High Current Density Advanced Cold Cathode Facility

Summary form only given. We report the design, construction and initial operation of an advanced, high-current-density, field emission cathode facility. The facility is designed to examine the nanophysics of field emission from advanced Al, C, CsI, Mo and other material cathodes that operate in the 1-1000 A/cm² regime. Operation is designed for UHV vacuum (10^-10 torr) and achieved with bake-out up to temperatures of 450 C to eliminate residual water vapor or other contaminants. The vacuum chamber is a stainless steel six-way cross. We use a scroll pump, turbo pump and a Vacion pump to achieve the UHV vacuum. We bake the system at 450 C for several days to eliminate contaminants inside. An optical fiber, pyrometer and spectrometer are used to measure the temperature of the cathode and possible plasma formation. An emitting tungsten filament is used to clean the anode surface. Both single tip and cathode arrays will be examined. The current-voltage characteristics including field emission, work function, space charge effects and the Fowler-Nordheim coefficients will be determined. A coaxial molybdenum anode is used to collect the electrons. One hundred volts will be applied between the outer and inner anode conductors to collect the electrons with large axial velocities. A high voltage supply is used to provide the 10 kV, 1-100 mus duration pulse. A set of high voltage probes are used to measure the cathode input voltage and current. Current monitors and a shielded resistor box in series with the anode are used to measure the wide range of cathode currents. Initial data for the first cathode will be presented