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Coupling interaction between the power coupler and the third harmonic superconducting cavity

Description: 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.
Date: June 1, 2007
Creator: Li, Jianjian; Solyak, Nikolay & Wong, Thomas
Partner: UNT Libraries Government Documents Department

Study of adaptive alignment as beam based alignment in ILC Main Linac in the presence of ground motion

Description: In this work we present simulation results on the effect of ground motion on the main linac performance of the proposed International Linear Collider (ILC), and then use adaptive alignment (AA) technique to correct it. The adaptive alignment technique is investigated for the ILC main linac and its limitations are studied. Then ground motion studies are performed using the simulation program LIAR and the beneficial effects of implementing AA algorithm are further discussed.
Date: June 1, 2007
Creator: Ranjan, Kirti; Solyak, Nikolay; Ivanov, Valenin; Mishra, Shekhar & /Fermilab
Partner: UNT Libraries Government Documents Department

Final Results on RF and Wake Kicks Caused by the Couplers for the ILC Cavity

Description: In the paper the results are presented for calculation of the transverse wake and RF kick from the power and HOM couplers of the ILC acceleration structure. The RF kick was calculated stand-alone by HFSS, CST MWS and COMSOL codes while the wake kick was calculated by GdfidL. The calculation precision and convergence for both cases are discussed and compared to the results obtained independently by other group.
Date: May 1, 2010
Creator: Lunin, Andrei; /Fermilab; Gonin, Ivan; /Fermilab; Solyak, Nikolay; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

Three-cell traveling wave superconducting test structure

Description: Use of a superconducting traveling wave accelerating (STWA) structure with a small phase advance per cell rather than a standing wave structure may provide a significant increase of the accelerating gradient in the ILC linac. For the same surface electric and magnetic fields the STWA achieves an accelerating gradient 1.2 larger than TESLA-like standing wave cavities. The STWA allows also longer acceleration cavities, reducing the number of gaps between them. However, the STWA structure requires a SC feedback waveguide to return the few hundreds of MW of circulating RF power from the structure output to the structure input. A test single-cell cavity with feedback was designed, manufactured and successfully tested demonstrating the possibility of a proper processing to achieve a high accelerating gradient. These results open way to take the next step of the TW SC cavity development: to build and test a travelingwave three-cell cavity with a feedback waveguide. The latest results of the single-cell cavity tests are discussed as well as the design of the test 3-cell TW cavity.
Date: March 1, 2011
Creator: Avrakhov, Pavel; Kanareykin, Alexei; Kazakov, Sergey; Solyak, Nikolay; Wu, Genfa & Yakovlev, Vyacheslav P.
Partner: UNT Libraries Government Documents Department

Single Spoke Cavities for Low-energy Part of CW Linac of Project X.

Description: In the low-energy part of the Project X H-linac three families of 325 MHz SC single spoke cavities will be used, having {beta} = 0.11, 0.21 and 0.4. Single spoke cavity was selected for the linac because of higher r/Q. Results of optimization of all cavities are presented. Results of the beam dynamics optimization for initial stage of the linac with beta=0.11 single spoke cavity are presented at poster MOPEC082 (this conference).
Date: May 1, 2010
Creator: Gonin, Ivan; Champion, Mark; Khabiboulline, Timergali; Lunin, Andrei; Perunov, Nikolay; Solyak, Nikolay et al.
Partner: UNT Libraries Government Documents Department

CW Room Temperature Re-Buncher for the Project X Front End

Description: At Fermilab there is a plan to construct the Project X Injector Experiment (PXIE) facility - a prototype of the front end of the Project X, a multi-MW proton source based on superconducting linac. The construction and successful operations of this facility will validate the concept for the Project X front end, thereby minimizing the primary technical risk element within the Project. The room temperature front end of the linac contains an ion source, an RFQ accelerator and a Medium Energy Beam Transport (MEBT) section comprising a high bandwidth bunch selective chopper. The MEBT length is about 10 m, so three re-bunching CW cavities are used to support the beam longitudinal dynamics. The paper reports a RF design of the re-bunchers along with preliminary beam dynamic and thermal analysis of the cavities.
Date: May 9, 2012
Creator: Romanov, Gennady; Awida, Mohamed H.; Chen, Meiyu; Gonin, Ivan V.; Kazakov, Sergey; Kostin, Roman et al.
Partner: UNT Libraries Government Documents Department

3.9 GHz superconducting accelerating 9-cell cavity vertical test results

Description: The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve the beam performance of the FLASH (TTF/DESY) facility [1]. In the frame of a collaborative agreement, 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 9-cell Nb cavities were tested in a vertical setup and they didn't reach the designed accelerating gradient [2]. The main problem was a multipactor in the HOM couplers, which lead to overheating and quenching of the HOM couplers. New HOM couplers with improved design are integrated in the next 9-cell cavities. In this paper we present all results of the vertical tests.
Date: June 1, 2007
Creator: Khabiboulline, Timergali; Cooper, Charles; Dhanaraj, Nandhini; Edwards, Helen; Foley, Mike; Harms, Elvin et al.
Partner: UNT Libraries Government Documents Department

Production and test results of SC 3.9-GHz accelerating cavity at Fermilab

Description: The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve beam performances for TTF-FEL 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. In this paper we discuss the status of the cavity and coupler production and the first result of cavity tests. It is hoped that this project will be completed during the first half of 2007 and the cryomodule delivered to DESY in this time span.
Date: August 1, 2006
Creator: Khabiboulline, Timergali; Cooper, Charlie; Edwards, Helen; Foley, Mike; Gonin, Ivan; Mitchell, Donald et al.
Partner: UNT Libraries Government Documents Department

The progress in developing superconducting third harmonic cavity

Description: The XFEL and TTF facilities are planning to use section with a few third harmonic cavities (3.9GHz) upstream of the bunch compressor to improve beam performance [1-2]. Fermilab is developing superconducting third harmonic section for the TTFII upgrade. This section will include four cavities equipped with couplers and blade tuners installed in cryostat. Up to now, two cavities are complete and one of them is under test. The status of the cavity development and preliminary test results are presented in this paper.
Date: June 1, 2006
Creator: Solyak, Nikolay; Edwards, Helen; Foley, Mike; Gonin, Ivan; Harms, Elvin; Khabiboulline, Timergali et al.
Partner: UNT Libraries Government Documents Department

Comparison of buffered chemical polished and electropolished 3.9 GHz cavities

Description: Five 3.9 GHz 9 cell cavities have been measured for the DESY FLASH module. These cavities were BCP processed and reached gradients of typically about 25 MV/m with Q drop starting at about 20 MV/m. Recently a few one cell cavities have been processed with EP and at least one has tested to a gradient of 30 MV/m with Q drop starting at about 25 MV/m. We will compare the results and give an update to the thermal analysis in relation to global thermal breakdown at 3.9 GHz.
Date: October 1, 2009
Creator: Edwards, Helen; Cooper, Charlie A.; Ge, Mingqi; Gonin, Ivan V.; Harms, Elvin R.; Khabiboulline, Timergali N. et al.
Partner: UNT Libraries Government Documents Department

RF design and processing of a power coupler for third harmonic superconducting cavities

Description: 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.
Date: June 1, 2007
Creator: Li, Jianjian; Harms, Elvin; Kubicki, Tom; Nicklaus, Dennis; Olis, Daniel; Prieto, Peter et al.
Partner: UNT Libraries Government Documents Department