Electron clearing and dimensional tolerance for the ISA chamber
In the straight sections of the ISA ring, the clearing of the low energy electrons produced by the beam-gas collisions will take place by longitudinal motion. Thus, an electron of low energy, which is prevented from escaping transversely by the attractive field of the beam, will receive successive kicks by the circulating protons and thereby acquire sufficient energy to travel longitudinally toward the clearing electrodes. However, a discontinuity or step in the chamber diameter, which occurs within an axial distance equal to a few diameters, gives rise to a potential difference along the chamber axis. In the case of a section of chambers which has a larger diameter, that is, a small cavity, the two steps result in a longitudinal potential well, or attractive region. It is then necessary that the electrons be given additional energy in order to overcome this longitudinal trapping potential. The ISA design envisions the placement of clearing electrodes at the location of significant chamber discontinuities, particularly in the experimental insertions. An estimate of the magnitude of the diameter discontinuity that can be tolerated without a clearing electrode is given.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- EY-76-C-02-0016
- OSTI ID:
- 7224443
- Report Number(s):
- BNL-22230; TRN: 77-009268
- Country of Publication:
- United States
- Language:
- English
Similar Records
Calculation of the transverse kicks generated by the bends of a hollow electron lens
Electron clearing for the ISA proton beam