Imaging photomultiplier array with integrated amplifiers and high-speed USB interface

Multianode photomultiplier tube (PMT) arrays are finding application as convenient high-speed light sensitive devices for plasma imaging. This paper describes the development of a USB-based "plug-n-play" 16-channel PMT camera with 16 bits simultaneous acquisition of 16 signal channels at rates up to 2 MSs per channel. The preamplifiers and digital hardware are packaged in a compact housing which incorporates magnetic shielding, on-board generation of the high-voltage PMT bias, an optical filter mount and slits, and F-mount lens adaptor. Triggering, timing, and acquisition are handled by four field-programmable gate arrays (FPGAs) under instruction from a master FPGA controlled by a computer with a LABVIEW interface. We present technical design details and specifications and illustrate performance with high-speed images obtained on the H-1 heliac at the ANU

Comparison of hollow cathode and Penning discharges for metastable He production

The production of helium 21S singlet metastable atoms has been investigated using a hollow cathode discharge and a Penning discharge, under dc discharge conditions. The density of metastable atoms was measured by atomic absorption using the 21S-31P transition (501.57 nm). A range of plasma currents, varying from 16 to 180 mA, and a range of pressures, from 100 mTorr to 5 Torr, were investigated. This work is directed ultimately to the production of a supersonic metastable helium beam for plasma diagnostics, in particular the measurement of electric fields using laser induced fluorescence

Validation of collisional radiative modelling of emission line ratios for helium beam plasma diagnostic

A time-dependent collisional radiation model has been used to validate the use of a pulsed helium beam to measure electron temperature profiles in the H-1NF flexible heliac. The diagnostics technique is based on the measurement of helium spectral line ratios which are a strong function of electron temperature while being a weak function of electron density. The validation procedure involves comparing measured and calculated emissivities of spectral lines emitted by helium atoms as a function of position in the beam