BSTJ 30: 4. October 1951: A Gun for Starting Electrons Straight in a Magnetic Field. (Pierce, J.R.)

1.6 MB·English

‘A Gun for Starting Electrons Straight in a Magnetic Field
yy prance

tut a lest poner Ste sip a ai

N 1051 Davawe ae! Calbiee show! that cular aperce in om
cucting plate which separates regione wid diferent erie gracents
‘owpal tthe sefaces act 2 an let Les of focal length Pen by
we

ae o

ese ¥ isthe potential of the plate with respect to the eathade which
supplies the lotraae and and Vane the chr raents onthe fet
nd pet ses of the aertice respectively

‘Wher an cletnas ur x predneet Bp eau pla rath aod 2
oppnee' pla patie aperirel ade the Akshar
(ue Foratastiversing lon are cause th emerging hon to spend Someta
Dis cuty waledeabe. A strong lly stagnate eld parle = che

litt cles fw may be yee to reduce sul grating oe Beam,
as wll 2 the spreading ecu iy spre enarge al by Darna voorten

The maguete ch cis a complesiyoveteonn: Hie wien oF ne
lhoam eousd by the lens action ofthe ena apetir, for he iil velace
ites whien the letras hive emerging fot Une aperture case then To
spiral inthe mec fli nnd the Beat pusducsl iv altemately narrow
Set mat along ite lest,

This paper desis ap election gun wonssting of cathode and the
sported plates tnester with a alions axl mvt eld, The go
Afesigne so thet tert lene on ero andthe lato rere train
ferae.t0 the camede fe

Tre aletnale syste is shows in Hig. 1. Tae elernonstrvel frome the
plas cathode the apertre in lane sectede yin parla nes, Att
they aecive weal oesity appnovimasely a, yven iy

Dax J. Cais enon Lea Ps Sey vl 88 88, Aa
825 Thr we, sveme THIER, OCHOMER 1951

ore ris the radial postion othe weseo, the fra en af she lens
st fy ands isthe longevity at

2
|

rq. 1the gm seri a plan the god vo pert pan dete
EE UE acne ad Eee i re \atbed oli tn sors

geht

he magnetic Hel stength iss ajusted as vo evturn the elcirons to
the mains at As Figure 2 stow the motion of ar outer electron between
“Avan seen looking slau the ai ince there no eal electric eld
ki POR STARTING ELECTRONS STRATORT 1 MAGEE FL 827

betwen Ay tl Ay, the electron will ove i err ac of some edius
tnd at Ay the mca velocity will le must and opposite to thet et 13
th by iil Be
‘The change in radia! velocity al the eetron in pesing tzoush che
apertae iy Si

mons i)

snbere Mes the fal engl of the lone at ay and te the lngitnal
‘leeteon velocity xt snd suck that

feo @

ence, Ue rai very on of Ce apposing etre overcome
Sn puting through ne apartore in sand eerie ove pl che
ato the it of ae
For ermpertare di enon xl wall pce hae, we may ese
a unform rato betwen the ethene and bewece al
Farber, we ay ie the elation
win Via 6
From (0-8) we ely find tht the equi sltionItneen fy thee
ig rom athe clyde ecg Uren ts tae ae
‘he potentials of 4s Ny wilh wet tothe cate,
Like TT + N=
Th cas ofsgucoclangelinital emis, the space charge wil cause the
again tothe of Ao he} times a rest ti esata of ce
Charge, pce cane i len ne scent is rego ely, Err
Otte om (al be mpd by
‘We hvestl to dete the maga el eure ost eh ke
toon leaving yates tothe ran vat
Pht Fig 3 nae that there tore ecogh an angle Since the
nls veloc of tone magi ld ei,

2 = elma a

wher isthe transit time between and J

As the electron moves betwcen yan > mits constant acelnation
82k ns wrts exenea wwrwnmeAL ONAL, OFTORR 1951

(Ni, fom Fig, 2 we oe alo that

rasin@/2) ~ ring? 9/2) — rexet0P2)
ten 82) — ew

Now
-9

san fo — /2) = he
°

Ian (822) = = ie

For sitctlar motion will a angular ylocly (elas and = sie
eal speed # ta oy tbe ew men ys

ra = lef an

ig, tl Ll of taco ae

ei ae gested oo ‘anton ati vllce

ran), , ) ane a)

rm (ad (8) we se tha i uy Be sen

tan =

4
ww) , Sn
8 VI

ve

= 1 = s(0/tangey2 an

‘We mote thet mst le in the thd fourth gparaes. Ta Fig 3, 6
atin ve. PP
Wennow have both Ly and expressed in terns V/s (0) al (11),
‘om # and £ we can usin the proper value of F fom (1) ae £8

B= Bile
B= OT ileal + VYIVD a
We sce foe Fig. 4 iat. Ler wl be Bit errr in sssming that © =
Tr we assume carplets space charge between the eattde and a, aad
ree spe charge betwosn and ly, BOehng altered sve he tho
Eri Tye a8 was exphined previously, this becomes {tines the valuo given
we.
Ti Be ee af lite Ss he sme fomeson of Ya for apertures
the corection far space charge ie the some, ent (£2) wi give the cotect
magnetic ld ith =