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We find that the surface resistance of copper exceeds that predicted by classical electromagnetic theory. The small but significant discrepancy we find is consistent with results reported in adjacent frequency ranges. We will also present measurements of the reflectivity of rough copper surfaces and compare these results to theoretical predictions.
The growth of graphite film on copper foil by plasma enhanced chemical vapor deposition was achieved at the temperature as relatively low as 800Π. The obtained sample was characterized by SEM and Raman spectra. The results show that the transparent continuous graphite film can be obtained by PECVD.
Impregnated thermionic cathodes production was the main objective of this work. The W-30wt.%Cu composite was sintered by induction heating (1200°C). The porous matrix was obtained after decopperization (1600°C). High purity Ba-Ca aluminate was impregnated (1630°C). The amount of aluminate impregnated was 18.32wt.%. Microstructure, porosity, and particle sizes distribution were determined.
This paper reports on a diamond Brewster angle window which has been used as a vacuum barrier in a 140 GHz step-frequency tunable high power gyrotron. This configuration ensures operation of the gyrotron at different frequencies without reflection of the RF power and provides excellent material properties of CVD diamond in the mm wave range.
We present the hot test results of a 220 GHz, serpentine waveguide vacuum electron amplifier showcasing a novel embedded monofilament microfabrication technique based on UV-LIGA. The instantaneous operating bandwidth exceeds 15 GHz and the small signal gain of the circuit is over 14 dB. By varying the voltage slightly, an operating bandwidth of almost 40 GHz is realizable with a minimum circuit gain...
The U.S. Naval Research Laboratory has been developing a novel UV-LIGA process to create amplifier circuits from 100 GHz through the THz. A 670 GHz EIK ladder test piece has been successfully fabricated with a 0.004 inch diameter beam tunnel, and demonstrates sub-micron fabrication accuracies. The technique is being extended to showcase capabilities at 850 GHz, and 1.03, 1.35 and 1.50 THz.
The analysis for the parasitic mode excitation is performed for gyrotron beam tunnel. Scattering matrix simulations are performed for the initial design of the beam tunnel. Here only the symmetric TE modes are observed due to the week damping inside the tunnel. Various approaches are used for investigation of parasitic mode excitations.
We are developing a wideband 95-GHz, 200-W TWT powered by a 20-kV, 122-mA electron beam. The serpentine waveguide circuit is fabricated by UV-LIGA using an embedded monofilament, which produces an all-copper structure with beam tunnel. Simulations predict 37 dB small-signal gain and 245 W maximum output power.
In order to build an X-band sheet beam klystron with the peak output power of 5 MW, a high frequency structure has been designed through the three dimensional particle-in-cell simulations. The design method is consist of two steps, which are firstly finding a stable single-arm output cavity with the high energy extraction ability and secondly constructing a multi-cavity bunching section to produce...
A macro-focus X-ray tube with CNT emitters was successfully developed. An anode current of 1.15mA was collected when the copper grid gate voltage was 2.7kV. A very small x-ray focal spot size with less than 39μm can be achieved, which could potentially produce very high special resolution X-ray image.
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