Synchrotron radiation of electrons in periodic weakly-focusing magnetic fields

The dynamics of an electron in a weakly focusing accelerator with rectilinear gaps is studied by the method of averaging and by the perturbation method. The asymptotic solutions found are used to investigate the angular properties of the synchrotron radiation of electrons. It is shown that vertical betatron oscillations play an important role in the formation of the angular distributions of the radiation.     

VUV resonant transition radiation from relativistic electrons

The modified radiator for generation of the resonant transition radiation from relativistic electrons is presented. This radiator consists of a set of small thin foils inclined with respect to the trajectory of an emitting electron. It is shown that the photoabsorption of the emitted photons is almost completely suppressed in the considered scheme. Therefore, the possibility of generating intense beams of quasimonochromatic vacuum ultraviolet (VUV) quanta by the proposed method appears.     

周期会切磁场聚焦强流相对论带状电子束的理论分析和粒子模拟

对低幅值、短周期、有偏置磁极的周期会切磁场中300 keV,3 kA带状电子束的传输进行了理论分析和粒子模拟。给出了将波导宽度考虑在内的轴向均匀带状电子束的空间电荷场和作用在有限厚度的带状电子束的短边和宽边上的聚焦力的表达式,并利用束匹配的方法得到了磁场的幅值和周期,以及电子束通道的宽度和高度等参数。最后根据理论计算的结果进行了３维粒子模拟验证,结果表明：束宽边上聚焦良好,而在短边上带状电子束的轴向有限长效应使得聚焦力与散焦力沿轴向不能完全匹配,在束包络上产生了Betatron振荡,但在300 mm的距离上传输效率仍能达到98%以上,说明有偏置磁极的周期会切磁场聚焦强流带状电子束在理论上是可行的。     

Synchrotron radiation of a relativistic magneton

The classical theory of synchrotron radiation of an electrically neutral relativistic particle with a large intrinsic magnetic moment is considered (g-factor much greater than unit). The spectral-angular composition and polarization of the radiation are studied. The magneton radiation self-polarization time is calculated. It is shown that identical results follow from the Ternov-Bagrov-Khapaev quantum theory constructed on the basis of the Dirac-Pauli equation for a neutron.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 38–41, May, 1986.The authors express their gratitude to V. G. Bagrov for his interest in the study and valuable remarks.     

X-ray radiation from nonlinear Thomson scattering of an intense femtosecond laser on relativistic electrons in a helium plasma

We have generated x-ray radiation from the nonlinear Thomson scattering of a 30 fs/1.5 J laser beam on plasma electrons. A collimated x-ray radiation with a broad continuous spectrum peaked at 0.15 keV with a significant tail up to 2 keV has been observed. These characteristics are found to depend strongly on the laser strength parameter a(0). This radiative process is dominant for a(0) greater than unity at which point the relativistic scattering of the laser light originates from MeV energy electrons inside the plasma.     

等离子体中相对论电子的同步曲率辐射特性研究

根据同步曲率辐射理论推导了在等离子体环境中,不同磁场条件下的相对论性电子的吸收系数和发射系数表达式，计算了电子的发射强度，并且在此基础上研究了同步曲率辐射机制的脉泽效应.研究了两种磁场位型，第一种是强度均匀但弯曲的磁场，第二种是偶极磁场，结果发现了一些偶极磁场下特有的辐射特性.考虑到在天体的环境下电子具有的不同的能谱分布，分别选用了三种典型的能谱分布(幂率分布，高斯分布，热分布)进行了研究，通过计算负吸收和脉泽放大效应在发射强度上的表现后， 发现在某些天体物理环境中，同步曲率辐射在等离子体中的确存在脉泽放大效应.这些研究结果对太阳系中行星外层辐射的研究和宇宙中的射电高亮温度等问题的研究可能提供有益的帮助. 关键词： 同步曲率辐射 负吸收 脉泽效应     

Spectral structure of polarization radiation from relativistic electrons in aluminum

Collective effects in polarization bremsstrahlung generated by relativistic electrons in a polycrystalline aluminum foil are studied experimentally on the basis of the 2.4-MeV electron accelerator installed at the Institute of Nuclear Physics (Moscow State University, Moscow). A peak structure found in this polarization bremsstrahlung for the first time is in agreement with theoretical predictions. __________ Translated from Yadernaya Fizika, Vol. 63, No. 11, 2000, pp. 2097–2100. __________ Translated from Yadernaya Fizika, Vol. 63, No. 11, 2000, pp. 2097–2100.     

Large-angle channeling radiation from relativistic electrons in optically transparent crystals

In the work within the frame of quantum electrodynamics are obtained new formulae describing the large-angle photon emission from channeled electrons with taking into account of the dispersion of refractive index. Calculations based on these formulae show that the spectral and angular distributions of large-angle optical and ultraviolet radiation from planar channeled sub-GeV electrons in optically transparent crystal reflect the band structure of transverse energy levels of channeled electrons. Comparison with ordinary Cherenkov radiation spectrum reveals that channeling (depending on the beam energy) leads to sufficient change of the large-angle emission spectrum.     

Synchrotron radiation of electrons trapped in earth's magnetosphere

Relatively large fluxes of trapped electrons with energy above several tens of MeV in the inner radiation belt, established according to low altitude satellite measurements, invoked the question of their production of synchrotron radiation in geomagnetic field. Based on experimental data on electrons, rough estimate of the spectral density of synchrotron radiation at the Equator is obtained in the region of maximum emissivity. Relatively low value of the radiation flux implies that only precise measurements at 1 GHz allowing to measure the directivity of emissions may be relevant.     

Synchrotron radiation from a longitudinally polarized relativistic spinning particle in pseudoclassical theory

The spin dependence of the intensity and polarization of synchrotron radiation from a longitudinally polarized particle moving at a constant speed along a circle in a uniform magnetic field is investigated within the pseudoclassical approach.     

Theory of radiation from relativistic electrons channelled in mixed valence systems

A method has been formulated for studying the character of the radiation emitted from relativistic electrons channelled axially in mixed valence systems. It has been found that the frequency of the channelling radiation varies periodically with time and that the intensity of radiation decreases in such an oscillatory manner which is relatively more complex than the nature of usual quantum beats.     

Tunable few-cycle and multicycle coherent terahertz radiation from relativistic electrons

We report the generation of tunable, narrow-band, few-cycle and multicycle coherent terahertz (THz) pulses from a temporally modulated relativistic electron beam. We demonstrate that the frequency of the THz radiation and the number of the oscillation cycles of the THz electric field can be tuned by changing the modulation period of the electron beam through a temporally shaped photocathode drive laser. The central frequency of the THz spectrum is tunable from ～0.26 to 2.6 THz with a bandwidth of ～0.16 THz.     

Electromagnetic radiation of relativistic electrons in thick crystals

Angular distributions of soft gamma quanta and spectra of electron radiation intensity are compared in diamond crystals of various thickness for axial orientation. Narrow directionality of the soft gamma quanta and a weak dependence of angular width of the distribution on crystal thickness are noted. For axial orientation the angular width of the soft gamma quantum distribution comprises ± 2_L for diamond, silicon, and tungsten crystals. Radiation losses into the collimator _c = 1/ for axial orientation increases with thickness and reach their maximum value at t 0.1 radiation length. It is shown experimentally that maximum values of radiation loss into the cone ^–1 can be achieved in crystals of the light-elements.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 32–38, September, 1986.     

Stimulated emission by relativistic electrons in magnetic undulators

A quantum mechanical solution to the problem of stimulated emission in axial and flat magnetic undulators, including electron spin properties, is presented.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 45–49, December, 1985.In conclusion, the author considers it his pleasant duty to thank Professors I. M. Ternov and V. R. Khalilov for their help.     

Radiation of relativistic electrons in a magnetic undulator

Expressions are obtained for the spectral-angular characteristics of the radiation in two limiting cases: 1 and 1 ( is the angle of deflection of the electron in the field, and is the energy of the electron in units of mc²). It is shown that in the latter case the maximum of the radiation occurs at higher harmonics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 88–91, October, 1973.In conclusion the authors thank Professor A. A. Sokolov for useful discussions.     

Investigation of resonance diffractive radiation from relativistic electrons in conducting periodic targets

Optical resonance diffractive and transition radiation from 200-MeV electrons in conducting periodic targets with spaced strips are investigated experimentally at the Tomsk synchrotron. The orientation and spectral properties of the radiation are measured.