In this talk I will present results of recent experimental studies of supersonic, radiatively cooled plasma jets, performed at the pulsed power MAGPIE facility (1.5MA, 250ns) at Imperial College. The experiments are scalable to astrophysical flows in that critical dimensionless numbers such as the plasma collisionality, the plasma beta, Reynolds number and the magnetic Reynolds number are all in the astrophysically appropriate ranges. The presentation will include discussion of the dynamics of magnetically driven jets, in particular formation of episodic outflows. The experimental results show the periodic ejections of magnetic bubbles naturally evolving into a heterogeneous jet propagating inside a channel made of self-collimated magnetic cavities. Interaction of the jets with ambient medium (He, Ar, Kr gases) leads to formation of bow-shocks, and effects of radiative cooling on the morphology of these shocks will be discussed. Quantitative information on the plasma parameters in all these experiments is provided by several spatially and temporally resolved diagnostics, including direct measurements of flow velocities using Doppler shift of Thomson scattering spectra. Studies of the properties of radiatively cooled shocks, performed using ablation plasma flow in wire array z-pinches, will be also presented.
1. A. Ciardi, S.V. Lebedev, A. Frank et al., The Astrophysical Journal, 691: L147–L150 (2009)
2. F.A. Suzuki-Vidal, S.V. Lebedev, S.N. Bland et al., Physics of Plasmas, 17, 112708 (2010).
3. F.A. Suzuki-Vidal, M. Bocchi, S.V. Lebedev et al., Physics of Plasmas, (2012 – in press).
*) In collaboration with A. CIARDI, F.A. SUZUKI-VIDAL, M. BOCCHI, A. HARVEY-THOMSON, P. de GROUCHY, J, SKIDMORE, L. SUTTLE, G. SWADLING, G. BURDIAK, S.N. BLAND, J.P. CHITTENDEN, G. HALL, A. FRANK, E. G. BLACKMAN, C. STEHLE, M. CAMENZIND. This research was sponsored by the EPSRC Grant No.EP/G001324/1 and by the US DOE Cooperative Agreements No. DE-F03-02NA00057 and No. DE-SC-0001063.