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The effects of monochromatic and polychromatic radiation on human skin and veins are modeled on the basis of the theory of radiation transfer and the theory of heat conduction. Using the criteria of safety and efficiency of treatment, conclusions regarding the optimal parameters of sources of radiation are drawn. 相似文献
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We have developed a theory of X-ray Cerenkov radiation for grazing incidence of relativistic electrons on a thin foil while taking into account absorption, reflection and refraction of radiation. The possibilities for the enhancement of radiation intensity are discussed on the basis of the theory developed. 相似文献
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A quantum mechanical theory of stimulated resonance Raman scattering taking full account of the effects of the incident and scattered radiation on the state and properties of the molecules is developed. The resulting formulas enable the amplification of the scattered radiation and the attenuation of the incident flux to be determined. The conditions under which stimulated Raman scattering produces amplification of radiation are formulated. The range of applicability of the theory, not taking account of the effects of radiation on the properties of the material is discussed. 相似文献
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V. V. Syshchenko N. F. Shul’ga 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(2):217-222
The transition radiation of relativistic electrons in nonuniform media is considered. Based on the equivalent photon method and the eikonal approximation in wave mechanics, a method for describing this process is proposed. For the case in which the permittivity depends on several coordinates, equations for the spectral-angular density of transition radiation are obtained. The main results obtained in the Born and eikonal approximations of the theory of transition radiation are compared. The equations obtained are used to analyze the transition radiation process for a fiberlike target. 相似文献
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从声波的散射理论出发,利用级数展开法得到高斯波束的波束因子,推导其对阻抗边界下离轴球形粒子声辐射力.针对刚性球与液体球两种球形粒子进行数值模拟,与自由空间的情况进行比较.讨论边界反射系数、粒子与边界距离、束腰半径以及离轴角度与距离等对声辐射力的影响.仿真结果表明:边界反射系数的增大会引起声辐射力的增加,但不改变峰值的位置;在合适的频率处,可以产生负向声辐射力;声辐射力随粒子与边界距离呈周期性变化;束腰半径的影响主要体现在中高频;随着粒子偏离传播轴的距离和角度增大,声辐射力明显衰减.该研究为利用高斯波束实现对粒子的操纵提供理论基础. 相似文献
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本文首先根据能量转换理论建立了电磁辐射影响下神经元电流变量模型, 然后结合Hodgkin-Huxley(HH)神经元模型研究了电磁辐射对单个神经元以及耦合神经元放电行为的影响. 结果表明, 随着电磁辐射强度的增大, 神经元放电率逐渐减小, 最后达到一个比较稳定的值. 神经元原有的周期型放电由于辐射强度的增大而逐步过渡到簇放电状态, 并借助动态分岔理论解释了这种放电模式的转换. 同时证明了磁辐射对单个神经元放电的影响可以通过神经元间的耦合传递到临近其他神经元中. 相似文献
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The motion and radiation of electrons moving in a magnetic field at low energy levels are investigated using quantum theory. An important difference between the results obtained and the equations of classical theory is established. It is shown that the radiation essentially depends on the orientation of the particle spins. The existence of a metastable excited state of the electron is revealed. Radiation in super-high fields is demonstrated. 相似文献
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Timothy H. Boyer 《Foundations of Physics》2010,40(8):1102-1116
It is pointed out that relativistic classical electron theory with classical electromagnetic zero-point radiation has a scaling
symmetry which is suitable for understanding the equilibrium behavior of classical thermal radiation at a spectrum other than
the Rayleigh-Jeans spectrum. In relativistic classical electron theory, the masses of the particles are the only scale-giving
parameters associated with mechanics while the action-angle variables are scale invariant. The theory thus separates the interaction
of the action variables of matter and radiation from the scale-giving parameters. Due to this separation, classical zero-point
radiation is invariant under scattering by the charged particles of relativistic classical electron theory. The basic ideas
of the matter-radiation interaction are illustrated in a simple relativistic classical electromagnetic example. 相似文献
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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. 相似文献
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The theory of generation of the low-frequency radiation due to ponderomotive action of a focused laser pulse that is incident on a conductor is developed. Spectral, angular, and energy characteristics of the low-frequency radiation and the spatiotemporal structure of the low-frequency pulse are analyzed. 相似文献
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The action of a strong high-frequency electromagnetic field on a lateral semiconductor superlattice is considered based on the quasi-classical electron transport theory in the self-consistent wave formulation. The theory predicts that a lateral superlattice can emit terahertz radiation wave trains, which are associated with periodic excitation of Bloch oscillations in the superlattice arising because of the development of transient processes in it in a variable self-consistent electric field. The conditions necessary for observing Bloch oscillator radiation were found. The spectral composition of radiation transmitted through the superlattice and the energy efficiency of frequency multiplication related to Bloch oscillator excitation were calculated. 相似文献
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《Physics Reports》2005,409(5):261-359
The features of electromagnetic processes are considered which connected with finite size of space region in which final particles (photon, electron–positron pair) are formed. The longitudinal dimension of the region is known as the formation length. If some external agent is acting on an electron while traveling this distance the emission process can be disrupted. There are different agents: multiple scattering of projectile, polarization of a medium, action of external fields, etc. The theory of radiation under influence of the multiple scattering, the Landau–Pomeranchuk–Migdal (LPM) effect, is presented. The probability of radiation is calculated with an accuracy up to “next to leading logarithm” and with the Coulomb corrections taken into account. The integral characteristics of bremsstrahlung are given, it is shown that the effective radiation length increases due to the LPM effect at high energy. The LPM effect for pair creation is also presented. The multiple scattering influences also on radiative corrections in a medium (and an external field too) including the anomalous magnetic moment of an electron and the polarization tensor as well as coherent scattering of a photon in a Coulomb field. The polarization of a medium alters the radiation probability in soft part of spectrum. Specific features of radiation from a target of finite thickness include: the boundary photon emission, interference effects for thin target, multi-photon radiation. The theory predictions are compared with experimental data obtained at SLAC and CERN SPS. For electron–positron colliding beams following items are discussed: the separation of coherent and incoherent mechanisms of radiation, the beam-size effect in bremsstrahlung, coherent radiation and mechanisms of electron–positron creation. 相似文献
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Egon Marx 《International Journal of Theoretical Physics》1976,15(12):891-899
In this theory, both the advanced and retarded Liénard-Wiechert potentials are used to compute the fields of a charged point particle. The incoming radiation from the advanced fields balances the outgoing radiation of the retarded fields, and we assume that there are no radiation reaction terms in the equations of motion of the particles. We further assume that only retarded fields act on particles through the Lorentz force, and that advanced fields act on antiparticles. This is a theory that is symmetric under time reflection (reversal of the direction of motion plus charge conjugation). 相似文献
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大气对激光传输的影响 总被引:4,自引:0,他引:4
本文分析了激光传输过程中大气这一传输介质对其的影响,由大气的成分出发,采用辐射传输理论描述了大气介质的吸收和散射特性,着重分析了其中对辐射影响最大的两种因素,即大气消光和大气湍流。并建立了大气传输系统的传递函数模型。最后通过LOWTRAN模拟软件包对本文所得的模型进行评估。 相似文献
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对入射等离子体的相对论电子注(REB)在离子通道中可能产生切连科夫(Cherenkov)辐射的问题进行了论证与研究.利用线性理论分析了离子背景下的注-波互作用关系,导出了系统的色散方程与同步辐射条件.结果表明,系统的电磁不稳定性是由离子通道中TM模与电子注模通过电子注耦合所致,其微观机理是离子对电子注的聚焦.对处于运动等离子体状态下的离子-注系统进行了严格地理论分析,获得了通道内辐射波的频偏与波增长率公式,并通过数值模拟计算讨论了系统有关参数对它们的影响.
关键词:
离子通道
等离子体
切连科夫辐射 相似文献
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Robert L. Forward 《General Relativity and Gravitation》1971,2(2):149-159
Summary Some gravitational radiation antenna designs are discussed which are capable of distinguishing between the spin zero scalar
radiation predicted by the Brans-Dicke theory of gravitation and the spin two tensor radiation predicted by the Einstein theory
of gravitation. The antennas will also give information concerning the direction to the source of radiation, and will measure
the polarization of the tensor radiation. The designs consist of symmetric masses with approapriately spaced and oriented
transducers. The transducers are combined to give orthogonal outputs. Linear combinations of these orthogonal outputs then
are uniquely associated with the various possible combinations of radiation type, propagation, direction and polarization,
orientation.
Essay submitted to the 1969 Awards for Essays on Gravity, Gravity Research Foundation, New Boston, New Hampshire. 相似文献
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The surface current method known in the theory of electromagnetic waves diffraction has been generalized to be applied to the problems of diffraction radiation generated by a charged particle moving nearby an ideally-conducting screen in vacuum. An expression for induced surface current density leading to the exact results in the theory of transition radiation has been derived, and by using this expression several exact solutions of diffraction radiation problems are found. Limits of applicability for the earlier known models based on the surface current conception are indicated. Properties of radiation from a semi-plane and from a slit in cylinder are investigated at the various distances to observer. 相似文献