Design of the button beam position monitor for PEP-II

Author

Kurita, N. ; Martin, D. ; Smith, S. ; Ng, C. ; Nordby, M. ; Perkins, C.

Author_Institution

Linear Accel. Center, Stanford Univ., CA, USA

Volume

4

fYear

1995

fDate

1-5 May 1995

Firstpage

2512

Abstract

The beam position monitor (BPM) was designed to provide a robust UHV feedthru and a reliable electromagnetic sensor. Stringent resolution requirements at low beam currents, bunch parameters, along with mechanical and chamber requirements produced challenges in the electrical, thermal, and structural design of the BPM´s. Numerical modeling and experimental analyses were used to optimize the design. The higher order modes (HOM´s) and beam impedance were modeled using MAFIA. Measurements agreed with the calculated 1 Ω transfer impedance at the 952 MHz signal processing frequency, and the first two HOM´s found in MAFIA. Tests and analysis both showed the button signal power approaching 40 W. Temperature and stress distributions were analyzed using this power loading with ANSYS. An electronic grade CuNi was selected for the BPM to reliably weld into the copper chambers. Pin seal and compressive joints were considered for the insulator vacuum seals. Both glassy ceramic-to-metal and ceramic-to-metal seals were evaluated

Keywords

beam handling techniques; electron accelerators; glass-metal seals; high energy physics instrumentation computing; numerical analysis; particle beam diagnostics; particle beam stability; position measurement; seals (stoppers); storage rings; welding; 1 ohm; 40 W; 952 MHz; ANSYS code; CuNi; MAFIA code; PEP-II electron storage ring; beam impedance; bunch parameters; button beam position monitor design; chamber requirements; compressive joint; electromagnetic sensor; glassy ceramic-to-metal seals; higher order modes; insulator vacuum seals; low beam currents; numerical modeling; pin seal joint; power loading; resolution requirements; robust UHV feedthru; stress distribution; temperature distribution; transfer impedance; welding; Beams; Design optimization; Frequency measurement; Impedance measurement; Mechanical sensors; Monitoring; Numerical models; Robustness; Seals; Signal analysis;

fLanguage

English

Publisher

ieee

Conference_Titel

Particle Accelerator Conference, 1995., Proceedings of the 1995

Conference_Location

Dallas, TX

Print_ISBN

0-7803-2934-1

Type

conf

DOI

10.1109/PAC.1995.505601

Filename

505601