,
'
_
2.
REFERENCES
'
47
between the two spots of light is equal to four times the radins of
…
the electron circle.
The lament must be very close to the anode.
The Lenard equation (2—8) is used.
-
-
F. Magnetron Method: See
2—8.
A commercial mag—
netron or, for cruder work, a radio tube With cylindrical symmetry
may
be used.
Use co'mparatively high anode potentials to reduce
the effects of space charge and reverse the current through the
solenoid to correct for stray elds, such as that of the earth. The
radius of the anode may be measured, approximately, with a
cathetometer.
Equation 2—18_ is applied. Take values of H and
'
V when the anode current is about half way down the break.
Kirchner’r Modication of the WÏËCÎZ€TÏ Method: See section
2—4.
The principle of this method is outstandingly simple. The
author has used an accelerating potential of 250—350 volts, a
=
distance of 25 centimeters between deecting plates and a 15 meter
wave generated by a type
45 tube ina Colpitt’s circuit. See also,
'
Harnwell
and
Livingood,
“
Experimental Atomic Physics,”
'
page 130,
a
higher voltage arrangement with a magnetron
,
o$cillator.
_
'
.
,
REFERENCES
’
—
1.Lénard, Anh. der Physik., 51, 225 (1894).‘
2.
Ir. Frank. Inst., 202, 693, 721 (1926).
’
,
3. ]. ]. Thomson, Phil. _Mag., 44,
310, 318 (1897). _
,
‘
_
,
4. Lenard, Wied.
Ann. der Physik., 2, 359 (1900).
,
5. Wiechert, Anh.
739 (1899).
_
[
@.
975 (1931). , _
-
'
'
.
-,
7.’ÎaPerfy.andÿChafïètä,-Phy355Rev., 36,904 (1930);
_
‘
' _
,
'
.
(1937,)iL
_
;vÇ_®…
'
_
—
_,
.
f
*
‘
10See]BH°agProcïnstRad1°Eng—°>211132(1933)
,
%
11C1€et0nandWham8,PhV5R€V>50>1091(1936)
'Ï
_
—
12Th1smethodlspubhshedherefortherst tune (except formïme°
,
;:‘jÏ'
…
,“
iL.