Eur. Phys. J. Plus (2022) 137: 615
https://doi.org/10.1140/epjp/s13360-022-02817-1

Regular Article

Fabrication and enhancement of a new high-current density scandate electron emitter for a pulsed Pierce electron gun

Department of Physic, Payame Noor University, P. O. Box, 19395-4697, Tehran, Iran

^a agharaati@pnu.ac.ir

Received: 6 April 2021
Accepted: 9 May 2022
Published online: 21 May 2022

Abstract

One of the ways to increase the current density of microwave tube electron guns is adding Sc₂O₃ to the composition of the cathode electron-emitting materials (EEMs) which makes the difference in the manufacturing and hot test processes from M-type cathodes. The constructed optimum composition of the EEMs for the new scandate cathode or Sc-cathode is 5:0.95:1.1 with 2.9% Sc₂O₃ respect to the total weight of the EEMs. For fabricating this cathode, in comparison with an M-type cathode with a 4:1:1 stoichiometry, the key difference is finding the melting and penetration cycle of EEMs. For Sc-cathode, the temperature and melting cycle duration, (1750 °C, 270 min Vs. 1650 °C, 262 min) and the temperature and penetration cycle duration, (1800 °C, 54 min Vs. 1650 °C, 43 min), are greater than the M-type cathode. Two types of spherical cathodes were fabricated and tested after simulating in a diode electron gun (DEG) Pierce type. The simulation process is almost identical for both, but the output of the hot test process is different. Finally, it is concluded that using the newly fabricated Sc-cathode, in pulsed mode and with the conditions of %1 duty cycle, 2 mm anode–cathode distance, 10 kV anode–cathode potential and 950 °C_B, a high-current density of 55 A/cm² can be achieved, which is 4.78 times greater than the M-type cathode in the same condition. Finally, the new cathode is compared with the Sc-cathode that made by others and it is concluded that the performance of the new cathode is acceptable.