GUIDED-WAVE I'KOl'AdA TK ).\ TllKorciH ( i VU().MA(i XKTIC AIKDIA 589 



These results apply to stationary plasmas only. If the plasma were 

 an electron stream moving along the wave-propagation direction, for 

 example, the dielectric constants woukl depend on wavelength also, and 

 the propagation problem would he much more in\olved. 



The variations of e and 77 with a are shown in Fig. 2. e/eo for a given q 

 starts at 0- = 0, e = eo (1 — ^'), decreases through zero at o- = \/l — (f- 

 to — oc at 0- = 1 — 0, starts again from + co at o- = 1+0, and de- 

 creases to €0 at (T = 00 . 7j = when a = 0, decreases to — 00 at o- = 1 — 

 and then decreases from + x at 1 + to zero at o- = =© . 



"We note that similar formulae apply to the electron-gas in semicon- 

 ductors at temperatures sufficiently low and frecjuencies sufficiently high 

 so that damping is not important. However, the formulae have to be 



0.1 0.2 0.3 0.4 0.5 



Fig. 1(c) — The ratio ph = k/m versus a 



6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 

 (T 



