TY - CONF AU - Huque, N.A. AU - Castilla, A. AU - Daly, E.F. AU - De Silva, S.U. AU - Drachuk, E. AU - Henry, J. AU - Marchlik, M. AU - Xiao, B.P. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Development of a Prototype 197 MHz Crab Cavity for the Electron-Ion Collider at JLab J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Thomas Jefferson National Accelerator Facility (JLab) is currently developing a prototype 197 MHz Radio-Frequency Dipole (RFD) crab cavity as part of the Electron-Ion Collider (EIC) to be built at Brookhaven National Laboratory (BNL). Cryomodules containing these cavities will be part of Hadron Storage Ring (HSR) of the EIC. The prototype cavity is constructed primarily of formed niobium sheets of thickness 4.17 mm, with machined niobium parts used as interfaces where tight tolerancing is required. The cavity¿s large size and complex features present a number of challenges in fabrication, tuning, and RF testing. Structural and forming analyses have been carried out to optimize the design and fabricated processes. An overview of the design phase and the current state of fabrication are presented in this paper. PB - JACoW Publishing CP - Geneva, Switzerland SP - 685 EP - 690 KW - cavity KW - GUI KW - niobium KW - HOM KW - electron DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB051 UR - https://jacow.org/srf2023/papers/wepwb051.pdf ER - TY - CONF AU - Raut, N.K. AU - Ciovati, G. AU - De Silva, S.U. AU - Delayen, J.R. AU - Dhakal, P. AU - Khanal, B.D. AU - Tiskumara, J.K. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Temperature, RF Field, and Frequency Dependence Performance Evaluation of Superconducting Niobium Half-Wave Coaxial Cavity J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Recent advancement in superconducting radio frequency cavity processing techniques, with diffusion of impurities within the RF penetration depth, resulted in high quality factor with increase in quality factor with increasing accelerating gradient. The increase in quality factor is the result of a decrease in the surface resistance as a result of nonmagnetic impurities doping and change in electronic density of states. The fundamental understanding of the dependence of surface resistance on frequency and surface preparation is still an active area of research. Here, we present the result of RF measurements of the TEM modes in a coaxial half-wave niobium cavity resonating at frequencies between 0.3 - 1.3 GHz. The temperature dependence of the surface resistance was measured between 4.2 K and 1.6 K. The field dependence of the surface resistance was measured at 2.0 K. The baseline measurements were made after standard surface preparation by buffered chemical polishing. PB - JACoW Publishing CP - Geneva, Switzerland SP - 691 EP - 695 KW - cavity KW - niobium KW - SRF KW - radio-frequency KW - experiment DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB052 UR - https://jacow.org/srf2023/papers/wepwb052.pdf ER - TY - CONF AU - Raut, N.K. AU - Dhakal, P. AU - Ganey, T.D. AU - Powers, T. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Simulation of the Dynamics of Gas Mixtures during Plasma Processing in the C75 Cavity J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Plasma processing using a mixture of noble gas and oxygen is a technique that is currently being used to reduce field emission and multipacting in accelerating cavities. Plasma is created inside the cavity when the gas mixture is exposed to an electromagnetic field that is generated by applying RF power through the fundamental power or higher-order mode couplers. Oxygen ions and atomic oxygen are created in the plasma which breaks down the hydrocarbons on the surface of the cavity and the residuals from this process are removed as part of the process gas flow. Removal of hydrocarbons from the surface increases the work function and reduces the secondary emission coefficient. This work describes the initial results of plasma simulation, which provides insight into the ignition process, distribution of different species, and interactions of free oxygen and oxygen ions with the cavity surfaces. The simulations have been done with an Ar/¿2 plasma using COMSOL® multiphysics. These simulations help in understanding the dynamics and control of plasma inside the cavity and the exploration of different gas mixtures. PB - JACoW Publishing CP - Geneva, Switzerland SP - 696 EP - 700 KW - cavity KW - plasma KW - electron KW - simulation KW - SRF DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB053 UR - https://jacow.org/srf2023/papers/wepwb053.pdf ER - TY - CONF AU - Powers, T. AU - Brock, N.C. AU - Ganey, T.D. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - In Situ Plasma Processing of Superconducting Cavities at JLab, 2023 Update J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Jefferson Lab has an ongoing R&D program in plasma processing which just completed a round of production processing in the CEBAF accelerator. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the secondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The initial focus of the effort was processing C100 cavities by injecting RF power into the HOM coupler ports. Results from processing cryomodules in the CEBAF accelerator as well as vertical test results will be presented. The goal will be to improve the operational gradients and the energy margin of the linacs. This work will describe the systems and methods used at JLAB for processing cavities using an argon-oxygen gas mixture as well as a helium-oxygen gas mixture. Before and after plasma processing results will also be presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 701 EP - 705 KW - cavity KW - plasma KW - cryomodule KW - HOM KW - radiation DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB054 UR - https://jacow.org/srf2023/papers/wepwb054.pdf ER - TY - CONF AU - Ruber, R.J.M.Y. AU - Eslinger, A.B. AU - Geng, R.L. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - First Experience with Liquid Nitrogen Cleaning J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Field emission caused by microscopic particulate contamination is a limiting factor for the performance of superconducting RF (SRF) cavities. In an SRF accelerator, particulates may be transported over the surface of an operational SRF cavity, becoming field emitters and consequentially degrading the performance of the SRF cavity. The most commonly used method for removing particulates from cavity surfaces is high-pressure ultra-pure water rinsing. We are developing a novel high-pressure liquid nitrogen cleaning technique that may possibly enable superior cleaning power and particulate removal from cavities in a cryomodule without taking apart the cryomodule components. This technique provides cleaning mechanisms beyond what are accessible by its high-pressure water counterpart and leaves no residues on the cleaned surface. We present the test setup and first experience. PB - JACoW Publishing CP - Geneva, Switzerland SP - 706 EP - 708 KW - cavity KW - SRF KW - cryomodule KW - operation KW - booster DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB055 UR - https://jacow.org/srf2023/papers/wepwb055.pdf ER - TY - CONF AU - Zhao, L. AU - Cheng, G. AU - Ciovati, G. AU - Wilson, K.M. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Copper Plating Qualification Process for the Fundamental Power Coupler Waveguides for CEBAF Cryomodules J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - To provide sufficient energy for CEBAF operation, cryomodules and components are being refurbished yearly as necessary. Copper plated fundamental power coupler waveguides are important components of the cryomodules. The integrity and quality of copper plating is critical to reduce the heat load from the waveguides into the He bath at 2.07 K. A search of copper plating resources is underway for plating or re-plating CEBAF-style waveguides. This effort ensures a continuous capability of copper plating on cryomodule components, especially on waveguides. To qualify plating vendors, the waveguide copper plating specifications were revisited, and a thorough plating evaluation process is being developed. The evaluation process ranges from coupon testing to sample waveguide qualification. Recent results are summarized and future work is planned. PB - JACoW Publishing CP - Geneva, Switzerland SP - 790 EP - 793 KW - GUI KW - cryomodule KW - SRF KW - cavity KW - operation DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB087 UR - https://jacow.org/srf2023/papers/wepwb087.pdf ER - TY - CONF AU - Xu, W. AU - Conway, Z.A. AU - Daly, E.F. AU - Guo, J. AU - Rimmer, R.A. AU - Smith, K.S. AU - Zaltsman, A. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Theoretical Model of External Q Tuning for an SRF Cavity with Waveguide Tuner J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - A wide range of electron beam energies (5 ¿ 18 GeV) and beam currents (0.2 ¿ 2.5 A) in EIC Electron Storage Ring (ESR) operating scenarios requires a capability of adjusting coupling factor up to a factor of 20 for the 591 MHz Superconducting Radio Frequency (SRF) cavities, which contains two fundamental power couplers (FPC) delivering continuous wave (CW) 800 kW RF power to the beam. Currently, adjusting external Q of a SRF cavity is done by varying protrusion of FPC¿s inner conductor in beam pipe or using three stub tuner to adjust external Q value, which either has limit on tuning range or limit on operating power. This paper presents a method of tuning the FPC external Q by a multiple-waveguide tuner, which allows for high power, wide tuning range operations. The theoretical model of matching beam impedance with waveguide tuner and detailed matching conditions and limits will be presented. Follow the theoretical model, a preliminary design of a 3D waveguide tuner will be presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 794 EP - 796 KW - cavity KW - GUI KW - SRF KW - operation KW - electron DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB089 UR - https://jacow.org/srf2023/papers/wepwb089.pdf ER - TY - CONF AU - Barbagallo, C. AU - Barriere, B.S. AU - Clement, C.S. AU - Duchesne, P. AU - Gerard, R.L.A. AU - Gerigk, F. AU - Henry, J. AU - Kaabi, W. AU - Maurin, P.M. AU - Olivier, G. AU - Olry, G. AU - Overstreet, S.A. AU - Park, G.-T. AU - Rimmer, R.A. AU - Roset, S. AU - Wang, H. AU - Zomer, Z.F. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Simulations and First RF Measurements of Coaxial HOM Coupler Prototypes for PERLE SRF Cavities J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Superconducting Radio-Frequency (SRF) linac cryomodules are foreseen for the high-current multi-turn energy recovery linac PERLE (Powerful Energy Recovery Linac for Experiments). Coaxial higher order mode (HOM) couplers are the primary design choice to absorb beam-induced power and avoid beam instabilities. We have used 3D-printed and copper-coated HOM couplers for the prototyping and bench RF measurements on the copper PERLE cavities. We have started a collaboration with JLab and CERN on this effort. This paper presents electromagnetic simulations of the cavity HOM-damping performance on those couplers. Bench RF measurements of the HOMs on an 801.58 MHz 2-cell copper cavity performed at JLab are detailed. The results are compared to eigenmode simulations in CST to confirm the design. RF-thermal simulations are conducted to investigate if the studied HOM couplers undergo quenching. PB - JACoW Publishing CP - Geneva, Switzerland SP - 831 EP - 834 KW - HOM KW - cavity KW - damping KW - coupling KW - simulation DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB103 UR - https://jacow.org/srf2023/papers/wepwb103.pdf ER - TY - CONF AU - Owen, P.D. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Prevention of Dual-Mode Excitation in 9-Cell Cavities for LCLSII-HE J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Dual-Mode Excitation, also referred to as mode-mixing, is a superposition of two pi modes in an SRF cavity. In 9-cell TESLA cavities used for the LCLSII-HE project, the two modes that are commonly excited are the pi mode (1300.2 MHz), and the 7/9 pi mode (1297.8 MHz). During vertical cavity qualification testing, it is regularly observed that emitted power at the frequency of the 7/9 pi mode grows, despite the RF system only driving the pi mode. When this happens, the RF power measurement system is unable to differentiate between the superimposed modes which invalidates any data taken. A new RF control solution prevents the 7/9 pi mode from being excited. A second RF control system is connected to drive the 7/9 pi mode. The loop phase for driving this mode is determined, then shifted by 180 degrees, thus providing a negative feedback to the undesired mode. Because this off-resonance power can be very small, it does not interfere with the high-power measurements of the fundamental pi mode. At Jefferson Lab, we are now able to test a cavity for the LCLSII-HE project with no complications from mode-mixing, which allows for CW processing of high-gradient multipacting. PB - JACoW Publishing CP - Geneva, Switzerland SP - 852 EP - 854 KW - cavity KW - resonance KW - controls KW - feedback KW - SRF DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB110 UR - https://jacow.org/srf2023/papers/wepwb110.pdf ER - TY - CONF AU - Maniscalco, J.T. AU - Aderhold, S. AU - Arkan, T.T. AU - Bafia, D. AU - Bevins, M.E. AU - Checchin, M. AU - Gonnella, D. AU - Grabowski, A.J. AU - Hogan, J. AU - Kaluzny, J.A. AU - Porter, R.D. AU - Posen, S. AU - Reece, C.E. AU - Savransky, D. AU - Vennekate, H. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Flux Expulsion Testing for LCLS-II-HE Cavity Production J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Nitrogen-doped niobium SRF cavities are sensitive to trapped magnetic flux, which decreases the cavity intrinsic Q₀. Prior experimental results have shown that heat treatments to 900°C and higher can result in stronger flux expulsion during cooldown; the precise temperature required tends to vary by vendor lot/ingot of the niobium material used in the cavity cells. For LCLS-II-HE, to ensure sufficient flux expulsion in all cavities, we built and tested single-cell cavities to determine this required temperature for each vendor lot of niobium material to be used in cavity cells. In this report, we present the results of the single-cell flux expulsion testing and the Q₀ of the nine-cell cavities built using the characterized vendor lots. We discuss mixing material from different vendor lots, examine the lessons learned, and finally present an outlook on possible refinements to the single-cell technique. PB - JACoW Publishing CP - Geneva, Switzerland SP - 876 EP - 879 KW - cavity KW - cryomodule KW - niobium KW - SRF KW - ECR DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB120 UR - https://jacow.org/srf2023/papers/wepwb120.pdf ER - TY - CONF AU - Dhakal, P. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Thermodynamic Properties of Srf Niobium J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Bulk and thin films of niobium are the materials of choice in fabricating superconducting radio frequency (SRF) cavities for modern particle accelerators and quantum computing applications. The thermodynamic properties of Nb are of particular interest in heat management in cryogenic environments. Here, we report the results of measurements of the thermodynamic properties of niobium used in the fabrication of superconducting radio frequency (SRF) cavities. The temperature and magnetic field dependence of thermal conductivity, Seebeck coefficient, and specific heat capacity was measured on bulk niobium samples. PB - JACoW Publishing CP - Geneva, Switzerland SP - 884 EP - 887 KW - cavity KW - SRF KW - niobium KW - radio-frequency KW - cryogenics DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB125 UR - https://jacow.org/srf2023/papers/wepwb125.pdf ER - TY - CONF AU - Pudasaini, U. AU - Cheban, S. AU - Eremeev, G.V. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - First Results from Nanoindentation of Vapor Diffused Nb₃Sn Films on Nb J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - The mechanical vulnerability of the Nb₃Sn-coated cavities is identified as one of the significant technical hurdles toward deploying them in practical accelerator applications in the not-so-distant future. It is crucial to characterize the material’s mechanical properties in ways to address such vulnerability. Nanoindentation is a widely used technique for measuring the mechanical properties of thin films that involves indenting the film with a small diamond tip and measuring the force-displacement response to calculate the film’s elastic modulus, hardness, and other mechanical properties. The nanoindentation analysis was performed on multiple vapor-diffused Nb₃Sn samples coated at Jefferson Lab and Fermilab coating facilities for the first time. This contribution will discuss the first results obtained from the nanoindentation of Nb₃Sn-coated Nb samples prepared via the Sn vapor diffusion technique. PB - JACoW Publishing CP - Geneva, Switzerland SP - 888 EP - 892 KW - cavity KW - SRF KW - linac KW - experiment KW - accelerating-gradient DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB126 UR - https://jacow.org/srf2023/papers/wepwb126.pdf ER - TY - CONF AU - Wang, H. AU - Anderson, J.P. AU - Jordan, K. AU - Moeller, C.P. AU - Rimmer, R.A. AU - Thackston, K.A. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Schaa, Volker R.W. ED - Thomas, Paul W. TI - Demonstration of Magnetron as an Alternative RF Source for SRF Accelerators J2 - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023 CY - Grand Rapids, MI, USA T2 - International Conference on RF Superconductivity T3 - 21 LA - english AB - Magnetron has been considered as alternate high-efficiency, low-cost RF sources for linacs and storage rings [1] for national labs and industrial applications. After the demonstration of magnetrons power to drive and combine for a radio frequency cavity at 2450 MHz in CW mode, we have used trim coils adding to a water-cooled magnetron and amplitude modulation feedback to further suppress the side-band noise to -46.7 dBc level. We also demonstrated the phase-locking to an industrial grade cooking magnetron transmitter at 915 MHz with a 75 kW CW power delivered to a water load by using a -26.6 dBc injection signal [2]. The sideband noise from the 3-Phase SCRs DC power supply can be reduced to -16.2 dBc level. Further noise reduction and their power combining scheme using magic-tee and cavity type combiners for higher power application (2x75kW) are to be presented. We intent to use one power station to drive the normal conducting and superconducting RF cavities for the inductrial linac. We also going to demonstarte a vertical SRF cavity test with a high input coupling Q using a 2.45GHz magnetron and comparing with a baseline test result using a solid state amplifier. PB - JACoW Publishing CP - Geneva, Switzerland SP - 902 EP - 906 KW - injection KW - controls KW - cavity KW - power-supply KW - klystron DA - 2023/09 PY - 2023 SN - 2673-5504 SN - 978-3-95450-234-9 DO - doi:10.18429/JACoW-SRF2023-WEPWB131 UR - https://jacow.org/srf2023/papers/wepwb131.pdf ER -