Figure 12. Electron path in drift tube.
striking the sides of the drift tube. Once the electrons enter the drift tube they are no longer under the accelerating
effects of the cathode-to-drift-tube potential. The electrons will then coast or drift at a constant velocity until they
encounter the electric field across the gaps of the resonant cavities along the length of the drift tube.
f. The axial magnetic field produced by the body coil assembly (fig. 13 ), extends the length of the drift
tube assembly. The electrons in the drift tubes travel parallel with the axial magnetic field. It is impossible to get
the degree of focusing required to prevent all the electrons from being directed from the beam and striking the
walls of the drift tube. However, by proper adjustment of the magnetic body coils, it is possible to keep stray
electrons to a practical minimum.
Figure 13. Magnetic coils.
344 L1
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