MOTION OF GASEOUS IONS IN STRONG ELECTRIC FIELDS 227 



111 third order, using (87) and (88) and (89) 



These successive approximations lead to the following sequence for 

 the drift velocity {w cos ^) 



(w cos r^f^ = 1.04605 (91a) 



{w cos i^Y'^ = 1.14256 (91b) 



(w cos t}f^ = 1.14616 (91c) 



(w cos t}f^ = 1.14661 (91d) 



We conclude from this sequence that 



{w cos ^) = 1.1467 (92) 



In addition to the drift velocity there is some interest in the energy 

 and the energy partition. For the energy the following numbers are 

 obtained 



{wY^ = 2.1884 (93a) 



{wY^ = 2.3395 (93b) 



{wY^ = 2.3511 (93c) 



(wY' = 2.3531 (93d) 



giving 



(w^) = 2.353 (94) 



A zero order value for {uf^ cos^ ??) cannot be said to exist because the 

 first truncated relation is the condition that a distribution function 

 Jhiw) exists at all. Thus, we can get only three numbers in a sequence 

 approximating {w cos t>) 



{'i/cos^i^f^ = 1.8005 . (95a) 



{w' cos' ^f^ = 1.7696 (95b) 



{w' cos' ^f = 1.7685 (95c) 



