A study on attenuation process of C-C composite material electron beam diode cathode plasma via 12 framing camera

An experimental study of the intense current electron beam diode with a foil-free annular C–C composite material cathode is carried out, the attenuation process of cathode carbon ions at different axial magnetic fields is acquired using an ultrahigh speed 12 framing camera, and the attenuation characteristics of cathode plasma under different discharging voltage waveforms have also been studied. The experiment results show that with the increase in the magnetic field, the force of the axial magnetic field on the electron beam becomes stronger, and the spatial distribution of the Cherenkov radiation light, which is generated by the electron beam bombarding the observation window, decreases. Meanwhile, if the axial magnetic field is less than 0.46 T, the cathode carbon ions have disappeared before reaching the anode. When the axial magnetic field is greater than 0.46 T, the cathode carbon ions move to the anode and then disappear in the vicinity of the anode. A rough estimate shows that the axial diffusion velocity of the cathode carbon ions is about 1.94 cm/ μs. In addition, if the discharging voltage waveform has a kickback positive voltage, the carbon ions will diffuse rapidly in the radial direction.