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ELECTROMAGNETIC SEPARATION OF ISOTOPES IN A MAGNETIC FIELD. |
Let
us consider the beam of particles of mass m and of charge q which move with
equal velocity V. In a magnetic field B these particles are acted upon by a force
of Lorentz: F = (q/c)[V,B] (in Gauss system
of units). Under the action of this force the particle will
move in a circle path of radius R = (mc/qB)V. So, the particles of
different masses will follow paths bent on different radii. This principle
is used to separate the isotopes - the particles of the same charge, but a
little bit different masses.
Instead
of parallel beam of the particles moving with the equal velocity, we can
use paraxial beam of particles of equal energy. If the aperture of the beam is
rather small then after a half of the circle the particles will
meet in a
point. Before the particles enter the magnetic field they are
accelerated in a electrostatic field. If the potential difference is U,
then the velocity of the particles will be V=√2eU/m .
Moving in a magnetic field the particles will be acted upon
the force of Lorentz F = mV2/R = (e/c)VB.
From this equation we can find the radius of the trajectory R=(c/B)√2Um/q.
So, we can see that the distance from the slot (source of particles) to
the point of focusing is proportional to √m/q
. Width of the focus for every type of isotope δ = R·sin²(φ/2) ≈ Rφ²/4,
where φ
is the angle aperture of the particles beam.
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