IPAC2013 - List of Authors (Thangaraj, J.C.T.)

Paper	Title	Page
MOPWA064	Microwave Resonator Diagnostics of Electron Cloud Density Profile in High Intensity Proton Beam	825
	Y.-M. Shin, J. Ruan, C.-Y. Tan, J.C.T. Thangaraj, R.M. Zwaska Fermilab, Batavia, USA
	We have developed an novel technique to accurately estimate the density of dilute electron clouds emitted from high intensity proton beams. The strong phase shift enhancement from multiple reflections of standing microwaves in a resonating beam pipe cavity has been demonstrated with numerical modeling using dielectric approximation and e S-parameter measurements. The equivalent dielectric simulation showed a ~ 10 times phase shift enhancement (Pi-mode, 1.516 GHz) with the cavity beam pipe compared to the waveguide model. The position-dependence of the technique is investigated by overlapping the field distributions of harmonic resonances. The simulation with various positions of dielectric insertions confirmed that resonance peaks in phase-shift spectra corresponding to the relative distance between field-nodes and electron cloud position, which allows for one-dimensional mapping. Preliminary experimental studies based on a bench-top setup confirm the results of the simulation showing that thicker reflectors enhance the phase-shift measurement of the electron cloud density.

Paper

Title

Page

Microwave Resonator Diagnostics of Electron Cloud Density Profile in High Intensity Proton Beam

825

Y.-M. Shin, J. Ruan, C.-Y. Tan, J.C.T. Thangaraj, R.M. Zwaska
Fermilab, Batavia, USA

We have developed an novel technique to accurately estimate the density of dilute electron clouds emitted from high intensity proton beams. The strong phase shift enhancement from multiple reflections of standing microwaves in a resonating beam pipe cavity has been demonstrated with numerical modeling using dielectric approximation and e S-parameter measurements. The equivalent dielectric simulation showed a ~ 10 times phase shift enhancement (Pi-mode, 1.516 GHz) with the cavity beam pipe compared to the waveguide model. The position-dependence of the technique is investigated by overlapping the field distributions of harmonic resonances. The simulation with various positions of dielectric insertions confirmed that resonance peaks in phase-shift spectra corresponding to the relative distance between field-nodes and electron cloud position, which allows for one-dimensional mapping. Preliminary experimental studies based on a bench-top setup confirm the results of the simulation showing that thicker reflectors enhance the phase-shift measurement of the electron cloud density.