The linear stability of drift waves in a poloidally rotating tokamak plasma is considered. The derived dispersion relation features a peaking of the diamagnetic frequency which gives the drift modes an irreducible two-dimensional character. We then show that inverse Landau damping can be suppressed and even stabilized, if the flow's shear is strong. Even though the instability, excited by the Landau resonance, is stronger at a high velocity shear for positive rotation velocities, effects due to the rotation of the plasma can reverse the sign and induce damping of the two-dimensional drift modes. This stabilizing mechanism works only for positive rotation velocities. For negative rotation velocities, we show that only modes with high poloidal mode numbers are unstable.

It is well known that energetic protons having a ring-type, anisotropic velocity distribution can generate low-frequency electromagnetic waves, propagating nearly transverse to the geomagnetic field lines, in the ring current region of the Earth's magnetosphere by exciting mode 1 and mode 2 non-resonant instabilities and a resonant instability. In this paper, detailed investigations of the resonant and non-resonant instabilities are conducted as a function of plasma parameters such as ring speeds, electron temperatures, magnetic field strength and wave propagation directions. Our analysis is for parameters corresponding to the ring current region of the Earth's magnetosphere.

Fluctuations in ambient shear flow exhibit interesting transient phenomena. Shear flow produces not only Kelvin–Helmholtz modes (global exponential instabilities represented by point spectra) but also local algebraic instabilities associated with multiple continuous spectra. Since the generating operator is non-Hermitian, the orthogonality of eigenmodes is broken, and unresolvable mode couplings (resonances) bring about secular behavior (algebraic instability). We analyze electrostatic fluctuations in a magnetized non-neutral (single species) plasma where the electrostatic potential parallels the stream function. This secular behavior is reproduced by solving the initial value problem with a renormalization method.

Compression of plasmas with laser pulses in the 10-kJ range produced densities in the range of 1000 times that of the solid state, where however the temperatures within a few hundred eV were rather low. This induced the fast ignitor scheme for central or peripheral deposition of some 10-kJ ps laser pulses on conventional $n_{\rm s}$-precompressed DT plasma of 3000 times solid-state density. We present results where the ps ignition is avoided and only a single-event conventional compression is used. Following our computations of volume ignition and the excellent agreement with measured highest fusion gains of volume compression, we found conditions where compression to 5000 times that of the solid state and by using laser pulses of 10 MJ produce volume ignition with temperatures between 400 and 800 eV only for high-gain volume ignition.

As is known, the minimum magnetic energy state for a frozen plasma, subject to the infinite topological constraints, corresponds to a nonlinear force-free field. The magnetic flux invariance in ideal magnetohydrodynamics is possible in important astrophysical applications. We develop a method for explicitly obtaining a minimum energy state starting from an arbitrary initial state. This method does not require the explicit use of the invariance of the differential magnetic helicities. It is particularly useful when the minimum magnetic energy state for the given topological structure is unique. We show examples of the application of the method for this kind of system.

Low-frequency dusty plasma waves with frequencies much smaller than the frequency of charging collisions of plasma particles with dust particles are considered, taking into account elastic and charging collisions of plasma particles with dust and with neutrals. The usual dust sound waves with an upper frequency equal to the dust plasma frequency are found to be present only for wavelengths much smaller than the plasma particle effective mean free path due to the effective collision frequency. The effective collision frequency is found to be inversely proportional to the square root of the product of the charging frequency and the frequency of particle momentum losses, involving processes due to elastic plasma particle–dust collisions, and collisions with neutrals. It is shown that when the wavelength of the wave is much larger than the mean free path for effective collisions the properties of the waves are different from those previously considered. A negative mass instability is found in this domain of frequencies when the effective mean free path of ions is larger than the effective mean free path of electrons. In the absence of neutrals this appears to be possible only if the temperature of ions exceeds the electron temperature. This can occur in laboratory experiments and space plasmas but not in plasma-etching experiments. In the absence of instability a new dust oscillation, a dust charging mode, is found the frequency of which is almost constant over a certain range of wavenumbers. It is inversely proportional to the dust mass and charging frequency of the dust. A new dust electron sound wave is found for frequencies less than the frequency of the dust charging mode. The velocity of the dust electron sound wave is determined by the electron temperature but not the ion temperatures, as for the usual dust sound waves, with the electron temperature exceeding the ion temperature substantially.

This paper deals with the linear response of a plasma in a one-dimensional bounded geometry under the action of a time-periodic electric field. The nonlinear Vlasov equation is solved by following the characteristic curves until they reach the boundary of the domain, where the distribution function of the incoming particles is supposed to be known and independent of time. Then, a first-order Taylor expansion in the velocity variable is performed, thanks to an approximation of the exact characteristics by the unperturbed ones. The resulting first-order correction to the distribution function is finally integrated over velocities to yield the dielectric function. The special case of a plane wave for the electric field is examined and the results are compared with the more usual unbounded case: the integral does not present any singularity in the vicinity of resonant particles and the dielectric function depends on the distance to the boundary and tends to the usual infinite-geometry value when this distance tends to infinity, with a rate of convergence proportional to its inverse square root. Numerical examples are provided for illustration.