Lifetime of titanium filament at constant current

Conference · Thu Jan 01 00:00:00 EST 1981

OSTI ID:6568479

Chou, T S; Lanni, C

Titanium Sublimation Pump (TSP) represents the most efficient and the least expensive method to produce Ultra High Vacuum (UHV) in storage rings. In ISABELLE, a proton storage accelerator under construction at Brookhaven National Laboratory, for example, TSP provides a pumping speed for hydrogen of > 2 x 10/sup 6/ l/s. Due to the finite life of titanium filaments, new filaments have to be switched in before the end of filament burn out, to ensure smooth operation of the accelerator. Therefore, several operational modes that can be used to activate the TSP were studied. The constant current mode is a convenient way of maintaining constant evaporating rate by increasing the power input while the filament diameter decreases as titanium evaporates. The filaments used in this experiment were standard Varian 916-0024 filaments made of Ti 85%, Mo 15% alloy. During their lifetime at a constant current of 48 amperes, the evaporation rate rose to a maximum at about 10% of their life and then flattened out to a constant value, 0.25 g/hr. The maximum evaporation rate occurs coincidently with the recrystallization of 74% Ti 26% Mo/sup 2/ from microstructure crystalline at higher titanium concentration to macrostructure crystalline at lower titanium concentration. As the macrocrystal grows, the slip plane develops at the grain boundary resulting in high resistance at the slip plane which will eventually cause the filament burn out due to local heating.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6568479
• Report Number(s): BNL-29051; CONF-810314-23; TRN: 81-006791
• Resource Relation: Conference: Particle accelerator conference, Washington, DC, USA, 11 Mar 1981
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
42 ENGINEERING
ISABELLE STORAGE RINGS
VACUUM PUMPS
GETTERS
SERVICE LIFE
EXPERIMENTAL DATA
FILAMENTS
TITANIUM
DATA
ELEMENTS
EQUIPMENT
INFORMATION
LABORATORY EQUIPMENT
METALS
NUMERICAL DATA
PUMPS
STORAGE RINGS
TRANSITION ELEMENTS
430303* - Particle Accelerators- Experimental Facilities & Equipment
420700 - Engineering- Vacuum Engineering- (-1987)