Discharge cleaning

The Diels-Alder liquid-phase reaction between 1,4-benzoquinone (A, C6H4O2) and cy-clopentadiene (B, C5H6) to form the adduct CnHm02 is second-order with a rate constant kx = 9.92 X 10 6 m3 mol 1 s 1 at 25°C (Wassermann, 1936). Calculate the size (m3) of a batch reactor required to produce adduct at the rate of 125 mol h 1, if cAo = cBo = 100 mol m 3, the reactants are 90% converted at the end of each batch (cycle), the reactor operates isothermally at 25°C, and the reactor down-time (for discharging, cleaning, charging)... 

The reaction mixture will be discharged when the conversion of the acetic acid is 30 per cent. A time of 30 min is required between batches for discharging, cleaning, and recharging. Determine the volume of the reactor required. 

A conditioning method which is very effective for reducing particle desorption coefficients without resorting to high temperature bake-out is discharge cleaning (1, 31, 37) The... 

While residual gas measurements are useful for optimizing discharge cleaning processes, concomitant surface analysis measurements have been necessary to elucidate the mechanisms involved in the surface chemistry. A number of in-sltu surface studies (26-30. 32-35) have been performed on tokamaks where... 

Figure 5. Observed change in the elemental surface composition of hydrocarbon-covered 304 stainless steel and Inconel as a function of exposure to hydrogen discharge cleaning. The stainless steel sample was exposed to glow discharge cleaning in the PDXTokamak (Ref. 37J and the Inconel sample was exposed to pulse discharge cleaning in the TFR Tokamak. Key , C SS substrate A, O SS substrate ...

Figure 6. X-ray photoelectron spectra of type 304 stainless steel. Key (a,d) initial surface (b,e) after exposure to H2 glow discharge cleaning and (c,f) after A+ ion bombardment. (Reproduced, with permission, from Ref. 35. Copyright 1980, American Institute of Physics.

Figure 7 Secondary ion mass spectra of type 304 before (a) and after (b) exposure to Hs discharge cleaning. (Reproduced, with permission from Ref. 44. Copyright 1980, NHPC.)...

The studies reviewed In this paper have produced data on the surface chemistry and vacuum behavior of a variety of technological materials, Including the effects of hydrogen discharge cleaning on structural metals such as stainless steel... 

The initial contamination of a Tokamak plasma used to be dominated by oxygen and carbon which are released from the wall and from the limiter due to desorption (see Sect. 5.5.). These impurities were of primary concern in most machines until the discharge cleaning technique came to be routinely used54). In addition to the various desorption processes, a number of other impurity release mechanisms need to be considered. Among these are ... 

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