A direct electron bombarded charge coupled device for dynamic plasma imaging applications (abstract)

Abstract

A variety of plasma physics experiments require the recording of continuous time history of x-ray emission. Many laboratories have developed x-ray streak camera technology in order to time resolve x-ray spectra or images produced by laser-driven plasma experiments. These cameras record x rays by converting photons to electrons, which in turn are focused and swept across an electron sensitive area detector as a function of time. X-ray photons impinging on a transmission type photocathode generate photoelectrons which are accelerated to energies between 10 and 20 keV and focused onto a phosphor screen. The light from the phosphor image may be intensified using a microchannel plate, and is usually optically coupled directly onto film or an optical charge coupled device. We have designed and built an x-ray sensitive streak camera readout where we replaced the microchannel plate based intensifier and film package with a modified charge coupled device area detector to directly absorb accelerated photoelectrons emitted from the cathode. This system has been integrated into the streak tube arrangement. We will present a set of system performance data, which have been obtained from both bench top experiments on a dc source and dynamic measurements at the Nova laser facility. X-ray images at various exposure times show better spatial resolution, improved signal to noise ratio, and higher dynamic range. Other advantages include instantaneous data readout, which enables fast postprocessing, and no increase in overall cost for an engineered system.