Mechanical Features of Electron-Ring Compressors

The technology of electron-ring compressors draws more heavily on controlled thermonuclear research than on conventional accelerators. This is dictated by the rapidly rising, intense magnetic fields (> 50 kG in < 1 ms), the required ultrahigh vacuum (≈10-9 torr), and the need for extensive diagnostics and instrumentation during the development phase. Interesting mechanical features of the Berkeley Compressor 3, Compressor 4, and Compressor 5 electron-ring research apparatus are described, including ceramic chamber design, ceramic-metal and ceramic-ceramic joining techniques, cryopumping, vacuum bakeout practices, and novel diagnostic probes suitable for ultrahigh vacuum service.