Feasibility Study of Using an Electron Beam for Profile Measurements in the SNS Accumulator Ring

The electron beam probe method was suggested for measuring profiles in high power beams. In this method, deflection of a low energy electron beam by the collective field of the high intensity beam is measured. The charge density in the high intensity beam can be restored under certain conditions or estimated by various mathematical techniques. We studied the feasibility of using the electron beam probe for the SNS accumulator ring using computer simulations of the diagnostic setup. Realistic proton beam distributions were used in the simulations. Several profile calculation techniques were explored and the results are reported in this paper.

INTRODUCTION

The design goal for the SNS ring is to accumulate 1.4.10¹⁴ protons per 1ms pulse at a 60Hz repetition rate. Achieving the design beam intensity with acceptable losses is a challenging task, which could be tackled more easily if reliable measurements of the beam profile in the ring are available. Very high beam power density precludes using wires or other interceptive devices for beam profile measurements at peak of stored current when information on the beam size is most important. Non-interceptive diagnostics using an electron beam probe has been successfully tested at several accelerators [1], [2] but with a beam parameters which are very different from that of the SNS ring (see Table 1). The goal of the present work was to investigate the feasibility of using this technique for the SNS ring, study the range of required electron beam parameters, find the fundamental limitations and choose an appropriate profile reconstruction algorithm. Table 1: SNS proton ring beam parameters.

Proton kinetic energy,	1 GeV
Circumference, C	248 m
Longitudinal distribution length	160 m
Number of protons, N	1.4. 1014
Vacuum chamber radius, R	0.1 m
Beam rms radius,	0.01–0.02 1–0.02 m