The major areas of work completed during this reporting period are summarized below.nKu-Band TubenA total of eleven tubes were built and RF tested in the solenoidnto evaluate the vacuum envelope design.nA broadband noise figure of less than 9.8 db was measured fromn10.5 to 16.5 Gc in 900 gauss solenoid field.nA minimum noise figure of 7.3 db was achieved with the tubenoptimized in 1000 gauss solenoid field.nA good helix design was achieved with low van helix supportednby 0.02 i-inch diameter ceramic rods. This helix structure gave the least dispersion and the flattest broadband small-signal gain to date. A small-signal gain variation of 1.5 db was ob¬tained.nThe initial PPM-focusing structure gives a gun field of 900 gaussnand a stack field of 1000 gauss. This is obtained with 0.625 OD x 0.375 ID x 0.150 inch thick Alnico VIII ring magnet operating around the maximum energy point on the demagneti¬zation curve, and with 0.625 OD x 0.157 ID x 0.050 inch thick Armco Iron pole pieces. With this structure, the a parameter that determines the beam rippling is on the order 0.225, which Is below the maximum a value of 0.25.
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