ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
A model for the time variation of the Cs coverage on the plasma grid (PG) surface is made and confirmed theoretically. Final coverage is determined by the sum of gaseous and adsorbed Cs on the PG surface. The sum is equal to the Cs not yet adsorbed on the cold surface. The sum decreases on account of the adsorption on the cold surface with time of order of hours. The time of the decrease of the sum is related to the quantity of the seeded Cs. For the case of 600 mg Cs seeding, the sum relaxes to some nonzero value, which gives the optimum coverage on the PG surface. The optimum coverage lasts long. For less than 600 mg Cs seeding the sum relaxes to zero and it makes the coverage go to zero with time of order of hours. The mechanism is shown and an illustrative model calculation is given of the hysteresis in the negative ion current seen when PG temperature is increased and decreased. © 2002 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1431407
