Capture Pumping Technology by K. Welch

By K. Welch

This can be a functional textbook written to be used through engineers, scientists and technicians. it isn't meant to be a rigorous medical remedy of the subject matter, as this is able to fill a number of volumes. quite, it introduces the reader to the basics of the subject matter, and offers adequate references for an in-depth research of the topic through the technologist. the writer has a life-time educating credential within the California neighborhood collage process. additionally, he has taught technical classes with the yank Vacuum Society for roughly 35 years. scholars attending a lot of those sessions have backgrounds various from high-school graduates to Ph.D.s in technical disciplines. this is often an incredibly tricky classification profile to coach. This e-book nonetheless endeavors to arrive this similar viewers. easy algebra is needed to grasp lots of the fabric. yet, the calculus is utilized in derivation of a few of the equations. the writer hazards use of the 1st individual I , rather than the writer , and you rather than the reader . either are regarded as in bad style whilst writing for ebook within the clinical group. besides the fact that, I am scripting this ebook for you as the topic is fascinating, and that i get pleasure from instructing you, probably, whatever new. The e-book is written extra within the vein of a one-on-one dialogue with you, instead of the writer lecturing to the reader. There are anecdotes, and examples of a few mess ups and successes i've got had during the last forty-five years in vacuum comparable actions, i'm going to test to not understate both. finally, there are a couple of equations which if memorised may help you as a vacuum technician. There are under a dozen equations and part that many ideas of thumb to memorize, that allows you to be drawn on time an back in designing, working and trouble-shooting any vacuum process.

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A " m o d e l " f o r t h e n e t p a s s a g e of g a s t h r o u g h a n a p e r t u r e c o n d u e t a n c e s e p a r a t i n g m a n i f o l d s at d i f f e r e n t p r e s s u r e s . 1 Conductance Model Applications Species and Temperature Dependence We have used the above conductance model to predict the flow of gas through an aperture in a vacuum system. However, we have not specified the type of ~as. 4) that the Vrms of any gas species is proportional to (T / M) 7" of that species. We know, for example, that for a given T, He molecules move about in a vacuum system much faster than do N2 molecules.

There are often approximations which afford sufficient accuracy to adequately predict the behavior of gases in your system. 10, respectively. 5) is an exact expression for the conductance of a rectangular tube. 4)), with diameter D and length L, with that of a rectangular tube of dimensions a, b and the same L, where: a × b = 7t D 2 . 4), which you memorized, will usually provide more than sufficient accuracy in your calculations. 4), equations applicable to an air conductance, to derive the value of a conductance for other gases.

In a plot similar to Fig. 1, there would be some uncertainty in the placement of S(P) along the P-axis. The response times of the gauge and gauge electronics may cause errors in speed measurements. Also, problems of gauge outgassing will obscure the data if tubular ionization gauges are used to determine vessel pressure during a high vacuum pumpdown measurement. An example of this will be given in the chapter on cryopumping. 2 S i n g l e G a u g e D o m e M e t h o d This method, requiring an apparatus similar to that illustrated in Fig.

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