Title :
TiN coating of the PEP-II low-energy aluminum arc vacuum chambers
Author :
Kennedy, K. ; Harteneck, B. ; Millos, G. ; Benapfl, M. ; King, F. ; Kirby, R.
Author_Institution :
Lawrence Livermore Nat. Lab., CA, USA
Abstract :
The PEP-II Low-Energy Ring will operate at a nominal energy of 3.1 GeV with a positron beam current of 2.1 A. Design parameters for vacuum components are 3.5 GeV at 3 A. The arc vacuum system is based on an aluminum antechamber concept. It consists of 192 pairs of 2 m long magnet chambers and 5.5 m long pumping chambers. Titanium nitride coating of the entire positron duct is needed in order to suppress beam instabilities caused by multipactoring and the “electron-cloud” effect. An extensive R&D program has been conducted to develop coating parameters that give proper stoichiometry and a suitable thickness of TiN. The total secondary emission yield of TiN-coated aluminum coupons has been measured after the samples were exposed to air and again after electron-beam bombardment. A coating facility has been built to cope with the large quantity of production chambers and the very tight schedule requirements
Keywords :
accelerator magnets; aluminium; ceramics; colliding beam accelerators; electromagnets; electron accelerators; particle beam stability; protective coatings; secondary electron emission; storage rings; titanium compounds; vacuum apparatus; vacuum pumps; 2 m; 2.1 A; 3 A; 3.1 GeV; 3.5 GeV; 5.5 m; Al; PEP-II Low-Energy Ring; PEP-II low-energy Al arc vacuum chambers; TiN; TiN coating; antechamber concept; beam instabilities suppression; electron-beam bombardment; electron-cloud; magnet chambers; multipactoring; positron beam current; positron duct; pumping chambers; total secondary emission yield; vacuum components; Aluminum; Coatings; Ducts; Elementary particle vacuum; Positrons; Production; Tin; Titanium; Vacuum arcs; Vacuum systems;
Conference_Titel :
Particle Accelerator Conference, 1997. Proceedings of the 1997
Conference_Location :
Vancouver, BC
Print_ISBN :
0-7803-4376-X
DOI :
10.1109/PAC.1997.753276
