Similarity between blackbody and synchrotron radiation analyzed by Tsallis entropy

It is believed that blackbody and bremsstrahlung are completely different phenomena. However, their spectral shapes are somewhat similar to each other. We demonstrate that synchrotron radiation spectra, which are relativistic magnetic bremsstrahlung, can be approximated by blackbody radiation through Tsallis entropy under the dulite gas approximation at Tsallis non‐extensive parameter q = 1.05. The error of mean square is 4 × 10^?6 within the range of 5 × 10⁴ eV without adjusting any parameters. This approximation will be applied to more complex bremsstrahlung such as an X‐ray tube. Copyright © 2012 John Wiley & Sons, Ltd.     

Synchrotron radiation spectrum for galactic-sized plasma filaments

The radiation spectrum for synchrotron-emitting electrons in galactic-sized Birkeland current filaments is analyzed. It is shown that the number of filaments required to thermalize the emission spectrum to blackbody is not reduced when a non-Maxwellian electron distribution is assumed. If the cosmic background radiation (CBR) spectrum (T=2.76 K) is due to absorption and re-emission of radiation from galactic-sized current filaments, higher-order synchrotron modes are not as highly self absorbed as lower-order modes, resulting in a distortion of the blackbody curve at higher frequencies. This is especially true for a non-Maxwellian distribution of electrons for which the emission coefficient at high frequencies is shown to be significantly less than that for a Maxwellian distribution. The deviation of the CBR spectrum in the high-frequency regime may thus be derivable from actual astrophysical parameters, such as filamentary magnetic fields and electron energies in the model     

Thermodynamic Properties of an Atom Inside a Kerr Nonlinear Blackbody

Thermodynamic properties of a Kerr nonlinear blackbody (KNB) are investigated. It is found that below a transition temperature T _c , the free energy of a KNB radiation is larger than that in a normal blackbody. At the transition from KNB radiation state to a normal blackbody radiation state, the photon system undergoes a first-order phase transition. The thermodynamic system of an atom interacting with a KNB radiation bath is also investigated by using a thermodynamic perturbation theory. It is found that below a transition temperature T _c , the increment of the free energy of the atom is larger than that in a normal blackbody. Above T _c , the KNB becomes a normal blackbody, and the properties in a KNB turn to be the same as those in normal blackbody radiation.     

新一代高温黑体和同步辐射装置及其在地外太阳光谱辐照度测量中的应用

在地外太阳光谱辐照度测量和大气定量遥感等项研究的推动下,近二、三十年,国际上光谱辐射计量技术发展十分迅速。基于先进的高温技术、优异的高温热解石墨材料和独特的设计,全俄光学物理测量研究所(VNIIOFI)研制出温度高达3 200～3 500 K、具有高均匀性和高稳定性的大面积普朗克高温黑体光源。基于低温绝对辐射计的滤光片辐射计迭代测温技术,使高温黑体温度测量不确定度小于0.5 K。在德国物理技术研究院(PTB),将这种高温黑体直接用于国际空间站地外太阳光谱测试仪器(SOLSPEC)的辐射定标,定标综合不确定度小于0.5%～1%。2008年德国物理技术研究院(PTB)建成名为计量光源(MLS)的新一代专用同步辐射存储环并投入使用。为调节同步辐射的光谱分布,稳态下其能量可设置为105～630 MeV任意值,相应特征波长随之从735 nm改变至3.4 nm。为在不改变光谱分布情况下改变光强,电子束流可调节 11个量级,即从 1个存储电子(相当于1 pA)到200 mA。美国国家标准技术研究院(NIST)在同步辐射紫外辐射装置(SURF Ⅲ)3号光束线上建立了使用同步辐射的光谱辐照度定标装置(FICUS),为紫外传递标准光源定标,光谱范围200～400 nm,相对测量不确定度1.2% (k=2)。新一代同步辐射装置为地外太阳光谱辐照度测量仪器,如SUSIM,SOLSTICE,SBUV,SIM和SOLSPEC等,短波段高精度辐射定标奠定了技术基础。该文描述新型高温黑体和同步辐射装置的建立与发展,光谱辐照度和光谱辐亮度标准的传递及国际比对并评述它们在太阳光谱辐照度测量中的应用。     

Sudden Vanishing of Atomic Dipole-Squeezing in a Kerr Nonlinear Blackbody

The dynamics of atomic dipole momentum and atomic dipole-squeezing effect are investigated inside a Kerr nonlinear blackbody. It is found that in a Kerr nonlinear blackbody, the atomic dipole momentum and its squeezing effect are heavily dependent on the Kerr nonlinear coefficient. It is also found that below a transition temperature T _c , the dipole momentum and its squeezing effect in a Kerr nonlinear blackbody can vanish much faster with time than those in a normal blackbody. Above T _c , the Kerr nonlinear blackbody becomes a normal blackbody, and the dynamics of the atomic dipole momentum and its squeezing effect behaves as those in normal blackbody radiation. The physical origin of the sudden-vanishing phenomenon in a Kerr nonlinear blackbody is also discussed.     

Spectral Energy Density in a Kerr Nonlinear Blackbody

In a Kerr nonlinear blackbody, bare photons with opposite wave vectors and helicities are bound into pairsand unpaired photons are transformed into a new kind of quasiparticle, the nonpolariton. The nonpolariton system constitutes free thermal radiation in the blackbody. The present paper investigates the spectral energy density of the thermal radiation. It is found that the spectral energy density of a Kerr nonlinear blackbody is larger than that of a normal blackbody.     

Spectral Energy Density in a Kerr Nonlinear Blackbody

In a Kerr nonlinear blackbody, bare photons with opposite wave vectors and helicities are bound into pairs and unpaired photons are transformed into a new kind of quasiparticle, the nonpolariton. The nonpolariton system constitutes free thermal radiation in the blackbody. The present paper investigates the spectral energy density of the thermal radiation. It is found that the spectral energy density of a Kerr nonlinear blackbody is larger than that of a normal blackbody.     

大气层外核爆炸X射线辐射场特性研究

 X射线被认为是大气层外反导栏截武器的主要破坏因素。在航天器结构材料的辐射损伤计算中，需要核爆炸X射线辐射场的数学模式。从Planck黑体谱出发，提出按温度梯度分层的归一化黑体谱组合模式，给出X射线的释放能量及辐射脉冲，从而建立了大气层外核栏截X射线辐射场特性的数学模式。     

On parton distributions in a photon gas

A solution to the problem of parton distributions in a gas of photons with blackbody spectrum is proposed. The cosmic microwave background radiation is considered as a particular case. The survival probability of ultra-high energy neutrinos traveling through this radiation is calculated.     

Thermodynamics of Phase Transitions of a Kerr Nonlinear Blackbody

We study the thermodynamics of phase transitions of a blackbody whose interior is filled by a Kerr nonlinear crystal. There is a transition temperature To, above which the Kerr nonlinear blackbody is in the normal thermal radiation state, and below which it is in the squeezed thermal radiation state. At To, the Gibbs free energy of the two phases is continuous but the entropy density of the two phases is discontinuous. Hence, there is a jump in the entropy density and this leads to a latent heat density. The photon system undergoes a first-order phase transition from the normal to the squeezed thermal radiation state.     

Quasiprobability distribution in a Kerr-nonlinear blackbody

In a Kerr-nonlinear blackbody, bare photons with opposite wave vectors and helicities are bound into pairs and unpaired photons are transformed into a new kind of quasiparticle, the nonpolariton. The nonpolariton system constitutes free thermal radiation in the blackbody. In this paper, the quasiprobability (Q function) distribution of thermal radiation is investigated. Non-classical effects of quadrature squeezing have been observed. The structure of nonpolaritons is unsteady and governed by the temperature. The phase space of the photon system is considered and found that in the transition from the normal to the squeezed thermal radiation state, the phase symmetry of the photon system is spontaneously broken.     

Modified radiation laws of a rectangular Kerr nonlinear blackbody

A Kerr nonlinear blackbody (KNB) is a new kind of blackbody in which bare photons with opposite wave vectors and helicities are bound into pairs and unpaired photons are transformed into nonpolaritons. In the present paper, we focus our investigation on the modified radiation laws, such as Planck and Stefan-Boltzmann radiation laws, of a rectangular KNB. Besides, the case of a KNB with no symmetry axes is also discussed. Finally, we make a numerical calculation of modified radiation laws of a cubic KNB under appropriate conditions, and we consider this work may lay the foundation for the experimental verification of the model of a KNB.     

Finite-size corrections to the radiation laws of a Kerr nonlinear blackbody

In a Kerr nonlinear blackbody (KNB), bare photons with opposite wave vectors and helicities are bound into pairs and unpaired photons are transformed into nonpolaritons. The nonpolariton system can constitute free thermal radiation in the blackbody. The present paper investigates the radiation of a KNB in a cavity of finite-size. For a given geometry, we obtain explicit expressions of the modified Planck and Stefan-Boltzmann blackbody radiation laws as a function of the temperature, size and shape of the cavity by using semiclassical techniques. Moreover, we discuss these corrections of a spherical KNB and the range of parameters (temperature and size of the cavity) in which these effects are accessible to experimental detection. Finally, we calculate the finite-size corrections (FSCs) under these conditions, and this work may lay the foundation for the experimental verification of a KNB.     

一种红外目标模拟器黑体辐射源选型的计算方法

在光电系统测试中目标模拟器是必不可少的测试设备,黑体辐射源是红外目标模拟器的关键部件,它的选型直接影响着红外目标模拟器的性能。从黑体探测灵敏度与系统探测灵敏度的关系,推导出黑体辐射源的温度计算公式,以此计算黑体辐射源所需的最低温度点。通过仿真验证了计算方法的正确性,为黑体辐射源的选型提供了理论依据。     

双色反射技术在温度测量上的应用

本文以铁镍合金为例,介绍了一种测量金属表面温度的光学测量方法。试验以黑体为反射辐射源,采用FTIR光谱辐射计测量了试样在中温状态的发射辐射以及包含了黑体反射能量的有效辐射。通过建立包含反射辐射的方程组,并运用MATLAB内建的求根模型求解得到了试样表面温度。     

电子磁矩对同步辐射频谱的修正

本文从偶极子辐射场的Heaviside-Feynman表达式出发, 用经典的电动力学方法推导了考虑内禀磁矩影响后的相对论电子辐射频谱分布的表达式, 并对做匀速圆周运动的极端相对论性电子的同步辐射, 计算了两个偏振方向上的考虑磁矩修正后的辐射谱. 计算结果表明对于特征频率为ω_c的同步辐射, 如果ħω_c≥10 keV, 内禀磁矩对辐射的修正是可观的. 通过同步辐射的内禀磁矩修正, 本文讨论了电子束极化度与辐射场偏振度的依赖关系, 并基于此关系提出一种测量电子束极化度的新方法. 关键词： 同步辐射 电子内禀磁矩 同步辐射偏振度 束流极化度     

大气层外核爆炸X－射线辐射场特性研究

Ｘ射线被认为是大气层外反导栏截武器的主要破坏因素。在航天器结构材料的辐射损伤计算中，需要核爆炸Ｘ射线辐射场的数学模式。从Ｐｌａｎｃｋ黑体谱出发，提出按温度梯度分层的归一化黑体谱组合模式，给出Ｘ－射线的释放能量及辐射脉冲，从而建立了大气层外核栏截Ｘ－射线辐射场特性的数学模式     

High-accuracy measurement of atomic polarizability in an optical lattice clock

Presently, the Stark effect contributes the largest source of uncertainty in a ytterbium optical atomic clock through blackbody radiation. By employing an ultracold, trapped atomic ensemble and high stability optical clock, we characterize the quadratic Stark effect with unprecedented precision. We report the ytterbium optical clock's sensitivity to electric fields (such as blackbody radiation) as the differential static polarizability of the ground and excited clock levels α(clock) = 36.2612(7) kHz?(kV/cm)(-2). The clock's uncertainty due to room temperature blackbody radiation is reduced by an order of magnitude to 3×10(-17).     

Analogy between first-order phase transitions and blackbody radiation

The analogy between blackbody radiation and a phase equilibrium between vapor and liquid is drawn by deriving the Clapeyron equation in which the two probability distributions of blackbody radiation play the role of the two phases. The pressure of one of these distributions, which becomes negative at sufficiently high photon energies, is analogous to a negative pressure tending to break up a liquid. A similar type of critical phenomenon should be observed for blackbody radiation.     

环境辐射对目标热辐射特性测试的影响

把落到目标上的总的环境辐射等效成一个温度为T₀的黑体辐射,研究了环境辐射改变时对热成象系统灵敏度方程的影响,从而从理论上证明了用改变环境辐射的办法可以测定目标的比辐射率。给出了用红外测温仪测定环境等效黑体温度T₀的方法和实验结果。给出了用红外测温仪测定目标比辐射率的一种新方法及实验结果。对于环境辐射不能忽略时如何用比辐射计测定目标的真实温度作了方法性和原理性的讨论。对于如何用测温仪测定地物对太阳的光谱反射率也作了方法性和原理性的讨论。 关键词：