Thermionic Emission Mechanism of a Novel Y2Hf2O7Ceramic Cathode Applied in High-Power Magnetron Tubes of Medical Linear Accelerator

In order to enhance output power and prolong lifetime of the high-power magnetron tubes of medical linear accelerator, a novel Y
2
Hf
2
O
7
Ceramic cathode had been developed. The thermionic emission characteristics of the Y
2
Hf
2
O
7
cathode had been measured. The experimental results show that the cathode can provide 3.5A/cm
²
current density for the space charge limitation at 1600 °C br under 300V anode voltage. At last, the thermionic emission mechanism of the Y
2
Hf
2
O
7
ceramic cathode had been researched by SEM, EDS and AES Analysis. The generation of the n-type semiconductor Y
2
Hf
2
O
(7-X)
is the reason which improved the emission property of the ceramic cathode.