The Electron Beam 60 kW System (EB-60) is a multipurpose device for studying the surface modification, thermal response, and failure modes of high heat flux materials and components. Targets of all shapes varying in size up to 30 cm by 60 cm can be tested. A large variety of ports and vacuum feed-throughs are available for diagnostics and utility connections. The electron source is typically a tungsten or tantalum filament with maximum operating parameters of 30 kV and 60 kW. Magnetic lenses and deflection coils are used to focus, position, and raster the electron beam to cover a variety of sample surfaces with a finely tuned or defocused beam. Various scenarios can be simulated with the electron gun since it provides a variable directed heat source. 2 ms up to continuous pulse lengths over heated areas from 1 to 100 cm2 are possible. The diagnostics of the facility are a TV monitoring system, an infrared camera and colorizing system, an array of optical and infrared pyrometers, a bank of imbedded thermocouples, strain gauges, a residual gas analyzer, and water calorimetry for actively cooled samples. Discharge and control of the electron beam gun as well as diagnostic control and data acquisition are carried out by a computerized data acquisition and control system. The post experimental analyses of high heat flux testing in the EB-60 involve many in-house capabilities. Data analyses involve the processing of recorded data such as the extraction of temperature contours using IR camera records or the comparison of thermocouple records over a series of tests. Processed data such as temperature profiles, mechanical responses, and thermal hydraulic results are compared with predictions from analytical models. After samples are removed from the EB-60 they are subjected to nondestructive and destructive analyses such as scanning electron microscope (SEM) surface studies and metallurgical cross sectioning for microstructural studies.
The Electron Beam Test System (EB-60) with maximum operating parameters of 20kV and 60kW.
The digital electron beam rastering system software was upgraded to allow for high-speed pattern switching. Dwell times for each pattern can be as little as 2 ms. These short dwell times are required for thermal shock and disruption experiments. Also, non-uniform heating patterns are possible and selected areas within the overall pattern can receive no heating. The digital system is functionally identical to the EB-1200 system and is capable of controlling pattern size and shape, as well as generating very complex raster patterns at twice the rate of the EB-1200. Patterns such as sine-filled, sawtooth-filled or triangular-filled rectangles, ellipses or trapezoids can be generated as well as arcs and TV raster scans with flyback. Other patterns include spirals, figure eights and concentric circles of various density gradients. The system is very flexible, because new patterns can be programmed into the pattern library as required. In addition, the operator may set the density or dwell time of each of 40 sections of a pattern. Some can have a higher heat flux and others can be nulled out entirely. Several separate processing sequences each consisting of as many as 10 individual steps (patterns) can be input by the operator to meet the requirements of an experiment.