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Theoretical study of electromagnetic wave pumped ion-channel free-electron laser (EPIC-FEL) is presented. The physical mechanism responsible for the generation of coherent radiation in the EPIC-FEL is described and the fundamental role of the ponderomotive wave in bunching and trapping the beam is emphasized. The dispersion relation of the EPIC-FEL has been obtained and growth rates are calculated for different parameters. It shows that EPIC-FEL has a very bright future.

A new hybrid maser instability is described for the case of wave interactions for an electron-beam (e-beam) propagating through an ion channel in a plasma-filled waveguide immersed in a finite axial magnetic field. Complete linear theoretical formulation and sample numerical calculations are presented. The significant features of this new hybrid instability are discussed.

This two-part paper presents the first complete, generalized basic theoretical formulation for electron beam-wave interactions in a plasma-filled (corrugated or smooth-walled) waveguide immersed in a finite magnetic field. The general interaction and dispersion equations of the longitudinal and transverse interactions in both smooth and corrugated magnetized plasma-filled waveguides (MPWs) are formulated. Our approach differs from that of previous investigators in that we begin by first deriving the dispersion relation of an MPW and then using the resulting electromagnetic fields, which embody the plasma effects, as the basis field vectors. We then investigate the underlying interactions with a superimposed electron-beam in a variety of microwave device configurations. For example, we examine plasma Cherenkov radiation, the plasma-filled travelling-wave-tube/backward-wave-oscillator (TWT/BWO), the plasma-filled electron cyclotron resonance maser (ECRM), and other beam-wave interactions including those involving ion-channels. Some possible new interactions in a magnetized plasma-filled waveguide (MPW) are proposed. A detailed discussion and analysis of the important physical role of the plasma background are given. Many interesting features of beam-wave interactions in an MPW are pointed out, three of them being most essential. One is that transverse interactions are always accompanied by longitudinal interactions. The second is that the magnetized plasma itself is strongly involved in the interaction mechanisms via an additional component of the field. The third interesting feature is that the plasma-filled ECRM prefers to operate at high cyclotron harmonics. The first part of this two-part paper presents formulations using a fluid model for both the plasma and the beam. It also includes a detailed treatment of the physical effects of the ion channel that is formed in the plasma by an intense electron beam. Part II extends the analyzes by retaining a fluid treatment for the plasma-fill but substituting a kinetic theory treatment for the electron beam. This kinetic theory model should be used when the velocity spread of the beam's electrons must be taken into account. The theory presented in both parts of this paper is based upon the "given field" approach that has been widely used successfully in science and technology, in particular in microwave electronics. In both parts of the paper, sample numerical calculations are also presented in order to illustrate the physics.

For pt.I see ibid., vol.28, no.6, p.2135-51 (2000) Building upon the theoretical foundations presented in Part I of this paper, the kinetic theory of electron-beam-wave interactions in a magnetized plasma-filled waveguide (MPW) is presented in this second part. This kinetic theory treatment is more generally applicable to cases of less-intense electron-beams (Montgomery and Tidman, 1964). The dispersion relations for longitudinal and transverse interactions, in both smooth and corrugated waveguides, are all derived by using kinetic theory to model the e-beam dynamics. This includes kinetic theory treatments of the plasma filled electron cyclotron resonance maser (ECRM) and a combination of Cherenkov-cyclotron resonance phenomena. It is important to note that in an MPW, transverse interactions (e.g., ECRM interactions) are always coupled with longitudinal interactions. Using the kinetic treatment is essential for studying the ECRM because its energy conversion mechanism is based on azimuthal phase bunching and finite Larmor radius effects. The dispersion relation that we derive shows that the presence of a plasma-fill tends to increase the growth rate of the waveguide mode ECRM instability.

From the fluid model, the plasma is an isotropic medium. First, it is obtained that the microwave field in a cylindrical cavity filled with plasma, where the microwave comes from vacuum cylindrical waveguide. Coupling with fluid equations for the electron and ion motion, the microwave discharge courses are calculated. The results show that the curves of ion and electron density distributions are similar as the curves of electric field intensity distribution. Also, a critical electron density is exist. Above this density, microwave field will damp rapidly, this makes the gas ionization mainly happening on the surface.

Starting from general transmission line equations with an electron beam source, a self-consistent nonlinear theoretical model for a complex cavity gyrotron with gradual transitions is presented in this paper. The model accounts for mode coupling in the transition region of the complex cavity. The interaction between the electron beam and H/sub 61/-H/sub 62/ RF field in the complex cavity for a third-harmonic gyrotron is simulated; many calculations are carried out under different cavity dimensions and electron beam parameters.

In a relativistic electron cyclotron maser with an axisymmetrical quasioptical cavity of oblique rotation at arbitrary angle, the rotating angle has a great influence on beam-wave interaction. Two different physical mechanisms are found with the rotating angle ranging from 0° to 90°. One is cyclotron auto-resonance maser regime for small angle, with small optimized external magnetic field; the other is electron cyclotron resonance maser regime for large angle, with comparatively large optimized magnetic field.

The angular spectrum of spontaneous emission in a two-dimensional undulator free-electron laser is analyzed theoretically. Numerical calculation shows that thes-th harmonic spontaneous emission power density can be greatly enhanced by using a two-dimensional undulator, for whichl=s, so the harmonic number can be selected by selectingl. Therefore, the higher harmonic operation of a free-electron laser can be realized selectively.

We observed a photon-phonon resonance or polariton arises in PbB 4 O 7 crystal. We identified this resonance state is a phonon, ν TO =1.56THz and q=1930cm−1, because the transmissivity T(ν p ) is almost zero, the dielectric function e(ν) satisfies the Lyddane-Sachs-Teller (LST) relation, and a split appears at 1.56THz in ν(k) curve.

Here the cyclotron electron beam (CEB) excitation of surface plasmon polaritons (SPPs) on the circular cylindrical structures is used to replace the linearly moving electron beam excitations. We have found that this change leads to essential consequence in physics for that there is natural periodicity of 2π in both circular cylindrical structure and CEB, and the combination of this dual natural periodicity not only make the excited SPPs transformation possible, but also bring many significant excellences to the mechanism.

In relativistic plasma electronics, both theoretical and experimental studies indicate that the operating frequency of the mechanism of electron beam coupled with a TG mode wave in plasma filled waveguide can not be higher than either the plasma frequency or the beam plasma frequency. However, our recent investigation on the two stream instability (TSI) shows that the operating frequency may be much higher than plasma frequency or the beam plasma frequency.

To meet the needs of the ITER program, the coaxial cavity gyrotron with very high mode, like TE/sub 43.19/, operating at 170GHz with 2MW CW output power was proposed and studied. Since there are outer and inner conducting cylinders with the same electric potential, and the high mode makes the size of the cavity large enough. The high mode coaxial cavity structure, therefore, enables the suggestion of the two-electron beam coaxial gyrotron (TBCG). This paper deals with the coaxial gyrotron with two-electron beam, and the computer calculations have been carried out. The detailed comparison of the performances of the two-beam gyrotron with that of one-beam is given as well in the paper. The study on the two beam coaxial gyrotron shows that the two beam gyrotron may performance quite well, for example, the TBCG may enhance the higher output power for the two beams may provide higher electric current; and it may improve the mode competition for working at very high mode with potential V=90kV. Detailed analysis and computer simulations for all mention are given in the paper.

Wave propagation along a plasma waveguide is one of the most interesting and attractive topics in plasma physics and microwave plasma electronics. In the authors' previous paper (Liu Shenggang et al, Physical Rev. E, vol. 65, no. 3, pp. 036411-1-036411-8, 2002), a lot of interesting and important features in physics were revealed for wave propagation along waveguides filled with moving magnetized plasma (MMPW). A theoretical study on the non-reciprocal properties and the extreme relativistic cases are given in this paper. The numerical calculations show that in a MMPW there exists a non-reciprocal property, and it strongly depends upon the drift velocity of the plasma. As a consequence, the wave propagation in the opposite direction is quite different from that in the positive direction.

Gives accurate dispersion equations and shows that dispersion characters of wave propagation in partially plasma filled waveguide are quite different with that in completely plasma filled waveguide, and the dispersion curves of all waves can not pass across the critical frequency line: /spl omega/=/spl omega//sub h/=(/spl omega//sup 2//sub ce/+/spl omega//sub pe//sup 2/)/sup 1/2 /. It has been found that some calculations given in published papers should be checked and corrected. It shows that the p/sub 2/=0 curve in the p/sub 1//sup 2/, p/sub 2//sup 2/ diagram, for example, has only one line rather than two lines and there is no so called anisotropic waves dispersion curve HE/sub 1/. A new kind of wave which is unknown in published papers has been found, the unusual dispersion characteristics of this kind of wave are discussed. Hence there are two kinds of waves, electromagnetic waves and waves containing quasi-static parts.

Experimental studies of a gas-filled free-electron laser pumped by a relativistic backward-wave oscillator without magnetic field were performed. Radiation power from FEL and BWO both were observed for argon pressure between 2.3 mTorr to 15 mTorr, with maximum power at 5.3 mTorr. Theoretical studies of the radiation mechanism are underway.

Self_modulation may appear on an intense relativistic electron beam(IREB) trave rsing a two_cavity klystron system. It is caused by the intense relativistic eff ect. RF output can be obtained without RF input. Based on this mechanism, a new type of high_power microwave source is suggested. The oscillation condition of t he intense relativistic election beam, traverse mechanism and PIC simulation are presented. After optimization design, a 800MW output peak microwave power was o bserved at a frequency of 099GHz, while an electron beam of voltage 500kV, cur rent 4kA is injected. The efficiency is about 40%.

A corrugated waveguide filled with an infinitely thin annular plasma is immersed in a strong longitudinal magnetic field. By means of fluid model and linear field theory，the dispersion relation of the electromagnetic wave propagation along the system is derived. The dispersion characteristics and beamwave interactions of lowfrequency plasma modes are analyzed in two cases of various densities of plasma by numerical computation. It is found that the dispersion relation with out electron beam satisfies exactly the Floquet theorem and the frequency of electromagnetic wave could not be confined by plasma oscillation frequency. The low-frequency plasma modes can even be coupled with TM modes as the plasma density i s increased.

A new type of slow-wave system (SWS) for the beam-wave interaction——putting a plasma column into a dielectric-partially-filled waveguide, is presented. By use of the linear self-consistent field theory, the interaction of a relativistic electron beam with the wave in the SWS is analysed. Determinative dispersion equations are derived for a thin annular relativistic electron beam propagating through the SWS surrounding and existing inside the plasma column, respectively. These dispersion equations are directly solved numerically, and the cut-off frequency, the operation frequency and the growth rate of the waves are obtained. Finally, the effects of the parameters of the plasma column on them are discussed.

A new plasma maser scheme,the ion-channel electron cyclotron maser (ICECM) is proposed.By making use of the three-dimensional fluid theory,the dispersion relation of the ICECM with circular orbit electron beam is derived.An ion electrostatic gyro-penitron mode is found,and the growth rate of this new mode is obtained by numerical calculation.

By use of the self-consistent linear field theory, three-dimensional perturbation of electrons affected by the perturbed electromagnetic fields is discussed. And Cherenkov radiations excited by a thin annular relativistic electron beam in a unmagnetized-plasma-filled, dielectric lined slow-wave waveguide are analysed. The dispersion equation and the wave growth rate of the interaction of the electron beam to the waveguide modes with arbitrary azimuthal mode number are derived. It′s clearly shown that the Cherenkov radiation results from the coupling of the waveguide mode in the unmagnetized-plasma-filled, dielectric lined slow-wave waveguide to the beam mode via the electron beam. Finally, the effects of plasma density on the dispersion relation and the wave growth rate are calculated and discussed.

Influence of untrapped electrons on the sideband instability of electromagnetic Wiggler free electron laser (EM一FEL) is analyzed in detail with single-particle theory. The dispersion equation is derrived by applying the methode in Ref.[1]，and detailed discussions are carried out, some conclusions are drawn.

The problems concerning the specification of electron equilibrium distribution function for the kinetic theory of ECRM are investigated in this paper. After detailed analysis of the published equilibium distribution functions, several conclusion have been achieved.

A new scheme of the electrostatic electron cyclotron resonance maser with slotted coaxial waveguide is presented here. Having studied it both in the linear and non linear regimes, we found that the radiation frequency and the converting efficiency could be increased largely for the low-energy electron beam in this scheme. The maximum converting efficiency of electrons with the π azimuthal mode can reach 23%. It has been revealed that there exist azimuthal and radical electron benching phenomena, corresponding to the kinetic and potential energy converting processes of electrons with the RF field. This revelation is helpful when looking into the physics of the electrostatic electron cyclotron resonance masers and other kinds of microwave devices with an electrostatic centrifugal field

The paper, by means of Green's function and Fourier spectral theory, investigates spontaneous radiation of a single pulse electron bean in free electron lasers with a helically periodical magnetic field. It is found that there are fast and slow electroagnetic waves as well as normal in the interaction region, and that the energy spectrum of spontaneous emission is not only dependent on the imposed helical field, but also modulated sensitively by the electron beam pulse. Under some conditions, the spectrum may have main peaks more than one, showing oscillations, that is, the long pulse effect.

The kinetic theory of the electron cyclotron resonance maser is given in this paper with the space charge effect and non-resonance cyclotron harmonics taken into consideration. The dispersion equations have been calculated using a digital computer and the influence of these factors are discussed in detail.

A set of coupled equations for electron motion and the dispersion relation of electromagnetic wave (wiggler) in electron beam are studied. The instability of steady-state electron orbits is reduced to the problem of the fourth-order and fifth-order linear ordinary differential equations. It is found that the presence of self-fields plays an important role in determining the behaviour of stable electron orbits.

The spontaneous radiation from a single pulse electron beam in Free Electron Lasers is dealt with by solving one-dimensional wave equations. The obtained results show that there is the long pulse effect as well as the well-known short pulse effect.

Starting from basic concepts, we propose a new kind of free-electron laser(FEL) : the pump-free crossed-field FEL in which the condition E 0 + V 0 xB 0 =0 is not satisfied, and the electron orbit without radiation fields and undulator or wiggler fields is not straight line (in planar configuration). In the fluid dynamical analysis without taking account of the space charge effect, FEL instability is found near resonance Ω ±1– kz a =0, while no FEL instability near resonance Ω q -kz a +± √1-β2 za Ω 0 =0.

The free‐electron laser (FEL)–electrostatic electron cyclotron resonance maser (EECRM) hybrids, a new kind of FEL comprised of a relativistic electron beam and an electrostatic centrifugal field, are presented and studied in this paper. In a fluid dynamical linear theory, the dispersion equation for transverse electromagnetic (TEM) mode operation is derived, analyzed, and numerically solved. It is found both analytically and numerically that FEL instability occurs near beam resonance [(ωl−klv∥)2−ω2p (γ−2∥ −β2∥β2⊥φ20/ Ω2l)=0]. However, FEL instability near cyclotron resonance (ωs−ksv∥ =±(2−β2⊥)1/2φ0) is not found in the TEM mode analysis.