The higher harmonics of the free electron laser(FEL)with a two-wavenumber plane wiggler magnetic field,which may induce a lot of higher harmonics,are investigated.Using a two-wavenumber wiggler comprised of two separa...The higher harmonics of the free electron laser(FEL)with a two-wavenumber plane wiggler magnetic field,which may induce a lot of higher harmonics,are investigated.Using a two-wavenumber wiggler comprised of two separate periodicities,k_(ω)and k_(ω)+Δk,numerical simulations show that the higher harmonic may be amplified and the first harmonic may be suppressed in this kind of FEL with an optimized parameterΔk.The coupling coefficient and gain coefficient in low-gain regime of the harmonic are also obtained.展开更多
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 mec...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.展开更多
Using kinetic coupling mode theory of three waves,the effect of longitudinal momentum spread in ion-ripple laser(IRL),which is an advanced new scheme to generate tunable-coherent radiation with frequency ranging from ...Using kinetic coupling mode theory of three waves,the effect of longitudinal momentum spread in ion-ripple laser(IRL),which is an advanced new scheme to generate tunable-coherent radiation with frequency ranging from microwaves to x-rays,is investigated.For a Gaussian distribution in beam longitudinal momentum,the results show that the growth rate of IRL falls off rapidly with increasing momentum spread,and the momentum spread causes linear damping of beam space-charge wave,weakening the beam-radiation mode coupling and lowering the output radiation frequency apart from broadening the radiation spectrum.The dispersion relation and phase matching conditions are also obtained.展开更多
Following a single-particle approach,a detailed analysis of the higher harmonic in free electron laser(FEL)with combined electromagnetic wiggler and axial guide magnetic fields is derived.The spontaneous emission spec...Following a single-particle approach,a detailed analysis of the higher harmonic in free electron laser(FEL)with combined electromagnetic wiggler and axial guide magnetic fields is derived.The spontaneous emission spectrum and the gain in the low-gain Compton regime are also calculated in detail.This analysis results in a clear resonance condition and shows that this kind of FEL can generate significant coherent harmonic emission of radiation with axial guide magnetic field of suitable strength.展开更多
The small-signal linear gain for a combined electromagnetic wiggler and an axial-guide magnetic field free electron laser is derived within the presence of beam equilibrium self-fields.The numerical results show that ...The small-signal linear gain for a combined electromagnetic wiggler and an axial-guide magnetic field free electron laser is derived within the presence of beam equilibrium self-fields.The numerical results show that the gain is reduced as the self-fields increase.展开更多
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 ...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.展开更多
文摘The higher harmonics of the free electron laser(FEL)with a two-wavenumber plane wiggler magnetic field,which may induce a lot of higher harmonics,are investigated.Using a two-wavenumber wiggler comprised of two separate periodicities,k_(ω)and k_(ω)+Δk,numerical simulations show that the higher harmonic may be amplified and the first harmonic may be suppressed in this kind of FEL with an optimized parameterΔk.The coupling coefficient and gain coefficient in low-gain regime of the harmonic are also obtained.
基金Supported by the Doctoral Fund of the State Education Committee of China.
文摘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.
文摘Using kinetic coupling mode theory of three waves,the effect of longitudinal momentum spread in ion-ripple laser(IRL),which is an advanced new scheme to generate tunable-coherent radiation with frequency ranging from microwaves to x-rays,is investigated.For a Gaussian distribution in beam longitudinal momentum,the results show that the growth rate of IRL falls off rapidly with increasing momentum spread,and the momentum spread causes linear damping of beam space-charge wave,weakening the beam-radiation mode coupling and lowering the output radiation frequency apart from broadening the radiation spectrum.The dispersion relation and phase matching conditions are also obtained.
文摘Following a single-particle approach,a detailed analysis of the higher harmonic in free electron laser(FEL)with combined electromagnetic wiggler and axial guide magnetic fields is derived.The spontaneous emission spectrum and the gain in the low-gain Compton regime are also calculated in detail.This analysis results in a clear resonance condition and shows that this kind of FEL can generate significant coherent harmonic emission of radiation with axial guide magnetic field of suitable strength.
文摘The small-signal linear gain for a combined electromagnetic wiggler and an axial-guide magnetic field free electron laser is derived within the presence of beam equilibrium self-fields.The numerical results show that the gain is reduced as the self-fields increase.
文摘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.
