Circularly polarized waves in a plasma with vacuum polarization effects
J. Lundin, L. Stenflo, G. Brodin, M. Marklund, P. K. Shukla
本文将大振幅圆极化波沿外磁场传播的理论推广到真空极化效应。一个一般的色散关系，团结以前的结果，推导出来。
The theory for large amplitude circularly polarized waves propagating along an external magnetic field is extended in order to include also vacuum polarization effects. A general dispersion relation, which unites previous results, is derived.
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Features of ion acceleration by circularly polarized laser pulses
采用粒子模拟方法研究了圆偏振超短超强激光脉冲驱动MeV离子源的特性。预测的特点包括高效率，大离子密度，低发散和飞秒持续时间的可能性。与线偏振脉冲的情况进行了比较。
Low-Frequency Instability of Linearly and Circularly-Polarized-Microwave-Field Produced Plasmas
在非相对论极限下，研究了强脉冲线极化和圆极化微波场对气体的击穿。得到了线极化和圆极化微波场与电子相互作用产生的电子分布函数，表明电子分布函数是非平衡的和各向异性的。找到一般的色散关系，并分析它，我们首先得到的低频振荡，其次，我们表明，不稳定性可能会发展在上述系统。它将表明，对于线性极化的微波场，这种不稳定性可能总是发展，但对于圆极化场，它的增长只有当离子密度高于临界密度。
Radiation Pressure Acceleration of Thin Foils with Circularly Polarized Laser Pulses
本文描述了一种新的方法，即用10^20 W/cm ^2以上的强激光束对薄箔进行辐射压力加速。利用圆偏振光可以非常高的效率产生扩展到GeV能量的高单能质子束。质子束具有非常小的发散角（小于4度）。这种新方法允许构建具有超短粒子爆发的超紧凑质子和离子加速器。
Exact solution for large amplitude circularly polarized electromagnetic waves in incompressible spin quantum Hall magnetohydrodynamics
结果表明，不可压缩自旋量子霍尔磁流体力学允许圆极化电磁波的传播的精确解。该解是在流体速度和磁场之间的一个条件下得到的，该条件消除了麦克斯韦方程组中的非线性项。由于与自旋的耦合，传播模式取决于磁场的振幅。从完整的解决方案，小和大波数的限制进行了研究，获得线性和非线性自旋修改模式。
Wave-particle interaction is a key process in particle diffusion in collisionless plasmas. We look into the interaction of single plasma waves with individual particles and discuss under which circumstances this is a chaotic process, leading to diffusion. We derive the equations of motion for a particle in the fields of a magnetostatic, circularly polarized, monochromatic wave and show that no chaotic particle motion can arise under such circumstances. A novel and exact analytic solution for the equations is presented. Additional plasma waves lead to a breakdown of the analytic solution and ch…
Dynamics of ultra-intense circularly polarized solitons under inhomogeneous plasmas
研究了非均匀等离子体中超强圆偏振孤子的动力学行为。相互作用的麦克斯韦和相对论流体动力学方程组建模，并解决了全隐式能量守恒的数值方案。结果表明，增强等离子体背景可以减弱和反射传输中的弱孤子，这与现有的基于弱密度响应假设的研究结果一致。然而，我们发现，当遇到越来越大的背景时，超强孤子被很好地捕获并保持静止。这一发现有可能应用于强激光场的捕获和放大。
We show that a commonly accepted transparency threshold for a thin foil in a strong circularly polarized normally incident laser pulse needs a refinement. We present a new analytical model, which correctly accounts for laser absorption. The refined threshold is determined not solely by the laser amplitude, but other parameters are equally or even more important. Our predictions are in a perfect agreement with PIC simulations. The refined criterion is crucial for configuring laser plasma experiments in the high field domain. Besides, an opaque foil steepens the pulse front, this can be importan…
Directed Coulomb Explosion regime of ion acceleration from mass limited targets by linearly and circularly polarized laser pulses
本文研究了超薄双层（高Z/低Z）质量限制靶离子加速的定向库仑爆炸机制。在这种情况下，激光脉冲从被照射的光斑中抽空电子，并在激光脉冲传播的方向上加速剩余的离子核。然后，移动的离子核由于过量的正电荷而爆炸，形成移动的电荷分离场，该电荷分离场加速来自第二层的质子。质量有限目标的利用增加了加速的有效性。为了保证线偏振脉冲和圆偏振脉冲的最佳加速效果，应选择不同的激光靶结构参数。
Non-linear Breit-Wheeler $e^+e^-$ pair production and its crossing channel - the non-linear Compton process - in the multi-photon regime are analyzed for linearly and circularly polarized short laser pulses. The contribution of multi-photon processes to total cross sections is determined and we also show that (i) the azimuthal angular distributions of outgoing electrons in these processes differ on a qualitative level, and (ii) they depend on the polarization properties of the pulses. A finite carrier envelope phase (CEP) leads to a non-trivial non-monotonic behavior of the azimuthal angle dis…
Circularly polarized modes in magnetized spin plasmas
研究了磁化等离子体中电子的内禀自旋对圆极化波传播的影响。新的本征模被识别，其中一个在电子回旋频率以下传播，一个在自旋进动频率以上传播，另一个接近自旋进动频率。后者对应于铁磁体在一定条件下的自旋模。在电子的非相对论运动中，即使当外部磁场$B_{0}$低于量子临界磁场强度时，自旋效应也变得明显，即，$B_{0}<$ $B_{Q} =4.4138\times10^{9}\, \mathrm{T}$且电子密度满足$n_{0} \gg n_{c}\simeq10^{32}$ m $^{-3}$。讨论了电子自旋（顺磁）共振（ESR）在等离子体诊断中的重要性。
Particle dynamics and spatial $e^-e^+$ density structures at QED cascading in circularly polarized standing waves
我们提出了一个全面的分析，纵向粒子漂移的驻波圆偏振波在极端强度时，量子辐射反应（RR）的影响应占。为了深入了解这种现象的物理学，我们进行了比较研究，考虑了朗道-利夫希茨或量子校正形式的RR力，包括光子发射随机性的情况。结果表明，圆偏振和线偏振的情况是定性不同的。此外，粒子动力学的特定特征对在真空中通过反向传播激光脉冲中的量子电动力学（QED）级联产生的电子-正电子（$e^-e^+$）密度的空间结构具有强烈的影响。考虑QED效应的3D PIC模拟证实了不同对等离子体结构的实现。
Tunable Circularly Polarized Terahertz Radiation from Magnetized Gas Plasma
理论和模拟结果表明，在双色激光驱动器的传输方向上对气体靶施加静磁场，可以产生圆偏振或椭圆偏振的太赫兹辐射。辐射频率由$\sqrt{ω_p^2+{ω_c^2}/{4}} + {ω_c}/{2}$确定，其中$ω_p$是等离子体频率，$ω_c$是电子回旋频率。随着B场的增加，辐射由单周期宽带波形变为连续窄带发射。在高B场情况下，辐射强度与$ω_p^2/ω_c$成比例。B场提供辐射频率、谱宽和场强的可调谐性。
It has recently been suggested that two counter-propagating, circularly polarized, ultra-intense lasers can induce a strong electron spin polarization at the magnetic node of the electromagnetic field that they setup. We confirm these results by considering a more sophisticated description that integrates over realistic trajectories. The electron dynamics is weakly affected by the variation of power radiated due to the spin polarization. The degree of spin polarization differs by approximately 5\% if considering electrons initially at rest or already in a circular orbit. The instability of tra…
Attospiral generation upon interaction of circularly polarized intense laser pulses with cone-like targets
利用三维粒子等离子体模拟程序，研究了圆柱形等离子体中高强度脉冲的产生。由于靶是旋转对称的，因此考虑了圆偏振激光脉冲在空心圆锥靶轴上的传播。大的入射角和恒定的有质动力压导致相对论电子的纳米聚束，这是激光驱动同步辐射的原因。本文提出了一种数值方法来确定引起attopulses存在的相干辐射的来源和方向。谐波谱中的强度调制可用推广到高阶γ尖峰区的相干同步辐射模型来描述。高次谐波的空间分布类似于螺旋形状，其被聚焦到目标后面的小体积中。
Kinetically modified parametric instabilities of circularly-polarized Alfven waves: Ion kinetic effects
在离子和无质量电子流体的一维Vlasov描述的框架内，研究了均匀背景等离子体中平行传播的圆偏振有限振幅Alfven波的参数不稳定性，从而包含了纵向动力学扰动（离子朗道阻尼）。本发明的制剂还包括霍尔效应。所得结果与以往的相关分析吻合较好，表明当纵向动力学效应“被动”作用时，纵向动力学效应在Alfven波的参数不稳定性中起重要作用。此外，存在的动力学参数不稳定性被确认为小子波波的制度。这些不稳定性的增长率是敏感的离子温度。本文的公式和结果可应用于在太阳风和地球前震区观测到的阿尔芬波。
A novel deflection effect of an intense laser beam with spin angular momentum is revealed theoretically by an analytical modeling using radiation pressure and momentum balance of laser plasma interaction in the relativistic regime, as a deviation from the law of reflection. The reflected beam deflects out of the plane of incidence with a deflection angle up to several milliradians, when a non-linear polarized laser, with the intensity $I_0\sim10^{19}$W/cm$^2$ and duration around tens of femtoseconds, is obliquely incident and reflected by an overdense plasma target. This effect originates from…
Generation of intense circularly polarized attosecond light bursts from relativistic laser plasmas
我们研究了相对论周期激光脉冲与过密等离子体表面相互作用产生的纳米电子束的阿秒光脉冲的偏振特性。粒子模拟表明，产生的阿秒脉冲的偏振态取决于入射脉冲的偏振态、脉冲宽度、载波包络相位以及等离子体尺度长度。通过控制激光和等离子体参数，在不牺牲产生效率的前提下，具有方位角$θ^i=10^\circ$的线偏振激光脉冲可以产生具有方位角$|θ^r_{\rm atto}|\approx61^\circ$和椭圆率$σ^r_{\rm atto}\approx0.27$的椭圆偏振阿秒脉冲，而具有$σ^i\approx0.36$的椭圆偏振激光脉冲可以产生具有$σ^r_{\rm atto}\approx0.95$的近圆偏振阿秒脉冲。该结果为台式圆偏振XUV光源作为具有阿秒尺度时间分辨率的探测器提供了一种新的途径。
A way to considerably enhance terahertz radiation, emitted in the interaction of intense mid-infrared laser pulses with atomic gases, in both the total energy and the electric-field amplitude is suggested. The scheme is based on the application of a two-color field consisting of a strong circularly polarized mid-infrared pulse with wavelengths of $1.6÷4\,μ{\rm m}$ and its linearly or circularly polarized second harmonic of lower intensity. By combining the strong-field approximation for the ionization of a single atom with particle-in-cell simulations of the collective dynamics of the generate…
Propagation features of circularly polarized (CP) electromagnetic waves in magnetized plasmas are determined by the plasma density and the magnetic field strength. This property can be applied to design a unique plasma photonic device for intense short-pulse lasers. We have demonstrated by numerical simulations that a thin plasma foil under an external magnetic field works as a polarizing plate to separate a linearly polarized laser into two CP waves traveling in the opposite direction. This plasma photonic device has an advantage for generating intense CP waves even with a relativistic amplit…
Context. Kink waves are routinely observed in coronal loops. Resonant absorption is a well-accepted mechanism that extracts energy from kink waves. Nonlinear kink waves are know to be affected by the Kelvin-Helmholtz instability. However, all previous numerical studies consider linearly polarized kink waves. Aims. We study the properties of circularly polarized kink waves on straight plasma cylinders, for both standing and propagating waves, and compare them to the properties of linearly polarized kink waves. Methods. We use the code MPI-AMRVAC to solve the full 3D Magnetohydrodynamic (MHD) eq…
Enhanced collimated GeV monoenergetic ion acceleration from a shaped foil target irradiated by a circularly polarized laser pulse
采用多维粒子模拟方法，研究了1022 W/cm ^2圆偏振激光脉冲辐照下金属箔的离子加速过程。当箔最初在横向方向上成形以匹配激光强度分布时，与通常的平坦靶相比，靶的中心部分可以均匀加速更长的时间。有效地抑制了靶变形和不期望的等离子体加热。加速离子束的最终能谱得到显著改善。准直GeV准单能离子束携带多达18%的激光能量的观察在多维模拟。辐射阻尼效应也检查在模拟中。
A scheme for generating intense high-harmonic optical vortices is proposed. It relies on spin-orbit interaction of light when a relativistically-strong circularly polarized laser pulse irradiates a micro-plasma-waveguide. The intense laser field drives a strong surface wave at the inner boundary of the waveguide, which leads to high-order harmonic generation as the laser traveling inside. For a circularly polarized drive laser, the optical chirality is imprinted to the surface wave, which facilitates conversion of spin angular momentum of the fundamental light into orbital angular momenta of t…
We show that the Weibel or currente filamentation instability can lead to the emission of circularly polarized radiation. Using particle-in-cell (PIC) simulations and a radiation post-processing numerical algorithm, we demonstrate that the level of circular polarization increases with the initial plasma magnetization, saturating at ~13% when the magnetization, given by the ratio of magnetic energy density to the electron kinetic energy density, is larger than 0.05. Furthermore, we show that this effect requires an ion-electron mass ratio greater than unity. These findings, which could also be …
Scalar and fermionic particle pair production in rotating electric fields is investigated in the nonperturbative multiphoton regime. Angular momentum distribution functions in above-threshold pair production processes are calculated numerically within quantum kinetic theory and discussed on the basis of a photon absorption model. The particle spectra can be understood if the spin states of the particle-antiparticle pair are taken into account.
QED cascades induced by circularly polarized laser fields
本文给出了超高强度圆极化场中慢电子引发的电子-正电子-光子级联的蒙特卡罗模拟结果，并对结果进行了讨论。我们的结果证实了先前的定性估计[A.M. Fedotov等人，PRL 105，080402（2010）]瀑布的形成。这种级联现象揭示了光场对电子和正电子的加速所导致的能量和动力学量子参数恢复的新性质，并可能成为超高强度激光与物质相互作用的主要特征。我们的方法包括辐射摩擦作用于单个电子和正电子。
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