A W-Band Backward Wave Oscillator Based on Carbon Nanotube Cold Cathode

High-frequency, fast response, and room-temperature operation are vital trends and challenges for vacuum electronic devices (VEDs), especially in the millimeter-wave and terahertz range. This study proposes an electrically stimulated cold-cathode high-frequency oscillator capable of generating millimeter-wave single-frequency electromagnetic waves. A W-band backward wave oscillator (BWO) was developed by utilizing a carbon nanotube (CNT) cold cathode in conjunction with a double-staggered grating (DSG) slow wave structure (SWS) in high-order overmoded, which offers notable advantages, such as rapid response time, operating at room temperature, and compact dimension. The emitted sheet electron beam from the CNT cold cathode serves as the electron source, interacting within the SWS to stimulate TM $_{\text{21}}$ -like mode oscillations, thereby generating high-frequency electromagnetic waves. Experimental results validated the feasibility of the operating principle, resulting in the generation of output electromagnetic wave signals at 96.316 and 100.045 GHz. This design and principle can find applications in high-frequency cold-cathode vacuum electron devices.