A design for making a new simple coil trap | ||||||||
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It seems that for some applications we require to decrease the
drifting velocity of atomic or molecular beams, and seemingly
various methods have been designed to achieve this purpose. I
propose to select a relatively big coreless solenoid through which
we can give an intense direct (probably impulsive) electric
current. Set the whole instrument which is to create the beam in
the space interior to the solenoid, and create the beam parallel
to the solenoid. There is no magnetic field gradient inside a
current-carrying solenoid. So, the drift velocity of the beam is
not changed inside the solenoid, but when it is leaving the
solenoid its drift velocity decreases. (If we use this method
conversely we can increase the drift velocity of the beam.)
Since the effective decelerating region at the opening
of a current-carrying solenoid is not so long, it seems that use
of cone or (half) saddle-shaped solenoids can extend the effective decelerating region properly,
and, depending on the intensity of current, increase the intensity
of the magnetic field gradient.
(33) A design for making a new simple coil trap (pdf)