High voltage power supply for a small plasma spectrometer

Abstract

This thesis describes the design, manufacturing, and testing of a high voltage power supply for an electron spectrometer to be used on a small spacecraft. The challenge was reducing complexity, size, and power consumption enough to be useful for a CubeSat or a sounding rocket sub-payload. The power supply has two purposes: i) it produces DC at roughly 2000 V for a microchannel plate detector and ii) it produces exponential voltage sweeps from about +4000 V to below 5 V for an electrostatic analyzer. This power supply uses solid state relays for a charge pump and for producing voltage sweeps with capacitive discharge. The detector power supply is software and hardware regulated to provide tunable output up to 2400 V, with voltage drift and ripple of around ±1%. The power supply is managed by an MSP430 microcontroller. It includes several automatic, hardware-based, closed-loop controls to stabilize performance across a range of temperatures, input voltages, and component parameters. All digital switching, signal changes, measurements, and monitoring are done in a single control loop. The design includes thermal protection, current limiting, a hardware watchdog, transient voltage suppression, and hardware-based overvoltage protection. The circuits survived thermal vacuum testing, operating within specifications for several weeks during many cycles of -40 °C to +70°C. The supply operated a real spectrometer inside an electron beam chamber. The consistent voltage sweeps allowed the spectrometer to accurately distinguish electron beam energies. This power supply is a successful proof of concept for powering a microchannel plate detector and an electrostatic analyzer at over 4000 V using a single 64 mm diameter circuit board, consuming 0.5 W or less from a small spacecraft.