No abstract

The electrical and mechanical setup for the pulsed gating of a microchannel plate (MCP) operating in the subnanosecond range is presented. Shaping of the plate electrodes as conductors of a strip transmission line allows voltage pulses of duration down to 400 ps to be propagated with negligible attenuation and distortion. This MCP mounting will be used as an x-ray image intensifier with very high temporal and spatial resolutions.

The time and space resolved neutron emission from a Filippov type dense plasma focus is measured with scintillation detectors associated with collimators, giving a one or two dimensional resolution. Axial and radial neutron emission distributions are obtained. Arguments are presented for the existence of two mechanisms producing the main neturon yield that takes place 100 nsec after the maximum compression. The former, belonging to a thermonuclear plasma (ne=3×1017 cm−3, Ti=7−8 keV, V=20 cm3) located in a region between 1 and 3 cm above the anode, lasts for about 40 nsec and accounts for 70% of the main neutron emission. The latter, due to beam-target interactions, takes place mainly near the cathode wall and produces about 20% of the main neutron output. A third neutron emission, uniformly distributed along the axis of the machine, is also present, accounting for 10% of the main neutron yield.

We describe in this paper a device giving time and space resolved soft x-ray pictures of rapidly varying intense sources based on the use of a channel plate intensifier. Ten nanosecond soft x-ray framing of a dense plasma focus has been obtained using a 200 μ pinhole for image formation limiting space resolution to 3 line pairs/mm. The principle of this device has been conceived in order to preserve the 10 line pairs/mm intrinsic space resolution determined by the channel plate.

No abstract