TY - CONF AU - Nagaitsev, S. AU - Broemmelsiek, D.R. AU - Huang, Z. AU - Jarvis, J.D. AU - Kim, Y.K. AU - Lumpkin, A.H. AU - Ruan, J. AU - Saewert, G.W. AU - Stupakov, G. AU - Thurman-Keup, R.M. ED - Biedron, Sandra ED - Simakov, Evgenya ED - Milton, Stephen ED - Anisimov, Petr M. ED - Schaa, Volker R.W. TI - Noise in Intense Electron Bunches J2 - Proc. of NAPAC2022, Albuquerque, NM, USA, 07-12 August 2022 CY - Albuquerque, NM, USA T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - We report on our investigations into density fluctuations in electron bunches. Noise and density fluctuations in relativistic electron bunches, accelerated in a linac, are of critical importance to various Coherent Electron Cooling (CEC) concepts as well as to free-electron lasers (FELs). For CEC, the beam noise results in additional diffusion that counteracts cooling. In SASE FELs, a microwave instability starts from the initial noise in the beam and eventually leads to the beam microbunching yielding coherent radiation, and the initial noise in the FEL bandwidth plays a useful role. In seeded FELs, in contrast, such noise interferes with the seed signal, so that reducing noise at the initial seed wavelength would lower the seed laser power requirement. Status of the project will be presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 128 EP - 131 KW - electron KW - laser KW - radiation KW - FEL KW - experiment DA - 2022/10 PY - 2022 SN - 2673-7000 SN - 978-3-95450-232-5 DO - doi:10.18429/JACoW-NAPAC2022-MOPA34 UR - https://jacow.org/napac2022/papers/mopa34.pdf ER - TY - CONF AU - Hu, H. AU - Bafia, D. AU - Kim, Y.K. ED - Biedron, Sandra ED - Simakov, Evgenya ED - Milton, Stephen ED - Anisimov, Petr M. ED - Schaa, Volker R.W. TI - Examining the Effects of Oxygen Doping on SRF Cavity Performance J2 - Proc. of NAPAC2022, Albuquerque, NM, USA, 07-12 August 2022 CY - Albuquerque, NM, USA T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - Superconducting radiofrequency (SRF) cavities are resonators with extremely low surface resistance that enable accelerating cavities to have extremely high quality factors (Q₀). High (Q₀) decreases the capital required to keep accelerators cold by reducing power loss. The performance of SRF cavities is largely governed by the surface composition of the first 100 nm of the cavity surface. Impurities such as oxygen and nitrogen have been observed to yield high Q₀, but their precise roles are still being studied. Here, we compare the performance of cavities doped with nitrogen and oxygen in terms of fundamental material properties to understand how these impurities affect performance. This enables us to have further insight into the underlying mechanisms that enable these surface treatments to yield high Q₀ performance. PB - JACoW Publishing CP - Geneva, Switzerland SP - 196 EP - 198 KW - cavity KW - SRF KW - niobium KW - ECR KW - radio-frequency DA - 2022/10 PY - 2022 SN - 2673-7000 SN - 978-3-95450-232-5 DO - doi:10.18429/JACoW-NAPAC2022-MOPA67 UR - https://jacow.org/napac2022/papers/mopa67.pdf ER - TY - CONF AU - Bossard, M.K. AU - Banerjee, N. AU - Brandt, J.A. AU - Cathey, B.L. AU - Kim, Y.K. AU - Krieg, M.A. AU - Nagaitsev, S. AU - Stancari, G. ED - Biedron, Sandra ED - Simakov, Evgenya ED - Milton, Stephen ED - Anisimov, Petr M. ED - Schaa, Volker R.W. TI - Thermionic Sources for Electron Cooling at IOTA J2 - Proc. of NAPAC2022, Albuquerque, NM, USA, 07-12 August 2022 CY - Albuquerque, NM, USA T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - We are planning a new electron cooling experiment at the Integrable Optics Test Accelerator (IOTA) at Fermilab for cooling ~2.5 MeV protons in the presence of intense space-charge. Here we present the simulations and design of a thermionic electron source for cooling at IOTA. We particularly discuss parameters of the thermionic source electrodes, as well as the simulation results. We also present a new electron source test-stand at the University of Chicago, which will be used to test the new thermionic electron source, as well as other electron sources. In addition, we discuss results from analyzing the test stand operations with a currently existing electron source. Furthermore, we present future steps for the test stand as well as production and commissioning of the thermionic source at IOTA. PB - JACoW Publishing CP - Geneva, Switzerland SP - 588 EP - 591 KW - electron KW - vacuum KW - cathode KW - proton KW - space-charge DA - 2022/10 PY - 2022 SN - 2673-7000 SN - 978-3-95450-232-5 DO - doi:10.18429/JACoW-NAPAC2022-WEYE6 UR - https://jacow.org/napac2022/papers/weye6.pdf ER - TY - CONF AU - Tiwari, G. AU - Kim, K.-J. AU - Lindberg, R.R. ED - Biedron, Sandra ED - Simakov, Evgenya ED - Milton, Stephen ED - Anisimov, Petr M. ED - Schaa, Volker R.W. TI - Arrival Time and Energy Jitter Effects on the Performance of X-Ray Free Electron Laser Oscillator J2 - Proc. of NAPAC2022, Albuquerque, NM, USA, 07-12 August 2022 CY - Albuquerque, NM, USA T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - We report on the effects of electron beam arrival time and energy jitter on the power level and the fluctuations of the output of an X-ray FEL oscillator (XFELO). For this study, we apply the FEL driven paraxial resonator model of XFELO along with an analytical reflectivity profile to mimic the phase shift and spectral filtering effects of Bragg-crystals. The thresholds for acceptable timing jitters and energy jitters are determined in terms of the fluctuations of the steady-state power output. We explore potential ways to mitigate the power output fluctuations in the presence of unavoidable electron beam jitters. PB - JACoW Publishing CP - Geneva, Switzerland SP - 866 EP - 869 KW - FEL KW - cavity KW - electron KW - laser KW - radiation DA - 2022/10 PY - 2022 SN - 2673-7000 SN - 978-3-95450-232-5 DO - doi:10.18429/JACoW-NAPAC2022-THYD6 UR - https://jacow.org/napac2022/papers/thyd6.pdf ER - TY - CONF AU - Howard, K. AU - Bafia, D. AU - Grassellino, A. AU - Kim, Y.K. ED - Biedron, Sandra ED - Simakov, Evgenya ED - Milton, Stephen ED - Anisimov, Petr M. ED - Schaa, Volker R.W. TI - Analysis of Low RRR SRF Cavities J2 - Proc. of NAPAC2022, Albuquerque, NM, USA, 07-12 August 2022 CY - Albuquerque, NM, USA T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - Recent findings in the superconducting radio-frequency (SRF) community have shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. Success has been found in nitrogen-doping, diffusion of the native oxide into the niobium surface, and thin films of alternate superconductors atop a niobium bulk cavity. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurity profile of niobium with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of recent impurity-based improvements can be better understood and improved upon. Additionally, we performed surface treatments, low temperature baking and nitrogen-doping, on low RRR cavities to evaluate how the intentional addition of more impurities to the RF layer affects performance. We have found that low RRR cavities experience low temperature-dependent BCS resistance behavior more prominently than their high RRR counterparts. The results of this study have the potential to unlock a new understanding on SRF materials. PB - JACoW Publishing CP - Geneva, Switzerland SP - 877 EP - 880 KW - cavity KW - SRF KW - niobium KW - accelerating-gradient KW - radio-frequency DA - 2022/10 PY - 2022 SN - 2673-7000 SN - 978-3-95450-232-5 DO - doi:10.18429/JACoW-NAPAC2022-THYE5 UR - https://jacow.org/napac2022/papers/thye5.pdf ER -