REFLEX OSCILLATORS 



635 



0.9 



,0.7 



V 0.6 



O0.3 



VZZZZZZZZ^TZZ. 



\ ~ 



2.0 2.5 3.0 3.5 4.0 4.5 5.0 

 RADIUS OF TUBE, Tr, IN RADIANS 



Fig. 122. — Modulation coefficient for two semi-in finite tubes separated by a very small 

 distance, plotted vs the radius of the tube in radians. j3n is the modulation coefficient on 

 the axis, (3o is the average modulation coefficient and /3s is the root mean square modulation 

 coefficient, r is the radius of the cylinders. 



So = \IU{yr)', /3„ = 2/i(7r)/Tr/c(7'-), 

 ft = [1 - 7?(7'-)//o(7'-)]^ 



the form 



In this case, (b9) gives 



,r 1 . -1 2x 

 V — - sin — - 

 IT a 



0y or Br = F,(yd) = .h(yd/2) 



(b26) 



(b27) 



Both Fi{yd) and Fiiyd) are plotted vs. yd in Fig. 123. 



Figures 121, 122 and 123 cover fairly completely the case of slits and 

 holes. The same methods may be used to advantage in making an ap- 

 proximate calculation taking into account the effect of grid pitch and wire 

 size on modulation coefficient. 



Assume we have a pair of lined up grids, as shown in Fig. 124. Approxi- 

 mately, the potential near the left one is given as 



V ^ V[x/2 + (aV[/4Tr) 



•(/Sh 



2tx 



— COS 



2 Try 



(b28) 



