PRODUCTION ENGINEERING MEASURE FOR LOW FIELD MAGNETRON BL-234C

摘要

The first five engineering tubes have been delivered in accordance with contractual requirements. These tubes are essentially similar in design and process¬ing to the BL-234 tubes prior to initiation of this contract. Two tubes from this group were selected by Harry Diamond Laboratories, tube numbers 4S and 5S, for life test at their location. It was reported that 4S was operated 38 hours and 5S operated 22 hours before the testing was terminated because of excessive jitter. Four of the five tubes have been returned to Bomac where a life test has been initiated on tube 3S.nThe cathode investigation during this quarter has focused on two major cathode types;the presently used nickel matrix cathode and the longer life "S" type tungsten dispenser cathode. The first two tubes completed for the next group of five tubes to be delivered in November have nickel matrix cathodes. One cathode was fab¬ricated by Bomac and the other by Semicon Associates. Tube 6S, which contains the Semicon nickel matrix cathode, delivered 900 peak watts of power with low jitter and 350 volt mode width. Tube 7S, containing the standard Bomac nickel matrix cathode, produced 600 watts with a 550 volt mode width and low jitter. The exceedingly good performance of these two tubes is essentially attributed to a change in cathode activa¬tion procedure.nA tube has been processed to include a directly heated tungsten dispen-ser cathode constructed by Spectra-Mat, Inc. Although problems were encountered with erratic heater operation during hot test, the heater power requirement of these cathodes is only l/6th of that of the present indirectly heated design.nA method of finish machining a hot hobbed anode by conventional tech¬niques as opposed to the present EDM, electrical discharge machining, has been achieved. This method consists essentially of potting the anode in a plastic compound, rough machining the anode end cavities with an end mill, finishing with a carbide bor¬ing bar, and broaching the anode hole with a modified broach.nIt has been determined that subjecting the potted anode to vibration hardens the copper and permits an improved anode finish as well as a reduction in the size of burrs produced by conventional machining. Work hardening by temperature cycling was also investigated, but no indication of copper hardening was observed.