Nano Vacuum Channel Transistors (NVCT)

The goal of Nano Channel Vacuum Transistor (NVCT) research is to develop and characterize three-terminal vacuum transistor devices that operate in ultra-high vacuum (UHV) and withstand temperatures up to 400 °C. The transistors consist of an insulated gate, an emitter array, and a collector. To avoid overheating the collector, the gate is pulsed from 0 to 40 V at a duty cycle of 10-20% while the emitter and collector are fixed DC voltages of 0V and 100 V, respectively. Current from emitter to collector is measured to obtain an output current – input voltage plot (I-V curve). The devices are heated using a molybdenum chuck inside the UHV chamber. After preliminary tests, the devices are moved to the UHV lifetime test chamber and run with pulsed gate voltage with fixed amplitude at constant temperature for hundreds of hours. Periodic IV sweeps are also conducted to observe changes. Factors such as overheating and arcing can lead to device degradation or failure. The goals of the project include designing driver systems for the devices, implementing automated Data Acquisition (DAQ) hardware to control and monitor testing systems, and using data to characterize the devices and determine approximate lifetime, maximum operating conditions, and failure conditions

Study of Electron Instabilities in Crossed Electric and Magnetic Fields

Crossed-field devices such as cross field amplifiers (CFA) are used in high power radar systems. In our research of cross field devices, electrons are injected into a crossed electric and magnetic field planar structure to observe the physical behavior within the system. The objective is to design and implement electronics to drive Gated Field Emission Arrays (GFEA) that have been fabricated by collaborators at MIT. This experiment will assist with the observation of electron behavior in the crossed-field vacuum environment. Understanding of the onset of electron beam instability in crossed-field devices is not complete. A predesigned controller board is used for electron injection device control to regulate high voltage, and current. An ATXMEGA192A microprocessor on the controller board is responsible for managing much of the input and output data. LABVIEW software communicates to this controller board and will be used to observe and record data for further analysis. Components such as opto-isolator boards, current monitor boards, and an isolation box will ensure the safety of both researchers and hardware

Study of Electron Instabilities in Crossed Electric and Magnetic Fields

In the research of Cross Field Devices we observe the behavior of injected electrons within a planar crossed-field structure. The objective is to design and implement electronics to drive the Gated Field Emission Arrays (fabricated at the Massachusetts Institute of Technology) that are used to generate up to 150 mA of electron current into our structure. In preparation for testing, an isolation box is assembled to ensure high voltage safety. This requires testing of a previously designed Opto-Coupler circuit board to ensure hardware protection. Another previously designed circuit that must be implemented is an ARC detection circuit to monitor discharges in the Gated Field Emitters and ensure a system shut down to prevent further damage.The future applications of this research will assist with development of high power microwave amplifiers and oscillator used in radar and communication systems