Extended Interaction Oscillator Research Articles

High-efficiency terahertz-wave generation based on extended interaction oscillator with strongly-coupled 2π mode operation

A slow-wave structure improvement for enhancing the 2π-mode electronic efficiency is embodied in the validation of an extended interaction oscillator (EIO), which has an electronic efficiency of 6.52% at 0.22 THz from particle-in-cell (PIC) calculations. A 2π-mode bi-periodic slow-wave structure (BPSWS) with staggered long and short slots is utilized for optimizing the circuit performance. The proposed BPSWS has the capability of combining the respective advantages for both π and 2π-mode in terms of coupling performance and output performance, thus supporting a strongly-coupled 2π-mode with higher coupling capability. Compared with the typical mono-periodic SWS (MPSWS), the adopted strongly-coupled 2π-mode effectively improves the characteristic impedance M2R/Q by 103% to 66.79 Ω, the coupling coefficient by 66% to 0.497, and the normalized wave-amplitude by 22%. Accordingly, 503 W of average output power can be derived for the BPSWS-EIO with a 25.7 kV and 0.3 A sheet beam injected. Cold-test experiments were conducted, confirming that the 0.22 THz structure exhibits commendable fabrication precision and consistency and thus demonstrates the expected frequency response.

Design and Experiment of a Sheet Beam Gun for Extended Interaction Oscillator

Design and Experiment of a Sheet Beam Gun for Extended Interaction Oscillator

Power Enhancement of 0.22-THz Extended Interaction Oscillator Based on Orthogonal Interconnection Structure With Output Coupler

Power Enhancement of 0.22-THz Extended Interaction Oscillator Based on Orthogonal Interconnection Structure With Output Coupler

Novel E-Shaped Waveguide Relativistic Extended Interaction Oscillator With Low Magnetic Field Operation

Novel E-Shaped Waveguide Relativistic Extended Interaction Oscillator With Low Magnetic Field Operation

Efficiency Enhancement of a Millimeter-Wave, Two-Beam Extended Interaction Oscillator Based on All-Period Field Optimization

Efficiency Enhancement of a Millimeter-Wave, Two-Beam Extended Interaction Oscillator Based on All-Period Field Optimization

A Terahertz Broad Compound Tuning Range Extended Interaction Oscillator Operating at Quasi-TM51 Mode

A Terahertz Broad Compound Tuning Range Extended Interaction Oscillator Operating at Quasi-TM₅₁ Mode

Study of a 0.3-THz Extended Interaction Oscillator Based on the Pseudospark-Sourced Sheet Electron Beam

Study of a 0.3-THz Extended Interaction Oscillator Based on the Pseudospark-Sourced Sheet Electron Beam

A Novel 2-D Slotted Structure Extended Interaction Oscillator

Numerous vacuum electronic devices (VEDs) have been widely studied, among which extended interaction oscillators (EIO) exhibit appealing characteristics, such as high frequency, high efficiency, lightweight, low working voltage, and stable working frequency. The slow wave structure typically adopts the coupled-cavity, folded-waveguide, ladder line, and other structures. The ladder line has a simple structure and is easy to process, with desirable heat dissipation and large power capacity. In this study, a novel slow wave structure being longitudinally slotted in the transverse grating of the original ladder line is proposed, and the 2-D slotted structure can be obtained. Encouragingly, the structure not only increases the cross-sectional area of the electron beam but also, more importantly, increases the effective interaction area to considerably improve the output power. The dispersion characteristics and field distribution are first studied through numerical and simulation calculations, and the optimal slotted structure parameters and working parameters are analyzed using PIC software. Next, a 94-GHz 2-D slotted structure EIO is designed. Finally, compared with the ladder line, the cavity characteristic impedance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{R}$</tex-math> </inline-formula> / <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{Q}$</tex-math> </inline-formula> is increased by 52.5%, and the output power is increased by 21.1%. This novel structure is expected to provide a new idea for the power enhancement of millimeter-wave and terahertz EIOs.

Research on a Highly Overmoded Slow Wave Circuit for 0.3-THz Extended Interaction Oscillator

Here, we present the complete design process of a highly overmoded slow wave circuit (SWC) stably operating in the quasi-TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{04}}$</tex-math> </inline-formula> mode for terahertz (THz) extended interaction oscillator (EIO). The developed interaction circuit emits THz frequency electromagnetic radiation through structural size of the engineered millimeter-wave (MMW) circuits, which provides a new technological horizon for overcoming the engineering challenges caused by the limitation of circuit size. Through careful engineering of the electron optical system, a cylindrical beam with a diameter of 0.38 mm and a current of 0.25 A is obtained at a bias of 14.8 kV. Through the particle-in-cell (PIC) simulation, these new design approaches have been shown to achieve an output power of 250 W at 0.3 THz in a cylindrical cavity with an inner diameter of 4.16 mm.

Novel 0.22-THz Extended Interaction Oscillator Based on the Four-Sheet-Beam Orthogonal Interconnection Structure

Numerous terahertz vacuum electronic devices (TVEDs) have been proposed. Among these devices, extended interaction oscillators (EIOs) exhibit small-volume, lightweight, low-working-voltage, stable-working frequency, and high-power characteristics. The ladder-line slow wave structure exhibits strong coupling and can interact with the sheet beam to considerably improve the efficiency of beam–wave interaction. In this study, a novel high-frequency structure was proposed. Four conventional ladder-line slow wave structures were placed vertically to form a four-sheet-beam orthogonal interconnection structure (OIS) that considerably increased the coupling efficiency between the cavities, improved output power and efficiency, and interacted perfectly with the TM81 mode. In this study, the dispersion characteristics and field distribution were studied through numerical and simulation calculations, and the optimal working parameters and output structure were analyzed using particle-in-cell (PIC) software. Next, a 0.22-THz extended interaction oscillator based on four-sheet-beam OSI was designed. Simulation results have shown the achievement of the output power of 0.22-THz wave over 500 W with four sheet beams at 16.6 kV and each current of 0.8 A. Finally, preliminary processing and cold tests of the structure were performed. This novel structure provided an alternative for the development of terahertz EIOs.

Design and Non-Uniform Current Analysis of a 0.35-THz Extended Interaction Oscillator Based on Pseudospark-Sourced Multiple Sheet Electron Beams

A novel method, which combines a multiple-beam extended interaction oscillator (EIO) with pseudospark-sourced (PS) sheet electron beams, is applied to generate high-power terahertz sources. For a multiple-beam EIO, the beam cross-section is significantly improved by replacing the commonly used pencil electron beams with sheet electron beams. The PS electron beams have the advantage of high current density and operate without a focus magnetic field. The volume of the cavity is larger when the EIO operates in the TM31-3π mode than in the conventional TM01-2π mode at the same operating frequency. The EIO operating at the terahertz frequency has a larger cavity volume, which means greater power capacity and lower manufacturing difficulty. For a PS multiple-beam EIO, the non-uniformity of electron beam currents is a common problem. In order to study this problem, an original high-order mode EIO driven by PS multiple sheet electron beams is presented with enhanced output power at 0.35 THz. The authors analyze electron beams with different currents through particle-in-cell (PIC) simulations. Simulation results show that the EIO can operate stably even in the case of non-uniform PS electron beam currents. When each current is 1.4 A, simulation results show the EIO’s output power of 4.9 kW at 0.35 THz. Considering the low conductivity of 1.1 × 107 S/m, the efficiency is still 1.42%.

Design and Cold Test on the Slow Wave Structure of a Wide-Voltage Tuned and High-Power Extended Interaction Oscillator in W-Band

In order to obtain continuously tunable high-power output in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$</tex-math> </inline-formula> -band, the slow wave structure (SWS) of a wide tuned and high-power extended interaction oscillator (EIO) was designed and studied in this article. The structure of the designed circuit was described while the operating characteristics were analyzed. The SWS not only has high power output capability but also operates near standing waves with a wide electronic tuning range. The EIO can operate over an electronic tuning range of 1.36 GHz in ensuring the output power no less than 1.6 kW, where the maximum output power over 4.5 kW is obtained at 43.8 kV and 2 A from the simulation. The wide tuning range and the high output power are achieved by increasing the number of periods with offsetting the coupling hole and beam voltage and current in order to match with high impedance modes near to 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $</tex-math> </inline-formula> . The SWS was processed and cold tested, and its S-parameter distribution was close to the simulation result. The designed 94-GHz extended interaction oscillation can be effectively used to generate wide tuned and high-power microwave radiation sources in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$</tex-math> </inline-formula> -band.

Performance and Experimental Progress of a Compact W-band High Average Power Sheet Beam Extended Interaction Oscillator

In response to the urgent requirement for a high-power millimeter-wave system with small size, low cost, and excellent maneuverability in W-band, a compact high average power sheet beam extended interaction oscillator (SB-EIO) based on periodic cusp magnet (PCM) is designed, fabricated, hot tested and reliability verified. The maximum output power is 10.2 kW at a working duty of 1%. When the duty is increased to 27%, an average power of 2.2 kW is achieved, corresponding to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$400 \mu \text{s}$ </tex-math></inline-formula> pulse and 675 Hz repetition frequency. The device can be repeatedly turned on and off quickly during a 6-minute operating time and the single longest running time exceeds 60 min. The 96.0% transmission rate of the sheet beam (45.5 kV, 2.49 A) is verified. The overall weight of SB-EIO including the magnet and external package is less than 10 kg, which is ideal for equipping movable platforms.

Simulation and experimental study of a K-band extended interaction oscillator for microwave processing systems.

High-power microwave sources have been widely applied for material processing in scientific research and manufacturing. The development of stable, high-frequency, high-power microwave sources is essential for achieving efficient microwave processing. This study proposes using a square doubly reentrant coupled-cavity as the slow-wave resonant structure in a K-band extended interaction oscillator (EIO). This design allows for ease of fabrication and high-power capability. The EIO is designed to operate in single 0-mode. The simulation results show that the competing π/5-mode can be effectively suppressed by properly choosing the width and location of the output coupler. The simulation and experiments successfully demonstrate stable, single-mode, tunable, high-performance operation of the EIO. The experimental measurements show a maximum output power of 1.776 kW (18.56% electronic efficiency), and a wave frequency of 24.324GHz at a beam voltage of 17.4kV and beam current of 550 mA. The EIO microwave source is suitable for interdisciplinary applications that require higher heating rates and greater uniformity.

Preliminary Study of a G-Band Extended Interaction Oscillator Operating in the TM31-3π Mode Driven by Pseudospark-Sourced Multiple Electron Beams

This paper presents the first design that combines pseudospark-sourced (PS) electron beams with a multiple-beam extended interaction oscillator (EIO). The PS electron beam is an excellent choice for driving EIOs because it has high current density and does not require a focusing magnetic field. The EIO with coaxial structure adopts the method of multiple electron beams, which plays a crucial role in improving the average output power. At the same frequency, the EIO operating in the high-order TM31-3π mode has a larger cavity size than the EIO operating in the traditional TM01-2π mode. The high-order TM31-3π mode solves the problem of the EIO’s manufacture at high frequency. In order to verify the above points, a G-band PS multiple-beam EIO operating in TM31-3π mode has been designed. The beam–wave interaction particle-in-cell simulation results show that the EIO’s peak output power is 39.2 kW at 217 GHz, and that its efficiency is around 6.1%. The EIO with six pencil beams operates at a voltage of 43 kV. The total current of the six electron beams is 15 A (equally distributed among the six beams), and the corresponding current density is about 5000 A/cm2. Considering the ohmic loss and the effect of skin depth, the conductivity used in these simulations is 2 × 107 S/m. The design is an excellent way to improve the output power of EIO operating at high frequency.

Research and Experiment of a W-Band High-Power Extended Interaction Oscillator With High Voltage

In order to obtain a high-power radiation source in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W</i> -band, a 95-GHz extended interaction oscillator (EIO) with high voltage was designed and tested in this article. The overall structure of the designed EIO is introduced, and the simulation results of the slow wave structure are shown. Experimental test results show that, at a high duty cycle of 50%, the 95.1-GHz radiation peak power of 3.5 kW is achieved when an electron beam with 2 A and 42.8 kV is injected. The experimental test of the designed EIO has guiding significance for miniaturized vacuum devices to obtain high-power radiation source.

Design and Experimental of a Terahertz Multi-Gap Extended Interaction Oscillator Operating in High-Order Mode

Design and Experimental of a Terahertz Multi-Gap Extended Interaction Oscillator Operating in High-Order Mode

Research on coupled cavity mechanical tuning extended interaction oscillator with broad tuning range.

This paper proposes a new way to improve the tuning range of the extended interaction oscillator (EIO). Compared with the conventional EIO structure, the fundamental wave changes from the forward wave to the backward wave when the circuit structure changes from the strong-coupling characteristic of the grating to the weak-coupling characteristic. Simultaneously, the tuning range of the EIO can be greatly enhanced by mechanically tuning the coupling cavity. The results show that, compared with the strong-coupling structure of the grating, the extended interaction oscillation circuit has stronger dispersion sensitivity and greater frequency tuning characteristics under the weak-coupling characteristics of the grating. By mechanically tuning the width of the coupling cavity by 0.8mm, its center frequency can be varied by 9.5GHz. This paper also studies and compares the electronic displacement jump phenomenon that occurs in the mechanical tuning process. Similar to the electronic voltage tuning, the output dips suddenly at the operating point of the coupling mismatch. The effective output can be obtained by changing the operating mode in conjunction with electronic tuning. This article provides a new reference method for expanding the tuning range of the extended interaction oscillator.

A Multimode Extended Interaction Oscillator With Broad Continuous Electric Tuning Range

A novel extended interaction oscillator (EIO) capable of continuous multimode operation is proposed to make the leap from the single-mode operation and continuous dual-mode operation to the continuous multimode operation and overcome the continuous electric tuning range limitation of the conventional EIO. The “cold cavity” simulation and theory demonstrate the possibility of a stable continuous multimode operation. A −3 dB continuous electric tuning range of 4.15 GHz (4.3% relative bandwidth) with a center frequency of 95.74 GHz is predicted by the “hot cavity” simulation. Meanwhile, a comparative study on the uniform-gap and stagger-gap circuit explains the working mechanism of the conventional stagger-gap circuit with a single-mode ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> mode) operation.

Design and research of a novel structure for extended interaction oscillators

To improve the bandwidth and output of an extended interaction oscillator (EIO), this article proposes a new structure and tests its S parameters. Through simulation analysis and theoretical calculations, it is verified that the structure cannot only increase the bandwidth of the device but also suppress the influence of weak-coupling characteristics of the grating and increases the power capacity of the device. The optimized structure was analyzed by particle-in-cell simulations. The results show that the X-EIO structure has a wide electrical tuning range of 800 MHz under the condition that the effective output is not less than 150 W. The dual-coupling hole of this structure cannot only obtain the same frequency and the same power output synchronously but also has higher efficiency and greater power than the traditional single-hole output. With oxygen-free copper as the background material, at 20.8 kV, 1 A electron beam injection, both coupling holes can obtain a power of more than 2.6 kW, and the highest output efficiency reaches 12.67%. The slow-wave structure has been assembled and tested, and the distribution result of its S parameter is similar to the simulation result, which can achieve broadband adjustable output.