The Electron Experiment on AMPTE UKS

The AMPTE UKS electron experiment measures count rates of electrons within the energy range 6 eV to 25 keV. Two sensors are positioned so that during each spacecraft rotation (~5-s period) electrons from all directions are detected. The experiment is divided into two halves, which are identical apart from their viewing directions. Each half consists of a sensor, which includes an electrostatic analyzer and a microchannel plate, a high-voltage generator, and a microprocessor controller. The experiment has many modes of operation, all available for selection in real time directly by the experimenters. The two halves of the experiment can be operated independently, although they normally operate in the same mode. Apart from controlling the mode parameters, such as energy range, energy scan rate, energy levels per scan, etc., the microprocessor is used to compress, logarithmically, the count rate into a form suitable for transmission using 8-bit words, and to act as the telemetry, data, and command interface between the experiment and the spacecraft. The experiment is also used as an input stage for the particle-correlator experiment (see this issue) on AMPTE UKS. A sample of the real-time data showing bow shock and magnetopause crossings is presented.