RADIAL BEAM VACUUM TUBE 



193 



B 



Fig. 3. — Electron trajectories made visible with a small amount of gas. A. — Magnetic 

 field lined up with active spots on the cathode. B. — Magnetic field at 45° with respect 

 to the active spots. 



cycloid-like paths along the cathode, moving up on one side and down on the 

 other. 

 The photographs of Fig. 3 showing the trajectories were obtained by 



