Risks of explosion mixing O2 and H2 in Ar magnetron plasma?

[atomica68]

I am interested in adding simultaneously O2 and H2 in a magnetron sputtering discharge ignited in Ar at a pressure of 3*10-2 mbar. The discharge is driven by a RF generator (13.56 MHz, 60 - 120W). The target is W. Can anyone told me if I can expect at any explsion to apear due to simultanoously presence of O2 and H2 in the discharge?
Thank you in advance for responses.

 

[Quantum Defect]

I think you can figure this out yourself. How much energy would be released if all of the H2 and O2 in your experiment reacted? How does this compare with the amount of energy going into the experiment from the RF generator?

 

[Borek]

Exactly my thought - simple calculation of reaction enthalpy given number of moles of the substance should tell you if there is any risk involved. Especially taking into account you work in vacuum, so the chamber must be quite sturdy.

 

[KMikk]

What is the potential applied across the tungsten and the plasma? Also, what is the flow rate of the two gasses? I work with ICPMS and have experience dealing with argon plasma ionization, but ours is at 1500W (~10,000 K) and potentials of 5 - 10V. The hydrogen and oxygen should ionize instantly going into the plasma. They will want to recombine afterwards as one would expect, but if the potential is high enough, you may accelerate the ions fast enough to hit the target before then. The concept is the same with ICPMS where the ions are accelerated and focused with lenses to prevent recombination. Typically, when tuning a plasma to produce less recombination, a lower flow rate is used. Explosion is not typically seen unless too much gas is being pumped in.