130
6.
HIGH VACUUM, LOWNOLTAGE TUBES
is short when a strong magnetic eld acts upon slow electrons and
vice versa.
A short solenoid, placed axiallÿ With the beam, but covering
only a portion of its path, serves as a convergent lens
9 whose index
of refraction, like the magnetic eld strength, varies from point to —
point. In this case, electrons which diverge at a large angle from
the axis do not come to the same focus at those which travel more
nearlÿ along the axis and spherical aberration occurs.
.»
When electrons of various velocities pass between the charged
,
plates of a condenser, the slower ones are deected more than the
faster ones; ,the electrons are dispersed in a manner analogous tof—,
.Il
‘
' '
'
,
_——>——————>:
5
‘
.
and electron -raY analogS…
ÎhÇ'_‘dispersionç of“ various colbrs. of light as they pass througha
'Theusefç>f ÇlÇC'ŒO-‘SSŒÜÏC
for the purpose of converglng
than the use of magnet1€
_°°“SleratwnSIngureÔ—17Ô',aparallel ,
of electrons
Which°afrlesthempasttheballsSmœthoseelectronswmch
6.
HIGH VACUUM, LOWNOLTAGE TUBES
is short when a strong magnetic eld acts upon slow electrons and
vice versa.
A short solenoid, placed axiallÿ With the beam, but covering
only a portion of its path, serves as a convergent lens
9 whose index
of refraction, like the magnetic eld strength, varies from point to —
point. In this case, electrons which diverge at a large angle from
the axis do not come to the same focus at those which travel more
nearlÿ along the axis and spherical aberration occurs.
.»
When electrons of various velocities pass between the charged
,
plates of a condenser, the slower ones are deected more than the
faster ones; ,the electrons are dispersed in a manner analogous tof—,
.Il
‘
' '
'
,
_——>——————>:
5
‘
.
and electron -raY analogS…
ÎhÇ'_‘dispersionç of“ various colbrs. of light as they pass througha
'Theusefç>f ÇlÇC'ŒO-‘SSŒÜÏC
for the purpose of converglng
than the use of magnet1€
_°°“SleratwnSIngureÔ—17Ô',aparallel ,
of electrons
Which°afrlesthempasttheballsSmœthoseelectronswmch