A classical relativistic hydrodynamical model for strong EM wave-spin plasma interaction

Based on the covariant Lagrangian function and Euler-Lagrange equation, a set of classical fluid equations for strong EM wave-spin plasma interaction is derived. Analysis shows that the relativistic effects may affect the interaction processes by three factors: the relativistic factor, the time component of four-spin, and the velocity-field coupling. This set of equations can be used to discuss the collective spin effects of relativistic electrons in classical regime, such as astrophysics, high-energy laser-plasma systems and so on. As an example, the spin induced ponderomotive force in the interaction of strong EM wave and magnetized plasma is investigated. Results show that the time component of four-spin, which approaches to zero in nonrelativistic situations, can increase the spin-ponderomotive force obviously in relativistic situation.

Superluminal velocity beyond the scope of application of relativity

People have carried on the extensive researches on the superluminal velocity in experiment and theory, but it is difficult to reach consensus. The biggest problem here is the theory of relativity, which shows that when a object (a matter with mass) reaches or exceeds the speed of light, whose relativistic factor will become infinite or imaginary numbers, so it is impossible to superluminal motion. In fact, although relativity is quite correct quantitative theory, but it has certain limitations. Relativistic effects are the vacuum effects, not the substantive effects. Relativistic physical quantities are only apparent physical quantities expressed through ether(physical vacuum). The substantive physical quantities of an objects are proper physical quantities, which will not vary with the velocity. Moreover the ether in superluminal velocity would lose superfluidity, and thus the superluminal velocity is beyond its scope of application of relativity. Therefore studying superluminal velocity need not scruple the restriction of relativity. Human superluminal activities will involve gravitational shielding, superluminal communication and other supertechnologies.

Collinear Equilibrium Points in the Relativistic R3BP when the Bigger Primary is a Triaxial Rigid Body

This study examines the effect of the relativistic factor as well as the triaxiality effect of the bigger primary on the positions and stability of the collinear points in the frame work of the post-Newtonian approximation. Using semi-analytical and numerical approach the collinear points are found to be unstable. A numerical exploration in this connection, with the Earth-Moon system, reveals that the relativistic factor has an effect on these positions. It is also found that under the combined effect of relativistic factor and triaxiality, the collinear point L1 moves towards the primaries with the increase in triaxiality, while L2 and L3 move away from the bigger primary. It is also seen that in most of the cases in the presence of triaxiality, the effect of relativistic factor on the positions of L1 and L3 is not observable; however it has an observable effect on the position of L2 in the presence of triaxiality except for the case 2.

On the stability of L4,5 in the perturbed relativistic R3BP with a triaxial bigger primary

In the present paper, we endeavor to study the stability of triangular points under the influence of small perturbations in the Coriolis and centrifugal forces, together with the triaxiality of the bigger primary in the framework of the relativistic R3BP. It is observed that the locations of these points are affected by the relativistic factor, triaxiality and a small perturbation in the centrifugal force, but are unaffected by that of the Coriolis force. It is also seen that for these points the range of stability region increases or decreases according as equation (14) without is greater or less than zero.

Second-harmonic generation by an obliquely incident s-polarized laser from a magnetized plasma

Second-harmonic generation by an obliquely incident s-polarized laser from an underdense plasma in the presence of a magnetic field has been investigated analytically. An expression for the relativistic factor γ has been obtained in the presence of magnetic field. The efficiency of second-harmonic radiation η has been obtained as a function of angle of incidence θ, normalized electric field amplitude of laser beam a0, normalized electron density ${\rm \omega} _{\rm p}^2 /{{\rm \omega} ^2}$, and magnetic field b. It is observed that γ increases with b. In turn, the conversion efficiency decreases with an increase in b. It is seen that the conversion efficiency is affected by the magnetic field due to the modified relativistic factor. In the absence of magnetic field, η increases with a0 and θ. However, in the presence of magnetic field, the conversion efficiency starts decreasing as the magnetic field is increased.

FALLING RIGHT WHILE MOVING SLOW: TRUE TESTS OF THE WEAK EQUIVALENCE PRINCIPLE FOR ANTIPARTICLES

A significant question in experimental gravity is the nature of free fall of antiparticles under gravity and elaborate preparations are underway to directly test this with cold antihydrogen. Earlier, the Shapiro delay of supernova 1987A neutrinos was interpreted as testing the weak equivalence principle (WEP). We establish the surprising result that the Shapiro delay of relativistic particles does not test WEP for intrinsic properties or quantum numbers of particles or antiparticles. This is because essentially the entire gravitational mass of the relativistic neutrinos is contributed by kinetic energy, diluting to insignificance any EP violating contribution from intrinsic properties, by the relativistic factor. The crucial message here is that a true test of the WEP involving intrinsic properties of matter or antimatter — the foundation of relativistic gravity — necessarily requires nonrelativistic "cold" matter and antimatter.

Ion acoustic soliton in weakly relativistic magnetized electron–positron–ion plasma

A theoretical investigation was made for the ion acoustic wave in a weakly relativistic magnetized electron-positron-ion warm plasma. A Korteweg-de vries equation (KdV) is derived by using a standard reductive perturbation method. It is found that the presence of ion temperature (σ), ratios of positron-to-electron density (β), electron-to-positron temperature (α), and relativistic factor (Ur) significantly modify solitonic behavior. The authors observed that these parameters considerably change the amplitude and width of the solitary wave.

Nonlinear Thomson backscattering of intense laser pulses by electrons trapped in plasma-vacuum boundary

We present the idea of intensified attosecond X-ray generation based on nonlinear Thomson backscattering of an intense laser pulse by electrons trapped in plasma-vacuum boundary. Two frequency up-conversions due to the relativistic Doppler effect and longitudinal γ-spike effect are analyzed, respectively, where γ is the relativistic factor of the plasma surface. Relativistic resonance heating conditions should be used as a criterion for the experimental design to obtain efficient high-order harmonics and energetic electrons' generation at relatively low laser intensities. Shaping the laser field by proposing a detuned second-harmonic can generate a single attosecond pulse without spectral filtering.

Laser electron accelerator in plasma with adiabatically attenuating density

In this paper, we present a novel kind of electron acceleration mechanism when the trapped electrons are in a wake of plasma with adiabatically attenuating density. Accompanied with the increase of phase velocity βp of the wake owing to the plasma density attenuating adiabatically, the trapped electrons synchronized with the wake will get an additional acceleration besides the synchrotron oscillating acceleration just like in an accelerating elevator. The additional energy gain of the trapped electrons is determined by the value of the relativistic factor γpf = ω/ωp(zf) at the exit zf of the plasma wake. Moreover, the acceleration length is not limited by the dephasing deterministically any more, instead, it is mainly determined by the survivability of the wake. In other words, it is dependent upon the wake instability and its involving energy from driving source.