A 400 kV electrostatic energy analyzer for the TEXT-upgrade 2 MeV heavy ion beam probe

Summary form only given. A 2-MeV heavy ion beam probe with two primary beam lines and two secondary beam detectors, presently under construction, will be used to measure the space potential and to determine the fluctuation characteristics in the TEXT-Upgrade diverted plasma during the anticipated H-mode operations. A Proca-Green-type electrostatic energy analyzer requires that 400 kV be held on a large (150-cm×40-cm) plate across a 20-cm vacuum gap. Such a high voltage on a large electrode may be difficult to maintain for an adequate period of time. Besides being large, the high voltage plate is designed so that it is 90% transparent to UV radiation which can be detrimental to the measurements. This requirement may cause additional problems when high voltage is applied to the electrode. In order to identify the problem that might arise in this particular high-voltage environment. an electrode structure identical to that of the actual analyzer is being built for testing purposes. If the high-voltage tests indicate that the Proca-Green analyzer is not feasible for analyzing a 2-MeV beam, a different kind of analyzer which requires a lower voltage will be used