Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
74 (1993), S. 5327-5340
ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Aging of proportional counters in CF4/iC4H10 mixtures is studied as a function of gas composition. Anode surfaces are analyzed by Auger electron spectroscopy. Anode-wire deposits are formed from 95/5 and 90/10 mixtures of CF4/iC4H10; etching of deposits occurs in 50/50 and 80/20 mixtures of CF4/iC4H10 and in pure CF4. Gold-plated wires are resistant to aging resulting from chemical attack by CF4, but non-gold-plated wires are too reactive for use in CF4-containing gases. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained discharge current is observed in CF4 and CF4-rich gases. Principles of low-pressure rf plasma chemistry are used to interpret the plasma chemistry in avalanches (≥1 atm, dc). To understand anode aging in CF4/iC4H10 gases, a four-part model is developed considering: (i) plasma polymerization of iC4H10; (ii) etching of wire deposits by CF4; (iii) deposition that occurs as a result of radical scavenging in strongly etching environments; and (iv) reactivity of the wire surface. Practical guidelines suggested by the model and application of the model to other fluorine-containing gases are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.354234
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