PRODUCTION ENGINEERING MEASURE FOR LOW FIELD MAGNETRON BL-234C.
Quarterly progress rept. no. 2, 28 Jul-28 Oct 65,
BOMAC DIV VARIAN ASSOCIATES BEVERLY MASS
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The cathode investigation was focused on two major cathode types the presently used nickel matrix cathode and the longer life S type tungsten dispenser cathode. 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 activation procedure. A tube has been processed to include a directly heated tungsten dispenser cathode. Although problems were encountered with erratic heater operation during hot test, the heater power requirement of these cathodes is only 16th of that of the present indirectly heated design. Finish machining a hot hobbed anode was achieved by potting the anode in a plastic compound, rough machining the anode end cavities with an end mill, finishing with a carbide boring bar, and broaching the anode hole with a modified broach. It 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.
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