Propagation and scattering of lasers present new phenomena and applications when the plasma medium becomes strongly magnetized. With megaGauss magnetic fields, scattering of optical lasers already becomes manifestly anisotropic. Special angles exist where coherent laser scattering is either enhanced or suppressed, as we demonstrate using a coldfluid model. Consequently, by aiming laser beams at special angles, one may be able to optimize laserplasma coupling in magnetized implosion experiments. In addition, magnetized scattering can be exploited to improve the performance of plasmabased laser pulse amplifiers. Using the magnetic field as an extra control variable, it is possible to produce optical pulsesmore »
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We show that backward Raman amplification in plasma can efficiently compress a temporally incoherent pump laser into an intense coherent amplified seed pulse, provided that the correlation time of the pump is longer than the inverse plasma frequency. One analytical theory for Raman amplification using pump beams with different correlation functions is developed and compared to numerical calculations and particleincell simulations. Since incoherence on scales shorter than the instability growth time suppresses spontaneous noise amplification, we point out a broad regime where quasicoherent sources may be used as efficient lownoise Raman amplification pumps. As the amplified seed is coherent, Ramanmore »Cited by 1Full Text Available

A cascaded sequence of photon acceleration stages using the instantaneous creation of a plasma density gradient by flash ionization allows the generation of coherent and chirped ultraviolet and xray pulses with independently tunable frequency and bandwidth. The efficiency of the cascaded process scales with 1/ω in energy, and multiple stages produce significant frequency upconversion with gasdensity plasmas. Lastly, chirping permits subsequent pulse compression to fewcycle durations, and output frequencies are not limited to integer harmonics.Cited by 1

Here, for hot spots compressed at constant velocity, we give a hydrodynamic stability criterion that describes the expected energy behavior of nonradial hydrodynamic motion for different classes of trajectories (in ρR — T space). For a given compression velocity, this criterion depends on ρR, T, and dT/d(ρR) (the trajectory slope) and applies pointwise so that the expected behavior can be determined instantaneously along the trajectory. Among the classes of trajectories are those where the hydromotion is guaranteed to decrease and those where the hydromotion is bounded by a saturated value. We calculate this saturated value and find the compression velocitiesmore »

In a variety of magnetized plasma geometries, it has long been known that highly charged impurities tend to accumulate in regions of higher density. This “collisional pinch” is modified in the presence of additional forces, such as those might be found in systems with gravity, fast rotation, or nonnegligible space charge. In the case of a rotating, cylindrical plasma, there is a regime in which the radially outermost ion species is intermediate in both mass and charge. As a result, this could have implications for fusion devices and plasma mass filters.

Here, we present a simple model for the turbulent kinetic energy behavior of subsonic plasma turbulence undergoing isotropic threedimensional compression, which may exist in various inertial confinement fusion experiments or astrophysical settings. The plasma viscosity depends on both the temperature and the ionization state, for which many possible scalings with compression are possible. For example, in an adiabatic compression the temperature scales as 1/L ^{2}, with L the linear compression ratio, but if thermal energy loss mechanisms are accounted for, the temperature scaling may be weaker. As such, the viscosity has a wide range of net dependencies on the compression.more »Cited by 1

A wavedriven rotating torus is a recently proposed fusion concept where the rotational transform is provided by the E × B drift resulting from a minor radial electric field. This field can be produced, for instance, by the RFwavemediated extraction of fusionborn alpha particles. In this paper, we discuss how macroscopic force balance, i.e., balance of the thermal hoop force, can be achieved in such a device. We show that this requires the inclusion of a small plasma current and vertical magnetic field and identify the desirable reactor regime through free energy considerations. We then analyze particle orbits in thismore »Cited by 2Full Text Available

Large amplitude waves in magnetized plasmas, generated either by external pumps or internal instabilities, can scatter via threewave interactions. While threewave scattering is well known in collimated geometry, what happens when waves propagate at angles with one another in magnetized plasmas remains largely unknown, mainly due to the analytical difficulty of this problem. In this study, we overcome this analytical difficulty and find a convenient formula for threewave coupling coefficient in cold, uniform, magnetized, and collisionless plasmas in the most general geometry. This is achieved by systematically solving the fluidMaxwell model to second order using a multiscale perturbative expansion. Themore »Cited by 1Full Text Available
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