Investigation of a spherical oscillator ionization gauges with carbon nanotube field-emitter cathodes

Nowadays, the sensitivities of the ionization gauges with carbon nanotube (CNT) cathodes are generally low, which is unfavorable for the measurement of extremely high vacuum (XHV). In order to solve the problems, a spherical oscillator gauge with CNT cathode, which has high gauge sensitivity, is simulated using SIMION 8.0 and experimented preliminarily. The numerical simulation results show that the parts of emission electrons from the CNT cathode are blocked by the gate electrode, and electrons through the gate electrons are focused by focusing electrode. More than 90% of the electrons enter into the ionization zone, which reciprocate oscillation motion, and the single electron oscillation trajectory length of ∼1000mm. It is found that the spherical oscillator gauge with CNT cathode responded linearly to the pressure in the range from 8.7×10
⁻⁶
to ∼10
⁻²
Pa, and a sensitivity of ∼0.03 Pa
⁻¹
under an anode current of 7μΑ was achieved for air. The power consumption of the gauge was less than 0.1W, which is especially suitable for space exploration applications.