is imperative to find an effective dynamic alignment procedure to preserve the transverse emittances in the presence of GM. In this paper we study the effect of GM and technical noise on the proposed ILC main linac. Initial alignment of the Linac is performed through one-to-one and dispersion free steering (DFS). We then study "Adaptive Alignment" method to mitigate the effects of GM and technical noise.
THPMN109	Status of the ILC Main Linac Lattice Design	2966
	A. Valishev, N. Solyak Fermilab, Batavia, Illinois M. Woodley SLAC, Menlo Park, California
	The report describes the present design of the ILC Main Linac lattice. The topics covered include basic element layout, optical functions, and issues centered around the linac following of the Earth's curvature. Also discussed are beam parameter measurements and instrumentation requirements.
WEPMN096	Status of the 3.9-GHz Superconducting RF Cavity Technology at Fermilab	2254
	E. R. Harms, T. T. Arkan, L. Bellantoni, H. Carter, H. Edwards, M. Foley, T. N. Khabiboulline, D. V. Mitchell, D. R. Olis, A. M. Rowe, N. Solyak Fermilab, Batavia, Illinois
	Funding: This work supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U. S. DOE. Fermilab is involved in an effort to assemble 3.9 GHz superconducting RF cavities into a four cavity cryomodule for use at the DESY TTF/FLASH facility as a third harmonic structure. The design gradient of these cavities is 14 MV/m limited by thermal heat transfer. This effort involves design, fabrication, intermediate testing, assembly, and eventual delivery of the cryomodule. We report on all facets of this enterprise from design through future plans. Included will be test results of single 9-cell cavities, lessons learned, and current status.
THPMS072	Superconducting Traveling Wave Ring with High Gradient Accelerating Section	3148
	P. V. Avrakhov Euclid TechLabs, LLC, Solon, Ohio N. Solyak Fermilab, Batavia, Illinois
	Considerable gain of a superconducting linac accelerating gradient provides using of a traveling wave structure instead of a standing wave accelerating section. Preservation of the superconducting structure advantages requires to put the TW accelerating section into a superconducting traveling wave ring (STWR). We discuss two variants of the STWR with one and two feeding couplers. The STWR application allows to increase the superconducting section accelerating gradient up to ~50 MV/m and essentially reduce the price of the section tuning system.