نتایج جستجو برای: plasma instability
تعداد نتایج: 440675 فیلتر نتایج به سال:
Thermal instability of partially ionized plasma is investigated by means of a linear perturbation analysis. According to the previous studies under the one fluid approach, the thermal instability is suppressed due to the magnetic pressure. However, the previous studies did not precisely consider the effect of the ion-neutral friction, since they did not treat the flow as two fluid which is comp...
Energetic electromagnetic emissions by astrophysical jets like those that are launched during the collapse of amassive star and trigger gamma-ray bursts are partially attributed to relativistic internal shocks. The shocks are mediated in the collisionless plasma of such jets by the filamentation instability of counterstreaming particle beams. The filamentation instability grows fastest only if ...
This paper describes the problem of feedback control for stabilization of the plasma vertical instability in a tokamak. Such controllers are typically designed based on a model that assumes the plasma mass m is identically zero while in reality the mass is small but positive. The assumption that m is zero can lead to a controller that appears to be stabilizing according to the massless analysis...
The Caltech experiment described here produces plasmas relevant to both astrophysical and fusion energy studies. A disk-shaped set of electrodes mounted on the inside of a meter-scale vacuum chamber provides the energy to break a neutral gas, provided at the electrodes only, down into a plasma. The plasma starts as eight loops, and then self-organizes into a single magnetically driven collimate...
The dynamics of two counter-streaming electron-positron-ion unmagnetized plasma shells with zero net charge is analyzed in the context of magnetic field generation in GRB internal shocks due to the Weibel instability. The effects of large thermal motion of plasma particles, arbitrary mixture of plasma species and space charge effects are taken into account. We show that, although thermal effect...
The E157 experiment is designed to demonstrate highgradient Plasma Wake Field Acceleration over a significant length. It has been suggested that the electron hose instability of the drive beam will degrade the performance of this experiment because the hosing tailelectrons will not fully sample the highest acceleration field. In this paper a parasitic experiment designed to test the extent of t...
A new ideal magnetohydrodynamic instability is presented. It is shown that linear incompressible Alfvénic disturbances can get over-reflected and exponentially amplified in compressible plasma flows. A simple and transparent stability criterion for a two-layer model is derived. The instability does not require a shear in the flow and may arise for rather moderate sub-Alfvénic flow speeds. It is...
The development of the Weibel instability during the expansion of a thin plasma foil heated by an intense laser pulse is investigated, using both analytical models and relativistic particle-in-cell simulations. When the plasma has initially an anisotropic electron distribution, this electromagnetic instability develops from the beginning of the expansion. Then it contributes to suppress the ani...
Recent discoveries in a helicon plasma show a decrease in equilibrium plasma density as magnetic field strength is increased. This can be explained in the framework of a low frequency electrostatic instability. However, quiescent plasma behavior in helicon sources has been hitherto accepted. To verify the existence of an instability, extensive measurements of fluctuating quantities and losses a...
The propagation of an intense relativistic electron beam through a gas that is self-ionized by the beam's space charge and wakefields is examined analytically and with 3D particle-in-cell simulations. Instability arises from the coupling between a beam and the offset plasma channel it creates when it is perturbed. The traditional electron hose instability in a preformed plasma is replaced with ...
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