Abstract:Global oscillations of inhomogeneous plasma with frequencies close to the bounce frequency of ions in mirror traps have been studied. It has been shown that, in some cases, the sound can be reflected from the axial plasma inhomogeneity. The ideal magnetohydrodynamic (MHD) model with ChewGoldberger-Low approximation has been utilized to determine conditions of existence of the standing waves in the mirror-confined plasma. Linearized wave equation for the longitudinal plasma oscillations in thin anisotropic inho… Show more
“…The radial distribution of the azimuthal component of the oscillation electric field has a peak in the region where the density of fast ions reaches a maximum. Such oscillations are similar to the global sound modes which were observed earlier in the GDT device (Skovorodin et al 2013).…”
Section: Discussionsupporting
confidence: 85%
“…Preliminary numerical simulations of a mirror machine with neutral beam injection show that axisymmetric oscillations with the frequency close to the bounce-frequency of sloshing ions between the magnetic mirrors are excited. These oscillations are similar to the global sound modes observed in a GDT device (Skovorodin, Zaytsev & Beklemishev 2013). To study the spatial structure of these oscillations, a set of simulations of plasma with sloshing ions was performed.…”
Section: Axisymmetric Waves In a Plasma With The Population Of Sloshi...supporting
We present the results of numerical simulation by two-dimensional hybrid particle-in-cell code of high-beta plasma with hot ions in an axisymmetric mirror machine. Two particular effects are discussed: the self-rotating of plasma with Maxwellian ions in regime of diamagnetic confinement and the excitation of axisymmetric magnetosonic waves in a high-beta plasma with sloshing ions.
“…The radial distribution of the azimuthal component of the oscillation electric field has a peak in the region where the density of fast ions reaches a maximum. Such oscillations are similar to the global sound modes which were observed earlier in the GDT device (Skovorodin et al 2013).…”
Section: Discussionsupporting
confidence: 85%
“…Preliminary numerical simulations of a mirror machine with neutral beam injection show that axisymmetric oscillations with the frequency close to the bounce-frequency of sloshing ions between the magnetic mirrors are excited. These oscillations are similar to the global sound modes observed in a GDT device (Skovorodin, Zaytsev & Beklemishev 2013). To study the spatial structure of these oscillations, a set of simulations of plasma with sloshing ions was performed.…”
Section: Axisymmetric Waves In a Plasma With The Population Of Sloshi...supporting
We present the results of numerical simulation by two-dimensional hybrid particle-in-cell code of high-beta plasma with hot ions in an axisymmetric mirror machine. Two particular effects are discussed: the self-rotating of plasma with Maxwellian ions in regime of diamagnetic confinement and the excitation of axisymmetric magnetosonic waves in a high-beta plasma with sloshing ions.
“…Other phenomena specific to this particular experiment are the high-amplitude global acoustic mode oscillations [21] traced in the diamagnetic signal (figure 12, top) and in more detail by magnetic probe diagnostics. The oscillations are represented by machine-scale variations of plasma pressure with a frequency of ∼100 kHz.…”
Section: Experiments With Broad Heating Profilementioning
confidence: 86%
“…The longitudinal wavelength of the observed acoustic mode is estimated to be equal to the overall mirror-to-mirror distance; the azimuthal spectrum is represented exclusively by the m = 0 mode. Without ECRH these oscillations are saturated at low level and are usually awakened by other instabilities such as the Alfvén ioncyclotron instability and die away after 4-5 periods leaving no trace in the diamagnetic signal [21]. In discharges with ECR heating, however, the amplitude of these oscillations is several times higher inducing unprecedented ∼5% variations in the diamagnetic signal of the fast ions during the whole microwave pulse (figure 12, top).…”
Section: Experiments With Broad Heating Profilementioning
This paper summarizes the results of experiments on electron cyclotron resonance heating (ECRH) of plasma obtained at the axially symmetric magnetic mirror device gas dynamic trap (GDT) (Budker Institute, Novosibirsk). The main achievement is the demonstration of plasma discharges with extremely high temperatures of bulk electrons. According to the Thomson scattering measurements, the on-axis electron temperature averaged over several sequential shots is 660 ± 50 eV with peak values exceeding 900 eV in a few shots. This corresponds to an at least threefold increase as compared to previous experiments both at the GDT and at other comparable machines, thus demonstrating the maximum quasi-stationary (∼0.6 ms) electron temperature achieved in open traps. The breakthrough is made possible with the successful implementation of a sophisticated ECRH scheme in addition to standard heating by neutral beams (NBs). Another important result is the demonstration of the significantly increased lifetime of NB-driven fast particles with the application of ECRH, leading to a 30% higher plasma energy content at the end of the discharge. All available data including the previously demonstrated possibility of plasma confinement with β as high as 60%, allows us to consider fusion applications of axially symmetric magnetic mirror machines on a realistic basis.
“…In experiment on the GDT the longitudinal oscillations of plasma were observed [1,2]. It has typically zero angular wave-number, seems to be radially correlated and has the frequency about 100 kHz.…”
Abstract. Nonstationary kinetic approach has been used to study the influence of the high beta on the dispersion of slow magnetic sound wave. It is shown that in plasma with sloshing ions the oscillating unstable mode could exist even in limit of cold electrons if beta is high enough. The threshold of the instability depends strongly on the distribution of ions near injection energy. The unstable wave is maintained by the perturbation of magnetic field and become aperiodic mirror mode far beyond the instability threshold.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.