1 d 



d'^W 



p dz \ dz- 



n I - n 



1 d (dp (flV 



— W — '- 



o dz\dz "" dz 



1 ±- 



k 2 



Cw^ + 0J„) 



(51) 



r w '1 + —2^ ^ - 2. ^ _ w 



"' rfz ' /.„2 dz dz "' d.^2 



1± ^ I ^^o„ ± CO J 



gT 



2 C rf, ] 2 dz I-'"- "' "'"- " 



aj„ + co_l ;t |/?„, ±/?. 



/e„-^ c/2 dz 



(52) 



THE SECONDARY WAVE FIELD IN THE RESONANCE CASE 



The secondary wave field is given by (36) to (38), which with (49) and (50) 



read 



2,J2) 



d^W 



"^hi-ZT-srw'^'U 



4,„(2) j3,„(2) 



d\' 



w'^' 1 



dz^dt 2 dt 2(92 



rzll^L'^'^A' 



(co^tcojt 



(53) 



3,„(2) 



dt^dz 



-gV,2,(2)^^ ^^G,^,,(0)sm|( 



at 2 = 



«)'2) = at z = H 



(55) 



where either the plus or minus sign holds. If eigenvalues of (53) exist, which 

 fulfill the condition 



ir ±r|2 



m fil 



(56) 



17 



