
401Basics of Microwave Tubes
This energy will completely return to the electric eld by the time the elec-
tron returns to the cathode. As noted at the end of Section 11.3.3, this case is
similar to that depicted by Equation 11.36 since only E and B are present. In
this case, the electron emerging from the cathode follows a cycloidal path. It
returns to the cathode or may fall into the anode as per the conditions noted
above.
ac eld present: In the presence of an ac eld, let
αω
ω ω
0
2
2
0
2
1
2−
=
(11.48a)
and
ω ω= 1 1.
0
(11.48b)
The substitution of Equation 11.48b in Equation 11.48a gives
α = =( ) .V V
1
/ 1 5
0
0 0
(11.48c)
Equation 11.48c obtained from ...