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采用单电子模型和经典辐射理论分别对低能和高能电子在线偏振激光驻波场中的运动和辐射过程进行了研究. 结果表明: 垂直于激光电场方向入射的低速电子在激光驻波场中随着光强的增大, 逐渐从一维近周期运动演变为二维折叠运动, 并产生强的微米量级波长的太赫兹辐射; 高能电子垂直或者平行于激光电场方向入射到激光驻波场中, 都会产生波长在几个纳米的高频辐射; 低能电子与激光驻波场作用中, 激光强度影响着电子的运动形式、辐射频率以及辐射强度; 高能电子入射时, 激光强度影响了电子高频辐射的强度, 电子初始能量影响着辐射的频率; 电子能量越高, 产生的辐射频率越大. 研究表明可以由激光加速电子的方式得到不同能量的电子束, 并利用电子束在激光驻波场的辐射使之成为太赫兹和X射线波段的小型辐射源. 研究结果可以为实验研究和利用激光驻波场中的电子辐射提供依据. 相似文献
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Chen K.-R. Katsouleas T.C. Dawson J.M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(5):837-841
The amplification mechanism of the ion-channel laser (ICL) in the low-gain regime is studied. In this concept, a relativistic electron beam is injected into a plasma whose density is comparable to or lower than the beam's density. The head of the electron beam pushes out the plasma electrons, leaving an ion channel. The ion-focusing force causes the electrons to oscillate (betatron oscillations) about the axis and plays a role similar to the magnetic field in a cyclotron autoresonance maser (CARM). Radiation can be produced with wave frequencies from microwaves to X-rays depending on the beam energy and plasma density: ω~2γ3/2ωpe, where γ is the Lorentz factor of the beam and ωpe is the plasma frequency. Transverse (relativistic) bunching and axial (conventional) bunching are the amplification mechanisms in ICLs; only the latter effect operates in free-electron lasers. The competition of these two bunching mechanisms depends on beam velocity ν0z; their dependences on ν0z cancel for the cyclotron autoresonance masers. A linear theory is developed to study the physical mechanisms, and a PIC (particle-in-cell) simulation code is used to verify the theory. The mechanism is examined as a possible explanation for experimentally observed millimeter radiation from relativistic electron beams interacting with plasmas 相似文献
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For the interpretation of experiments for acceleration of electrons at interaction up to nearly GeV energy in laser produced
plasmas, we present a new model using interaction magnetic fields. In addition to the ponderomotive acceleration of highly
relativistic electrons at the interaction of very short and very intense laser pulses, a further acceleration is derived from
the interaction of these electron beams with the spontaneous magnetic fields of about 100 MG. This additional acceleration
is the result of a laser-magnetic resonance acceleration (LMRA) around the peak of the azimuthal magnetic field. This causes
the electrons to gain energy within a laser period. Using a Gaussian laser pulse, the LMRA acceleration of the electrons depends
on the laser polarization. Since this is in the resonance regime, the strong magnetic fields affect the electron acceleration
considerably. The mechanism results in good collimated high energetic electrons propagating along the center axis of the laser
beam as has been observed by experiments and is reproduced by our numerical simulations.
PACS 41.75.Jv; 52.38.Kd; 52.65.Cc 相似文献
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In this paper the electron axial channeling radiation has been compared with a free electron laser (FEL),and the possibility of reforming this type of radiation as γ–laser has been discussed.introducing equivalent magnetic field to describe ~electron’s motion,the pendulum equation and energy gain of the electron longitudial motion have been obtained using interaction of the electron with the radiation field. it shows that the channeling radiation is very similar to fel, if there exists standing wave field in the crystal. 相似文献
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Arbel M Abramovich A Eichenbaum AL Gover A Kleinman H Pinhasi Y Yakover IM 《Physical review letters》2001,86(12):2561-2564
An electron beam, prebunched at the synchronous free-electron laser frequency and passing through a magnetic undulator, emits coherent (superradiant) synchrotron undulator radiation at the bunching frequency. If an external electromagnetic wave is introduced into the interaction region, at the same frequency and at a proper phase, the radiation process will be stimulated (stimulated prebunched beam radiation). We report first experimental measurements of stimulated superradiant emission in a prebunched free-electron maser. Measurements are in good agreement with theory. 相似文献
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Quantum regime of a plasma‐wave‐pumped free‐electron laser in the presence of an axial magnetic field 下载免费PDF全文
The quantum regime of a plasma‐whistler‐wave‐pumped free‐electron laser (FEL) in the presence of an axial‐guide magnetic field is presented. By quantizing both the plasma whistler field and axial magnetic field, an N‐particle three‐dimensional Hamiltonian of quantum‐FEL (QFEL) has been derived. Employing Heisenberg evolution equations and introducing a new collective operator which controls the vertical motion of electrons, a quantum dispersion relation of the plasma whistler wiggler has been obtained analytically. Numerical results indicate that, by increasing the intrinsic quantum momentum spread and/or increasing the axial magnetic field strength, the bunching and the radiation fields grow exponentially. In addition, a spiking behavior of the spectrum was observed with increasing cyclotron frequency which provides an enormous improvement in the coherence of QFEL radiation even in a limit close‐to‐classical regime, where an overlapping of these spikes is observed. Also, an upper limit of the intrinsic quantum momentum spread which depends on the value of the cyclotron frequency was found. 相似文献
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Axial magnetic field effect in numerical analysis of high power Cherenkov free electron laser 下载免费PDF全文
《中国物理 B》2019,(6)
Cherenkov free electron laser(CFEL) is simulated numerically by using the single particle method to optimize the electron beam. The electron beam is assumed to be moving near the surface of a flat dielectric slab along a growing radiation. The set of coupled nonlinear differential equations of motion is solved to study the electron dynamics. For three sets of parameters, in high power CFEL, it is found that an axial magnetic field is always necessary to keep the electron beam in the interaction region and its optimal strength is reported for each case. At the injection point, the electron beam's distance above the dielectric surface is kept at a minimum value so that the electrons neither hit the dielectric nor move away from it to the weaker radiation fields and out of the interaction region. The optimal electron beam radius and current are thereby calculated. This analysis is in agreement with two previous numerical studies for a cylindrical waveguide but is at odds with analytical treatments of a flat dielectric that does not use an axial magnetic field. This is backed by an interesting physical reasoning. 相似文献
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Babzien M Ben-Zvi I Kusche K Pavlishin IV Pogorelsky IV Siddons DP Yakimenko V Cline D Zhou F Hirose T Kamiya Y Kumita T Omori T Urakawa J Yokoya K 《Physical review letters》2006,96(5):054802
A free relativistic electron in an electromagnetic field is a pure case of a light-matter interaction. In the laboratory environment, this interaction can be realized by colliding laser pulses with electron beams produced from particle accelerators. The process of single photon absorption and reemission by the electron, so-called linear Thomson scattering, results in radiation that is Doppler shifted into the x-ray and gamma-ray regions. At elevated laser intensity, nonlinear effects should come into play when the transverse motion of the electrons induced by the laser beam is relativistic. In the present experiment, we achieved this condition and characterized the second harmonic of Thomson x-ray scattering using the counterpropagation of a 60 MeV electron beam and a subterawatt CO2 laser beam. 相似文献
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Electron acceleration in the inverse free electron laser (IFEL) with a helical wiggler in the presence of ion-channel guiding and axial magnetic field is investigated in this article. The effects of tapering wiggler amplitude and axial magnetic field are calculated for the electron acceleration. In free electron lasers, electron beams lose energy through radiation while in IFEL electron beams gain energy from the laser. The equation of electron motion and the equation of energy exchange between a single electron and electromagnetic waves are derived and then solved numerically using the fourth order Runge-Kutta method. The tapering effects of a wiggler magnetic field on electron acceleration are investigated and the results show that the electron acceleration increases in the case of a tapered wiggler magnetic field with a proper taper constant. 相似文献
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In this paper, the trajectory and kinetic energy of a charged particle, subjected to interaction from a laser beam containing
an additionally applied external static axial magnetic field, have been analyzed. We give the rigorous analytical solutions
of the dynamic equations. The obtained analytical solutions have been verified by performing calculations using the derived
solutions and the well known Runge-Kutta procedure for solving original dynamic equations. Both methods gave the same results.
The simulation results have been obtained and presented in graphical form using the derived solutions. Apart from the laser
beam, we show the results for a maser beam. The obtained analytical solutions enabled us to perform a quantitative illustration,
in a graphical form of the impact of many parameters on the shape, dimensions and the motion direction along a trajectory.
The kinetic energy of electrons has also been studied and the energy oscillations in time with a period equal to the one of
a particle rotation have been found. We show the appearance of, so-called, stationary trajectories (hypocycloid or epicycloid)
which are the projections of the real trajectory onto the (x, y) plane. Increase in laser or maser beam intensity results
in the increase in particle’s trajectory dimension which was found to be proportional to the amplitude of the electric field
of the electromagnetic wave. However, external magnetic field increases the results in shrinking of the trajectories. Performed
studies show that not only amplitude of the electric field but also the static axial magnetic field plays a crucial role in
the acceleration process of a charged particle.
At the authors of this paper best knowledge, the precise analytical solutions and theoretical analysis of the trajectories
and energy gains by the charged particles accelerated in the laser beam and magnetic field are lacking in up to date publications.
The authors have an intention to clarify partly some important aspects connected with this process. The presented theoretical
studies apply for arbitrary charged particle and the attached figures-for electrons only. 相似文献
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R. P. Fischer W. M. Manheimer A. W. Fliflet 《International Journal of Infrared and Millimeter Waves》1997,18(4):759-778
The linear theory used to design a two-resonator 85 GHz quasioptical gyroklystron with a nonuniform magnetic field is presented.
It is shown that a tapered magnetic field in the prebunching resonator has a relatively small effect on the electron bunching
parameter. The effect of velocity spread of the electron beam can be minimized by adjusting the magnetic field strength in
the two resonators. Measured amplifier performance is in good agreement with calculations from the nonlinear multimode simulation
code. Gyrophase bunching of the electrons is preserved over the long drift region (30 radiation wavelengths) even though no
attempt has been made to minimize the velocity spread of the beam. 相似文献
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A possibility of precise measurement of the electron beam energy using absorption of radiation by electrons in a homogeneous magnetic field for electrons of high energy in the range up to a few hundred GeV, was considered earlier. In this paper, with the purpose of experimental checking of this method in the range of several tens MeV of electrons energies, a possibility of measurement of absolute energy of the electron beam with a relative accuracy up to 10?4, is considered. We take into account influence of the laser beam diffraction, of the spread of electrons over energies, and of the length of formation of radiation absorption in the process of electron beam energy measurement. The laser wavelength and the length of the magnet are chosen depending on the length of photon absorption formation. It is found that the kinematical restrictions on the photon absorption process lead to the selection in angles of propagation of photons, which can be absorbed by the beam electrons. It is shown that parameters of the electron beam will noticeably not vary during the measurement of the energy. 相似文献
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Acceleration and radiation of externally injected electrons in laser plasma wakefield driven by a Laguerre-Gaussian pulse 下载免费PDF全文
By using three-dimensional particle-in-cell simulations, externally injected electron beam acceleration and radiation in donut-like wake fields driven by a Laguerre-Gaussian pulse are investigated. Studies show that in the acceleration process the total charge and azimuthal momenta of electrons can be stably maintained at a distance of a few hundreds of micrometers. Electrons experience low-frequency spiral rotation and high-frequency betatron oscillation, which leads to a synchrotron-like radiation. The radiation spectrum is mainly determined by the betatron motion of electrons. The far field distribution of radiation intensity shows axial symmetry due to the uniform transverse injection and spiral rotation of electrons. Our studies suggest a new way to simultaneously generate hollow electron beam and radiation source from a compact laser plasma accelerator. 相似文献
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本文从单粒子模型出发,对自由电子激光放大器在小信号情形下的工作机理与参量特性进行了比较详细的分析与讨论,结果表明自由电子激光放大器实质上是电子束与快迴旋波的相互作用,而电子在轴向均匀静磁场及横向周期静磁场中运动的迴旋谐振条件对这种相互作用有重大的影响,本文对放大器的参量(如电子束的电压和电流密度、轴向及横向静磁场强度、横向静磁场波长等)与放大器的中心工作频率、放大带宽、小信号增益和放大电磁波的波数的关系进行了数值计算,并指出了最佳设计的途径,经过适当设计,自由电子激光放大器的小信号增益达到10-2厘米-1或1米的e倍距离并有足够的带宽是不难的。
关键词: 相似文献
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De Ninno G Allaria E Coreno M Chowdhury S Curbis F Danailov MB Diviacco B Ferianis M Karantzoulis E Longhi EC Pinayev IV Spezzani C Trovò M Litvinenko VN 《Physical review letters》2008,100(10):104801
Coherent radiation from a relativistic electron beam is a valuable way to overcome the present limitations of conventional lasers and synchrotron radiation light sources. The typical scheme has electrons, directly from a linac, in a single-pass interaction with a laser pulse in the presence of a static undulator magnetic field. We demonstrate that a storage-ring free-electron laser can also achieve harmonic generation (down to 36.5 nm), presenting both experimental and theoretical results, and offer a reliable interpretation of the peculiar underlying physical processes involved. 相似文献
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H.K. Avetissian 《Physics letters. A》1978,67(2):101-104
The quantum modulation of an electron beam in the field of opposite electromagnetic waves, at a frequency equal to the difference of the wave frequencies, and its harmonics, is obtained. The depth of the modulation becomes of order one at relatively small intensities of the laser fields (including a real spreading of the beam). In the case of equal frequencies of the waves (when the Kapitza-Dirac effect occurs particles form a beam. An experiment for obtaining a modulated beam of particles at the frequencies of the laser radiation, and its harmonics, as well as for bunching of particles in the field of a standing wave is suggested. 相似文献