19 research outputs found
Millikelvin measurements of permittivity and loss tangent of lithium niobate
Lithium Niobate is an electro-optic material with many applications in
microwave signal processing, communication, quantum sensing, and quantum
computing. In this letter, we present findings on evaluating the complex
electromagnetic permittivity of lithium niobate at millikelvin temperatures.
Measurements are carried out using a resonant-type method with a
superconducting radio-frequency (SRF) cavity operating at 7 GHz and designed to
characterize anisotropic dielectrics. The relative permittivity tensor and loss
tangent are measured at 50 mK with unprecedented accuracy.Comment: 5 pages, 4 figure
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The progress in developing superconducting third harmonic cavity
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
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Production and test results of SC 3.9-GHz accelerating cavity at Fermilab
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
RF thermal and new cold part design studies on TTF-III input coupler for Project-X
RF power coupler is one of the key components in superconducting (SC) linac.
It provides RF power to the SC cavity and interconnects different temperature
layers (1.8K, 4.2K, 70K and 300K). TTF-III coupler is one of the most promising
candidates for the High Energy (HE) linac of Project X, but it cannot meet the
average power requirements because of the relatively high temperature rise on
the warm inner conductor, some design modifications will be required. In this
paper, we describe our simulation studies on the copper coating thickness on
the warm inner conductor with RRR value of 10 and 100. Our purpose is to
rebalance the dynamic and static loads, and finally lower the temperature rise
along the warm inner conductor. In addition, to get stronger coupling, better
power handling and less multipacting probability, one new cold part design was
proposed using 60mm coaxial line; the corresponding multipacting simulation
studies have also been investigated.Comment: 5 pages, 12 figures. Submitted to Chinese Physics C (Formerly High
Energy Physics and Nuclear Physics
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Final Results on RF and Wake Kicks Caused by the Couplers for the ILC Cavity
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
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Single Spoke Cavities for Low-energy Part of CW Linac of Project X.
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)
COMPARISON OF BUFFERED CHEMICAL POLISHED AND ELECTROPOLISHED 3.9 GHZ CAVITIES*
Abstract 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
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Comparison of buffered chemical polished and electropolished 3.9 GHz cavities
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
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CW Room Temperature Re-Buncher for the Project X Front End
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