Field emission cathode device and method for forming a field emission cathode device

A field emission cathode device, comprising:

• a field emission cathode including a cylindrical substrate having a field emission material deposited on a cylindrical surface thereof, the field emission cathode defining a longitudinal axis;
• a solenoid extending concentrically about the cylindrical surface of the field emission cathode, and defining a gap therebetween, the solenoid defining opposed first and second open ends extending perpendicularly to the longitudinal axis;
• a current source electrically connected to the solenoid and arranged to direct a constant polarity (DC) current thereto, the DC current in the solenoid forming a magnetic field along the solenoid;
• and
• a gate voltage source electrically connected to the solenoid or the field emission cathode and arranged to interact therewith to generate an electric field inducing the field emission cathode to emit electrons from the field emission material into the gap, the emitted electrons being responsive to the magnetic field to spiral within the gap and about the longitudinal axis, in correspondence with the current flow in the solenoid, through the first open end of the solenoid.