Laboratory experiments related to the solar wind and the magnetosphere

Abstract

The increasing number of laboratory experiments related to the solar wind and the magnetosphere calls for a critical review of the conditions under which a laboratory experiment can provide information about space phenomena. Naturally, the starting point is a discussion of the problem of physical similarity. For a unified presentation of the several sets of scaling laws that have been used, it is convenient to use the similarity laws of the Vlasov theory as a reference system. Clearly, the biggest obstacle for a strict reproduction of the solar‐wind‐magnetosphere interaction in the laboratory is collisional interaction. In the solar wind at the earth's orbit, strict simulation is possible only for phenomena with a dimension of the order of a few hundred kilometers or smaller, such as the bow shock structure. A discussion of the existing terrella experiments shows that most of them obtain similarity by scaling the interplanetary field and the geomagnetic field differently. This determines the processes for which quantitative agreement can be expected, e.g., the shape of the frontal part of the cavity boundary and the approximate shape and position of the bow shock. Strict similarity can be achieved in simulating the structure of the bow shock wave. The over‐all ranges of the shock parameters of seven collision‐free shock experiments discussed cover substantial parts of the bow shock parameter ranges. A comparative discussion of the magnetic‐field profiles of the estimated shock width and of the appearance of oscillatory structures shows strong resemblances between space and laboratory observations. Several other experiments related to the solar wind and the magnetosphere are also listed.

Efficient injection of an intense positron beam into a dipole magnetic field

“…Most often, a spherical magnetic dipole, sometimes called 'terrella' (little Earth), was used. Early work in this direction has been summarized in [11] and more recent results are, for example, in [12]. Here, we consider a slightly different idea, namely to manipulate particle trajectories using a tailored, static electric field to inject particles into the confinement region via the E B drift.…”

Grand challenges in low-temperature plasma physics

“…The energy stored in the dynamical behavior of the Sun's complex magnetic field structures is occasionally released in dramatic disruptions (Coronal Mass Ejections) producing large space storms in the magnetosphere of the Earth and investigated in the laboratory for nearly a century in "Terrella experiments" [5,6]. These storms can have major consequences for communications and impact almost every aspect of our life through telecommunications, telephones or when simply driving to the shops using a Global Positioning System (GPS).…”

Impulsive Flux Transfer Events and Solar Flares

“…For example, there is Vlasov scaling, modified Vlasov scaling, MHD scaling, etc. (Schindler 1966(Schindler , 1969. Success of a given choice of a similarity law depends on understanding in some depth the nature of the particular problem at hand ci priori.…”