Stabilized and Equalized Field-Emission Currents From Carbon Nanotube Emitters by Cascade Active-Current-Control

We have stabilized and equalized field-emission (FE) currents from carbon nanotube (CNT) emitters by a cascade active-current-control (ACC) using two transistors. Theoretical and experimental analyses on the cascade ACC operation, including single ACC with a single transistor, were done for both diode- and triode-configured CNT emitters. A fully vacuum-sealed CNT FE X-ray tube (FEXT) was used as a triode-configured test device. FE currents, in both configurations, by the cascade ACC were found to be stabilized to a standard deviation of 0.05% even in high-voltage and high-power circumstances while the single ACC could hardly regulate fluctuations in FE currents from CNT emitters. Furthermore, an array of CNT FEXTs successfully demonstrated a completely equalized emission current when the cascade ACC was employed. This result has important implications for FEXT current uniformity and other FEXTs applications, because the cascade ACC can equalize FE currents even through large variation of CNT emitters, thereby greatly enhancing the usability of FE devices.