Elementary Particles and Fields and String Theory Commons^™

Study Of Microphonic Effects On The C100 Cryomodule For High Energy Electron Beam Accelerators, Caleb James Hull

Mechanical & Aerospace Engineering Theses & Dissertations

The Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson National Laboratory (JLab) is a particle accelerator which can accelerate an electron beam to relativistic speeds and apply the beam onto target samples. The C100 superconducting radio frequency (SRF) cavity is the primary accelerating structure of the C100 cryomodule, one of the many cryomodules which compose the CEBAF linear accelerator. SRF cavities are particularly sensitive to internal and external vibrations that can result in a phenomenon called microphonics which degrade the operational stability of a cryomodule.

The purpose of this thesis is to investigate the significance of mechanical disturbances on …

Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom

Physics Faculty Publications

Superconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 10¹⁰ at 1-2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200-240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb₃Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration …

Modeling Local Crabbing Dynamics In The Jleic Ion Collider Ring, Salvador Sosa Guitron, Vasiliy Morozov, Jean Delayen

Physics Faculty Publications

The Jefferson Lab Electron-Ion Collider (JLEIC) design considers a 50 mrad crossing angle at the Interaction Point. Without appropriate compensation, this could geometrically reduce the luminosity by an order of magnitude. A local crabbing scheme is implemented to avoid the luminosity loss: crab cavities are placed at both sides of the interaction region to restore a head-on collision scenario. In this contribution, we report on the implementation of a local crabbing scheme in the JLEIC ion ring. The effects of this correction scheme on the stability of proton bunches are analyzed using the particle tracking software elegant.

Wakefield Analysis Of Superconducting Rf-Dipole Cavities, Subashini De Silva, Jean Delayen

Physics Faculty Publications

RF-dipole crabbing cavities are being considered for a variety of crabbing applications. Some of the applications are the crabbing cavity systems for LHC High Luminosity Upgrade and the proposed Electron-Ion Collider for Jefferson Lab. The design requirements in the current applications require the cavities to incorporate complex damping schemes to suppress the higher order modes that may be excited by the high intensity proton or electron beams traversing through the cavities. The number of cavities required to achieve the desired high transverse voltage, and the complexity in the cavity geometries also contributes to the wakefields generated by beams. This paper …

Bunch Splitting Simulations For The Jleic Ion Collider Ring, R. Gamage, T. Satogata

Physics Faculty Publications

We describe the bunch splitting strategies for the proposed JLEIC ion collider ring at Jefferson Lab. This complex requires an unprecedented 9:6832 bunch splitting, performed in several stages. We outline the problem and current results, optimized with ESME including general parameterization of 1:2 bunch splitting for JLEIC parameters.

Field Emission Studies Toward Improving The Performance Of Dc High Voltage Photoelectron Guns, Mahzad Bastaninejad

Mechanical & Aerospace Engineering Theses & Dissertations

Field emission is the main mechanism that prevents DC high voltage photoemission electron guns from operating at the very high bias voltages required to produce low emittance beams. Gas conditioning is shown to eliminate field emission from cathode electrodes used inside DC high voltage photoelectron guns. Measurements and simulation results indicate that gas conditioning eliminates field emission from cathode electrodes via two mechanisms: sputtering and implantation, with the benefits of implantation reversed by heating the electrode. The field emission characteristics of 5 stainless steel electrodes varied significantly upon the initial application of voltage but improved to nearly the same level …