Hua Huang

High power operation of an X-band coaxial multi-beam relativistic klystron amplifier

An X-band coaxial multi-beam relativistic klystron amplifier is designed in order to increase output microwave power and operating frequency of the amplifier tube. The experiment is performed on a Tesla-type accelerator. The amplifier is driven by an electron beam of 2.8 kA at 720 kV, and a microwave power of 30 kW and frequency of 9.384 GHz is injected into an input cavity by means of an external source, then a microwave power of over 800 MW is extracted, the amplifier gain is about 44 dB, and conversion efficiency is 40%. The experiment proves that output power of nearly GWs can be generated with the X-band coaxial multi-beam relativistic klystron amplifier driven by a kW-level input power.

Investigation of an X-band gigawatt long pulse multi-beam relativistic klystron amplifier

To achieve a gigawatt-level long pulse radiation power in X-band, a multi-beam relativistic klystron amplifier is proposed and studied experimentally. By introducing 18 electron drift tubes and extended interaction cavities, the power capacity of the device is increased. A radiation power of 1.23 GW with efficiency of 41% and amplifier gain of 46 dB is obtained in the particle-in-cell simulation. Under conditions of a 10 Hz repeat frequency and an input RF power of 30 kW, a radiation power of 0.9 GW, frequency of 9.405 GHz, pulse duration of 105 ns, and efficiency of 30% is generated in the experiment, and the amplifier gain is about 45 dB. Both the simulation and the experiment prove that the multi-beam relativistic klystron amplifier can generate a long pulse GW-level radiation power in X-band.

Analysis and Simulation of a Multigap Sheet Beam Extended Interaction Relativistic Klystron Amplifier

To improve the output power and electron efficiency and broaden the operating bandwidth, the three-gap extended output cavity was used in the relativistic klystron to replace the single-gap output cavity. The high-frequency characteristics of the three-gap extended cavity were studied. The electron load conductance was derived and corrected based on the theory of relativity, by which a more accurate relation of electron load conductance versus transmit angle can be obtained. The characteristic impedance is three times bigger than that of the single-gap cavity under the case of the 2π mode, which can improve the M2(R/Q) and the beam-wave interaction efficiency. The model of sheet beam klystron (SBK) is comprised of three-gap input cavity, two-gap first idler, three-gap second idler cavity, and three-gap output cavity. The 3-D particle-in-cell simulation results show that for a 500 kV, 1 kA, 40.134 GHz, and 20 W input power, the SBK is capable of generating an output power higher than 142 MW with the gain of 68.5 dB, maximum interaction efficiency of 28.4%, and 3-dB bandwidth of 240 MHz.

Design of an \(X\) -Band Gigawatt Multibeam Relativistic Klystron Amplifier

To achieve gigawatt-level amplification output radiation in X-band, an X-band coaxial multibeam relativistic klystron amplifier is designed. When the diode voltage and diode current are increased to obtain higher output power, higher modes can seriously degrade Klystron performance and cause pulse shortening. Special measures are introduced in the device to suppress the higher mode excitation and avoid pulse shortening. Finally, pulse shortening is avoided in the coaxial multibeam relativistic Klystron amplifier. Output power of 2.1 GW with an efficiency of 40% is obtained in the particle-in-cell simulation when driven microwave power is only several kilowatts.

Investigation of a Ka-Band High-Power Sheet Beam Relativistic Extended Interaction Oscillator

The sheet beam relativistic extended interaction oscillator (REIO) is a very important high-power millimeter-wave source for many actual and potential applications. A Ka-band sheet beam REIO is designed by means of particle-in-cell (PIC) simulation. In the design, we adopt a sheet electron beam with dimensions of 45 mm

Extended interaction oversized coaxial relativistic klystron amplifier with gigawatt-level output at Ka band

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Study on Ka-Band Sheet Beam Traveling Wave Tube Focused by Closed PCM

mm to reduce the space charge effect and the extended interaction cavities to increase the power capacity. The results of the PIC simulation demonstrate the device can generate an output power of 404 MW at 30 GHz with an efficiency of 20%. In addition, we develop the experiment on a short-pulse accelerator. In the experiment, the oscillator generates a millimeter-wave power of 125 MW with a beam current of 4 kA, a beam voltage of 500 kV, and guiding magnetic field of 1 T. The frequency of the output millimeter wave is 30.6 GHz and the pulsewidth is 16 ns. The experiment proves that millimeter wave of over 100 MW can be generated with the sheet beam REIO.

Microwave power synthesis method

In this paper, an extended interaction oversized coaxial relativistic klystron amplifier (EIOC-RKA) with Gigawatt-level output at Ka band is proposed. We introduce the oversized coaxial and multi-gap resonant cavities to increase the power capacity and investigate a non-uniform extended interaction output cavity to improve the electronic efficiency of the EIOC-RKA. We develop a high order mode gap in the input and output cavities to easily design and fabricate the input and output couplers. Meanwhile, we design the EIOC-RKA by using the particle-in-cell simulation. In the simulations, we use an electron beam with a current of 6 kA and a voltage of 525 kV, which is focused by a low focusing magnetic flux intensity of 0.5 T. The simulation results demonstrate that the saturated output power is 1.17 GW, the electronic efficiency is 37.1%, and the saturated gain is 57 dB at 30 GHz. The self-oscillation is suppressed by adopting the absorbing materials. The proposed EIOC-RKA has plenty of advantages such as large power capacity, high electronic efficiency, low focusing magnetic, high gain, and simple structure.In this paper, an extended interaction oversized coaxial relativistic klystron amplifier (EIOC-RKA) with Gigawatt-level output at Ka band is proposed. We introduce the oversized coaxial and multi-gap resonant cavities to increase the power capacity and investigate a non-uniform extended interaction output cavity to improve the electronic efficiency of the EIOC-RKA. We develop a high order mode gap in the input and output cavities to easily design and fabricate the input and output couplers. Meanwhile, we design the EIOC-RKA by using the particle-in-cell simulation. In the simulations, we use an electron beam with a current of 6 kA and a voltage of 525 kV, which is focused by a low focusing magnetic flux intensity of 0.5 T. The simulation results demonstrate that the saturated output power is 1.17 GW, the electronic efficiency is 37.1%, and the saturated gain is 57 dB at 30 GHz. The self-oscillation is suppressed by adopting the absorbing materials. The proposed EIOC-RKA has plenty of advantages such as la...