Energetic Particle Confinement Research Articles

Equilibrium, Stability, and Deeply Trapped Energetic Particle Confinement Calculations for l = 2 Torsatron/Heliotron Configurations

This paper studies confinement properties of 1 = 2 torsatron/heliotron configurations with number of toroidal field periods, M, in the range of 10 to 14. This involves the calculation of zero-current and flux-conserving equilibria; stability against Mercier modes and low-n ideal modes, with n denoting the toroidal mode number; and orbit confinement of deeply trapped energetic particles. Optimization of both magnetohydrodynamic (MHD) and transport properties is pursued under the condition of plasma aspect ratio A = R/a {ge} 7, with R denoting the major radius and a the average plasma radius. For configurations with M, {le} 12, an average MHD beta limit of 4 to 5% is possible. The addition of a quadrupole field improves the confinement of trapped particles at zero pressure, but particle losses increase with increasing beta. This loss is less severe if the vacuum magnetic axis is shifted slightly inward. A configuration with M = 10, a coil pitch parameter p{sub c} in the range 1.25 to 1.30, and an added quadrupole field satisfies the beta and energetic particle confinement requirements for the next generation of large torsatron/heliotron devices.

Acceleration and confinement of energetic particles in the 1980 June 7 solar flare

Pulsations with large amplitude and duration have been observed during the hard X-ray and microwave radio bursts associated with the 1980 June 7 solar flare. The high time resolution measurements of 20-800 keV X-rays were made with the X-ray spectrometers aboard the ISEE 3 and P78-1 spacecraft. The radio measurements, covering metric to microwave wavelengths, were made at the Nobeyama and Toyokawa observatories in Japan. The temporal evolution of the X-ray and radio spectra and the polarization and spatial structure of the microwave source have been examined. The following interpretation is found to be consistent with the observations: (1) the variations in the electron acceleration/injection spectrum are responsible for the observed variations in the hard X-ray and microwave emissions; (2) the locations of the hard X-ray and microwave sources are probably different, the X-ray source being located at a lower altitude.

Further observational support for the limited‐latitude magnetodisc model of the outer Jovian magnetosphere

The distinction between the magnetic anomaly model of the outer Jovian magnetosphere (Dessler and Vasyliunas, 1979; Vasyliunas and Dessler, 1981) and the magnetodisc model (as, for example, discussed most recently by Goertz (1981)) is reviewed, and a further observational comparison of the two models is pointed out. The comparison involves the latitudinal variation of the intensity of energetic charged particles confined near the magnetic equatorial plane. Because of this confinement, there should be a direct relationship between the maximum latitude excursion (relative to the magnetic equatorial plane) made by a spacecraft during one 10‐hour planetary rotation period and the ratio of the maximum intensity observed in the magnetic equatorial plane to the minimum intensity observed off the equator. Thus if the maximum latitude excursion is large, the minimum between two maxima should be quite deep. If the maximum latitude excursion is known, a scale height for the energetic particle confinement can be estimated from observed maximum‐to‐minimum ratios. The two magnetospheric models (magnetic anomaly and magnetodisc) in general predict different maximum latitude excursions. For the outbound passes of Voyagers 1 and 2, these predictions are combined with observations of energetic particle intensities (Krimigis et al., 1979a, b) to calculate the confinement scale heights for the energetic particles. For the magnetodisc model, the scale height is generally less than 2 RJ and is a weakly decreasing function of r, in excellent quantitative agreement with the scale height derived from a combination of simple MHD theory and a magnetic field model based on Pioneer 10 outbound magnetic field measurements (Goertz, 1976). The magnetic anomaly model, on the other hand, yields a scale height which apparently increases to large values at large radial distances. Furthermore, when the calculation is reversed for the magnetodisc model, so that the observed max/min ratio is combined with the theoretically predicted scale height to yield a maximum latitude excursion for each of the current sheet encounters, it is found that the resultant current sheet latitude agrees very well with the current sheet latitude estimated on other grounds, namely, the timing of the intensity maxima. Moreover, as shown by Goertz (1981), excursions of this current sheet latitude away from the nominal value of 9.6° are reasonably well associated with periods of enhanced solar wind dynamic pressure.