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Recently, there has been a surge of interest in nonequilibrium collective quantum models, where particle dispersion and spin are examples of effects taken into account. Here, we derive a kinetic plasma model containing fermion exchange effects. Exchange interactions are of great importance in many systems and have no classical analogy. Our model therefore constitutes a possible probe of collective quantum phenomena in other regimes. As an example, we consider the influence of the exchange effect on low-frequency dynamics, in particular ionacoustic waves. Comparisons lo related computational techniques are given and the differences are highlighted. Furthermore, we discuss the applicability of our model, its limitations, and possible extensions. [ABSTRACT FROM AUTHOR]

The nonlinear propagation of two-dimensional (2D) quantum ion-acoustic waves (QIAWs) is studied in a quantum electron-ion plasma. By using a 2D quantum hydrodynamic model and the method of multiple scales, a new set of coupled nonlinear partial differential equations is derived which governs the slow modulation of the 2D QIAW packets. The oblique modulational instability (MI) is then studied by means of a corresponding nonlinear Schrödinger equation derived from the coupled nonlinear partial differential equations. It is shown that the quantum parameter H (ratio of the plasmon energy density to Fermi energy) shifts the MI domains around the kθ -plane, where k is the carrier wave number and θ is the angle of modulation. In particular, the ion-acoustic wave (IAW), previously known to be stable under parallel modulation in classical plasmas, is shown to be unstable in quantum plasmas. The growth rate of the MI is found to be quenched by the obliqueness of modulation. The modulation of 2D QIAW packets along the wave vector k is shown to be described by a set of Davey-Stewartson-like equations. The latter can be studied for the 2D wave collapse in dense plasmas. The predicted results, which could be important to look for stable wave propagation in laboratory experiments as well as in dense astrophysical plasmas, thus generalize the theory of MI of IAW propagations both in classical and quantum electron-ion plasmas. [ABSTRACT FROM AUTHOR]

The gauge invariant electromagnetic Wigner equation is taken as the basis of a fluid-like system describing quantum plasmas, derived from the moments of the gauge invariant Wigner function. The use of the standard, gauge-dependentWigner function is shown to produce inconsistencies if a direct correspondence principle is applied. The propagation of linear transverse waves is considered and it is shown to be in agreement with the kinetic theory in the long-wavelength approximation, provided that an adequate closure is chosen for the macroscopic equations. A general recipe to solve the closure problem is suggested. [ABSTRACT FROM AUTHOR]

Starting from the Pauli Hamiltonian operator, we derive scalar quantum kinetic equations for spin-1/2 systems. Here, the regular Wigner twostate matrix is replaced by a scalar distribution function in extended phase space. Apart from being a formulation of significant interest, such a scalar quantum kinetic equation makes the comparison with classical kinetic theory straightforward and lends itself naturally to currently available numerical Vlasov and Boltzmann schemes. Moreover, while the quasi-distribution is a Wigner function in regular phase space, it is given by a Q-function in spin space. As such, nonlinear and dynamical quantum plasma problems are readily handled. Moreover, the issue of gauge invariance is treated. [ABSTRACT FROM AUTHOR]

Abstract: A set of quantum hydrodynamic equations are derived from the moments of the electrostatic mean-field Wigner kinetic equation. No assumptions are made on the particular local equilibrium or on the statistical ensemble wave functions. Quantum diffraction effects appear explicitly only in the transport equation for the heat flux triad, which is the third-order moment of the Wigner pseudo-distribution. The general linear dispersion relation is derived, from which a quantum modified Bohm–Gross relation is recovered in the long wave-length limit. Nonlinear, traveling wave solutions are numerically found in the one-dimensional case. The results shed light on the relation between quantum kinetic theory, the Bohm–de Broglie–Madelung eikonal approach, and quantum fluid transport around given equilibrium distribution functions. [Copyright &y& Elsevier]

We consider a dusty plasma where dust particles have a magnetic dipole moment. A Hall-MHD type of model, generalized to account for the intrinsic magnetization, is derived. The model is shown to be energy conserving, and the energy density and flux are derived. The general dispersion relation is then derived, and we show that kinetic dust-Alfvén waves exhibit instability for a low dust and ion temperature and high dust density. We discuss the implication of our results. [ABSTRACT FROM AUTHOR]

Advances in the generation of relativistic intensity pulses with wavelengths in the X-ray regime, through high harmonic generation from near-critical plasmas, open up the possibility of X-ray driven wakefield acceleration. The similarity scaling laws for laser plasma interaction suggest that X-rays can drive wakefields in solid materials providing TeV/cm gradients, resulting in electron and photon beams of extremely short duration. However, the wavelength reduction enhances the quantum parameter χ, hence opening the question of the role of non-scalable physics, e.g., the effects of radiation reaction. Using three dimensional Particle-In-Cell simulations incorporating QED effects, we show that for the wavelength λ = 5 nm and relativistic amplitudes a 0 = 10 –100, similarity scaling holds to a high degree, combined with χ ∼ 1 operation already at moderate a 0 ∼ 50 , leading to photon emissions with energies comparable to the electron energies. Contrasting to the generation of photons with high energies, the reduced frequency of photon emission at X-ray wavelengths (compared with that at optical wavelengths) leads to a reduction in the amount of energy that is removed from the electron population through radiation reaction. Furthermore, as the emission frequency approaches the laser frequency, the importance of radiation reaction trapping as a depletion mechanism is reduced, compared with that at optical wavelengths for a0 leading to similar χ. [ABSTRACT FROM AUTHOR]

Two signatures of quantum effects on radiation reaction in the collision of a ${\sim}$GeV electron beam with a high intensity (${>}3\times 10^{20}~\text{W}~\text{cm}^{-2}$) laser pulse have been considered. We show that the decrease in the average energy of the electron beam may be used to measure the Gaunt factor $g$ for synchrotron emission. We derive an equation for the evolution of the variance in the energy of the electron beam in the quantum regime, i.e. quantum efficiency parameter $\unicode[STIX]{x1D702}\not \ll 1$. We show that the evolution of the variance may be used as a direct measure of the quantum stochasticity of the radiation reaction and determine the parameter regime where this is observable. For example, stochastic emission results in a 25 % increase in the standard deviation of the energy spectrum of a GeV electron beam, 1 fs after it collides with a laser pulse of intensity $10^{21}~\text{W}~\text{cm}^{-2}$. This effect should therefore be measurable using current high-intensity laser systems. [ABSTRACT FROM AUTHOR]

Abstract: Two different quantum processes are considered in a perturbed vacuum cavity: time refraction and dynamical Casimir effect. They are shown to be physically equivalent, and are predicted to be unstable, leading to an exponential growth in the number of photons created in the cavity. The concept of an effective Unruh acceleration for these processes is also introduced, in order to make a comparison in terms of radiation efficiency, with the Unruh radiation associated with an accelerated frame in unbounded vacuum. [Copyright &y& Elsevier]

In quantum electrodynamics, photon–photon scattering gives rise to self-interaction terms in Maxwell''s equations. The effect will be non-zero for electromagnetic waves trapped between regions of conducting material, such as two plasma layers. It is shown numerically that this trapping in conjunction with photon–photon scattering can yield self-compression of electromagnetic waves. We discuss the relevance of our results. [Copyright &y& Elsevier]