Density distribution of solar wind protons and “loaded” ions in the shock layer ahead of a cometary ionosphere

We propose a simple method that allows the density fields of solar wind protons and heavy ions of cometary origin (“loaded” ions) in the solar wind-cometary ionosphere interaction region to be separated from the general density field calculated within the framework of a single-fluid model. The method is based on the assumption that the velocities of both components are identical. We analyze the density fields in the solar wind obtained in this way before and after the passage of the bow shock ahead of the cometary ionosphere and make a comparison with the distributions measured with various instruments onboard the Giotto spacecraft when it flew past Comet Halley and calculated on the basis of more complex multi-fluid models.     

Formation of episodic magnetically driven radiatively cooled plasma jets in the laboratory

We report on experiments in which magnetically driven radiatively cooled plasma jets were produced by a 1 MA, 250 ns current pulse on the MAGPIE pulsed power facility. The jets were driven by the pressure of a toroidal magnetic field in a “magnetic tower” jet configuration. This scenario is characterized by the formation of a magnetically collimated plasma jet on the axis of a magnetic “bubble”, confined by the ambient medium. The use of a radial metallic foil instead of the radial wire arrays employed in our previous work allows for the generation of episodic magnetic tower outflows which emerge periodically on timescales of ～30 ns. The subsequent magnetic bubbles propagate with velocities reaching ～300 km/s and interact with previous eruptions leading to the formation of shocks.