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An electromagnetic particle-in-cell (PIC) code MAGIC3D is used for the computational analysis of the Ka-band coupled-cavity slow traveling-wave structure. The simulations from the hot-test showed that the 84-cavity Ka-band CCTWT produces 540 W of saturated output power at 29 GHz with an electronic efficiency of 8.1% and a gain of 28 dB when the beam voltage and current are set to 17 kV and 390 mA, respectively.

Results of computational and experimental studies of carbon nanotube (CNT) cathodes in gridded focusing guns are presented for traveling-wave tube applications. Results reveal that when the applied cathode voltage was -0.86 kV, both grid and annode are at ground potential, and the cathode-to-grid distance is 200 (mu)m, the dc emission current from the first gridded CNT cathode is measured to be 4.2 mA.

A linearized linear zed microwave power amplifier module (LMPM) consisting of a low-noise solid-state amplifier (SSA), predistortion linearizer, and low-gain helix-traveling wave tube (TWT) is configured to demonstrate both reduction of noise figure and suppression of high-order intermodulation distortion ratios. Both noise figure and intermodulation distortion (IMD) ratio are significantly improved compared with conventional helix-TWTs and microwave power modules.

The frequency locking and noise reduction in a self-injection-locked magnetron oscillator operating at 2.455 GHz is examined. Noise reduction is observed by more than 13 dB at 1 MHz offset and a frequency tuning bandwidth of 0.12 percent at a center frequency of 2.455 GHz.