Scientific Foundations of Vacuum Technique

Effect of geometry and surface condensation on the behavior of a torsion effusion cell

“…Dushman ( 4 ) gives a s e t of p r a c t i c a l limits which demarcate t h e boundaries of the t h r e e flow regimes a s follows:…”

“…I t i s herein assumed . Substituting t h i s f o r GT i n equation (3)(4)(5)(6)(7)(8)(9) gives, a f t e r simpliNow, represent m by the mean molecular mass, i ; .…”

“…' where 0 and' 8 a r e angles between t h e l i n e segment and t h e 11 normals t o t h e surfaces when t h e two p o i n t s can see" each other, and i s zero i f they a r e obstructed. Equation (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), with i t s variants, w i l l be employed i n t h e ensuing discussion,…”

“…where kc = (1 + 3 / 8 l / a ) -l , and 1 and a a r e the length and radius, respectively, of the o r i f i c e , I n comparing t h i s t o equation (2)(3)(4)(5), one observes t h a t kc i s a f a c t o r which corrects f o r the f i n i t e o r i f i c e depth. Clausing (13), however; demons t r a t e s t h a t Dushmanls formulation of kc i s v a l i d only i n the l i m i t as t h e channel depth, i .…”

“…. by equation (2)(3)(4) coupled t o an o r i f i c e ' a s described by e q u a t i o n (2-5), Dushman ( 1 2 ) obtains ' t h e f o llowing conductance f o r a r e a l c y l i n d r i c a l . o r i f i c e :…”