An overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic (TEM) mode output is designed and presented, by using a kind of coaxial slow wave structure (SWS) with large transversal dimension and small distance between inner and outer conductors. The generator works in dual-mode operation mechanism. The electron beam synchronously interacts with 7π/8 mode of quasi-TEM, at the meanwhile exchanges energy with 3π/8 mode of TM01. The existence of TM01 mode, which is traveling wave, not only increases the beam-wave interaction efficiency but also improves the extraction efficiency. The large transversal dimension of coaxial SWS makes its power capacity higher than that of other reported millimeter-wave devices and the small distance between inner and outer conductors allows only two azimuthally symmetric modes to coexist. The converter after the SWS guarantees the mode purity of output power. Particle-in-cell simulation shows that when the diode voltage is 400 kV and beam current is 3.8 kA, the generation of microwave at 32.26 GHz with an output power of 611 MW and a conversion efficiency of 40% is obtained. The power percentage carried by TEM mode reaches 99.7% in the output power.

A dual-mode operation overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic mode output

This paper presents preliminary research on a V-band overmoded Cerenkov generator with dual-cavity reflector operating in a low guiding magnetic field. It is found that the fluctuation of the electron envelope in the low guiding magnetic field can be predicted using an equivalent coaxial model of a foilless diode, and a dual-cavity reflector based on the model matching method can provide strong reflection at the front end of the overmoded structures so that any microwave power that leaks into the diode region can be effectively suppressed. Numerical simulations indicate that the control of the beam envelope and the use of the dual-cavity reflector ease generator operation in the low guiding magnetic field. In the experimental research, the fluctuation of the annular electron beam with the outer radius of 7.5 mm measures approximately 0.7 mm, which is in good agreement with the theoretical results. The disturbance caused by power leaking from the overmoded slow wave structure is eliminated by the dual-cavity reflector. With accurate fabrication and assembly processes, an operating frequency of 61.6 GHz is attained by the fifth harmonic heterodyne method, and the output power is measured to be approximately 123 MW by the far-field measurement method at a diode voltage of 445 kV, a beam current of 4.45 kA, and under a guiding magnetic field of 1.45 T. The output mode is measured using an array of neon flash bulbs, and the pulse shortening phenomenon is both observed and analyzed.

Preliminary research on overmoded high-power millimeter-wave Cerenkov generator with dual-cavity reflector in low guiding magnetic field

A Ka -band relativistic backward-wave oscillator (RBWO) operating in the TM02 mode is researched theoretically and experimentally in this article. The RBWO can overcome the disadvantages of a traditional RBWO, such as small size and low-power capability, when the operating frequency goes to the millimeter-wave band and is more suitable for adopting a lower-guiding magnetic field. The mode-selection mechanisms in the RBWO ensure that the electron beam interacts with the negative first-harmonic wave of the TM02 mode efficiently. The particle-in-cell (PIC) simulation preformed the 490-MW output power at a frequency of 29.3 GHz. The experiment was done on the SINUS-881 accelerator, and with the diode voltage and current at 580 kV and 3.6 kA, respectively, at a guiding magnetic field of 1 T, the RBWO produced a microwave pulse with a power as high as 360 MW at a central frequency of 29.3 GHz. The dependence of microwave power on diode voltage coincides with PIC simulation. Pulse shortening as well as severe bombarding damage of the electron beam on the postcascaded resonators were observed. By increasing the guiding magnetic field to 1.26 T, the pulsewidth was evidently improved.

Research on an Overmoded $Ka$ -Band RBWO Operating in TM 02 Mode With Low-Guiding Magnetic Field

The concept of two-wave relativistic Cherenkov oscillator for the generation of nanosecond microwave pulses at ∼72 GHz central frequency has been applied A moderately oversized sectioned slow wave structure (average diameter ≈25 wavelength) provides the interaction of electrons simultaneously with a slow (or surface) TM01 wave and a fast (or volume) TM02 wave, which govern the microwave energy output The generation of 85 MW, 13-ns long microwave pulses has been demonstrated in a single pulse operation with a pulsed guiding magnetic field of 38 T on the base of the desktop high-current accelerator RADAN-303

Numerical and experimental investigation of 4 mm wavelength microwave oscillator based on high-current compact accelerator

This article presents time-dependent numerical modeling of V-band relativistic orotron: a high-power microwave generator with a TM03 oscillation mode in an oversized (D/λ ∼ 27) electrodynamic structure and diffractive output in the TM02 mode Single-mode operation of the oscillator is ensured by the cyclotron selection of the working axisymmetric mode, with simultaneous depression of competing non-axisymmetric modes by means of cutting longitudinal slits in the wall of the slow-wave structure The simulated output microwave power is 350 MW with a power conversion efficiency of 31% when using a 36 kA, 310 keV electron beam transported in the 39 T magnetic field The simulation employed 25D axisymmetric and 3D Cartesian versions of the KARAT code

Efficient 58-GHz relativistic orotron with combined mode selection

A V-band overmoded relativistic backward wave oscillator (RBWO) guided by low magnetic field and operating on a TM03 mode is presented to increase both the power handling capacity and the wave-beam interaction conversion efficiency. Trapezoidal slow wave structures (SWSs) with shallow corrugations and long periods are adopted to make the group velocity of TM03 mode at the intersection point close to zero. The coupling impedance and diffraction Q-factor of the RBWO increase, while the starting current decreases owing to the reduction of the group velocity of TM03 mode. In addition, the TM03 mode dominates over the other modes in the startup of the oscillation. Via numerical simulation, the generation of the microwave pulse with an output power of 425 MW and a conversion efficiency of 32% are achieved at 60.5 GHz with an external magnetic field of 1.25 T. This RBWO can provide greater power handling capacity when operating on the TM03 mode than on the TM01 mode.

A millimeter wave relativistic backward wave oscillator operating in TM03 mode with low guiding magnetic field

How terahertz signals perform in the neural system has attracted widespread interest in the life sciences community. Relevant experimental reveals that in animal nerve cells, the myelin sheath of the nerve axon has a higher refractive index than the intracellular and extracellular fluids in the Terahertz-far-infrared (THz-FIR) frequency band. This makes THz-FIR wave transmission possible in nerve fibers. Based on this premise, this article carries out the following work from the theoretical level to investigate the electromagnetic (EM) characteristics of in vivo nerve fibers at the THz-FIR band. First, the EM transmission model of the nerve fibers is established and studied theoretically. The dispersion curves of THz-FIR wave modals transmission in nerve fibers are calculated, which predict that nerve fibers can act as dielectric waveguides for transmitting THz-FIR waves and the THz-FIR waves can transmit at speeds up to 108 m/s. Second, a mode matching algorithm is proposed, which is named RNMMA, to calculate the transmission characteristics of THz-FIR waves at the nodes of Ranvier. The scattering matrix obtained from the proposed algorithm is in good agreement with the results from EM simulation software, which reveals how THz-FIR signals are transmitted forward through the nodes of Ranvier with low loss.

/pdf/electromagnetic-characteristics-of-in-vivo-nerve-fibers-at-2wn8u2v5.pdf

Electromagnetic characteristics of in vivo nerve fibers at the terahertz-far-infrared band

Experiments show that terahertz (THz) electromagnetic waves can have a potential impact on a variety of physical and chemical properties of proteins and the synthesis of some substances in vivo. Many experiments use vacuum electronic devices to research THz biological effects. Based on molecular dynamics (MD) simulation, this paper analyzes the effect of specific frequency of THz electromagnetic wave on the binding of choline and acetyl coenzyme-A (acetyl-CoA) and then analyzes the effect of THz electromagnetic waves on the synthesis of the neurotransmitter acetylcholine (Ach). This research has guiding significance for the influence of THz electromagnetic waves on Ach synthesis and the selection of THz electromagnetic wave frequency in future experiments.

The Analysis of THz Electromagnetic Waves Effect on Acetylcholine Synthesis based on MD Simulation

Both theoretical simulations and experimental studies have tentatively shown that terahertz(THz) or mid-infrared(IR) electromagnetic waves are capable of modifying the permeability of specific ion channels. Vacuum electronics are an indispensable high-power source for conducting terahertz bioeffects experiments. However, there is currently a lack of theoretical tools to link kinetic simulations with electrophysiological experiments on relevant biological effects. Based on a modified Hodgkin-Huxley model, this paper analyzes the effect of the altered channel permeability properties on the electrical activity of neurons. Simulations showed that the alteration of ion channel permeability could directly trigger the action potential of neurons. This study bridges the interconnection between the phenomena in relevant theoretical simulations and experimental studies.

Theoretical Analysis of the Effects of THz-IR Modulation of Ion Channel Permeability on Neuronal Electrical Activity

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Hui Ning

Author Tools

Chat about Author