Abstract
Sputtering by charge exchange (CX) atoms of the diagnostic duct wall was suggested as the mechanism of the appearance of deposits on diagnostic windows of fusion devices, or on the “first mirrors” (FM) in ITER. The rate of deposit growth was estimated as a balance between the deposition rate of wall material, D, and sputtering of the deposit, S. For these estimation the dependencies of the sputtering yield on the projectile energy and incidence angle were used. It was found that the duct length to its diameter ratio, L/ d, is an important parameter. The D value exceeds several times S value if L/ d > 2, but D/ S is less than 1 in the case of a short duct, L/ d ≪ 1, and also in the case of a very long duct, L/ d⩾10. Based on such a mechanism, the duct structure with diaphragms made of refractory metals was proposed to decrease significantly the rate of deposit growth.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
