A 3D-printed miniature magnetron gauge for ultra-high vacuum environments

Miniaturized magnetron gauges are necessary for monitoring vacuum level in miniature vacuum chambers. This paper addresses the challenges of designing the magnetron cavity and configuring the electric and magnetic fields within it while meeting the contradictory constraints of small size and high vacuum level that make electron confinement and accumulation difficult. The resulting gauge has an internal volume of 0.3 cm3 and is designed for and fabricated by advanced 3D printing - including direct metal laser sintering of 316 L stainless steel. Additionally, it is capable of directly attaching to a standard vacuum electrical feedthrough. A particle tracing simulation is used to assess the electron confinement for a range of operating conditions. Experimental characterization shows that the operating pressures extend from 10 nTorr (1.33 μPa) to 1 mTorr (133 mPa). The gauge current is repeatable over the characterized pressures at various values of supply source voltage, VS, from −1000 V to −2500 V, and ranges from ≈1 nA to ≈100 μA over these pressures and voltages. The effects of VS and pressure are examined and compared to prior work. This gauge is at least 30× smaller than commercially available magnetron gauges (e.g., a typical inverted magnetron transducer has an internal volume of 15 cm3).