Speaker
Jack Davies Hare
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.4015.pdf
Particle acceleration in high energy density magnetic reconnection
experiments
J. W. D. Halliday1 , J. D. Hare1 , L. G. Suttle1 , S. V. Lebedev1 , S. N. Bland1 , T. A. Clayson1 ,
E. Tubman1 , D. R. Russell1 , S. Pikuz2,3 , and T. Shelkovenko2,3
1 Blackett Laboratory, Imperial College, London, SW7 2AZ, United Kingdom
2 Cornell University, Ithaca, USA
3 Lebedev Institute of Physics, Moscow, Russia
Magnetic reconnection is important in astrophysical and space plasmas, from the strongly
driven and collisionless interaction of planetary magnetospheres with the solar wind; to the
more weakly driven and collisional flows found in the solar convective zone. In these plasmas,
fast particles are a key signature of reconnection. In this presentation, we describe experimental
results from a novel reconnection platform [1, 2] which are consistent with the direct accel-
eration of electrons by the reconnecting electric field. The platform uses the MAGPIE pulsed
power generator to produce plasma inflows (uin ∼ 50 km/s) that carry a strong azimuthal mag-
netic field (Bin ∼ 3T ) and persist for many hydrodynamic timescales ( Ttotal ∼ 500 ns Thydro
10 ns). These experiments are typically diagnosed using laser interferometry, Faraday rotation,
and Thomson scattering.
For the results presented here thermal, magnetic, and ram pressure are all dynamically sig-
nificant (βdyn ∼ βth ∼ 1); the Lundquist number is S ∼ 120; and the ratio of the ion skin depth
to the layer width is di /δ ∼ 1. This regime is distinct and complimentary to laser driven and
gas discharge reconnection experiments. In this work we enhanced our diagnostic capability
to study non-thermal electron acceleration by the reconnecting electric field. Metal foils were
placed in the path of the accelerated electrons, which collisionally excited atomic transitions,
producing characteristic X-Ray spectra. These were diagnosed using spherically bent crystal
X-Ray spectroscopy and filtered pinhole imaging. Time resolved measurements were obtained
using fast silicon diode detectors. We observed spectra consistent with a significant population
of super thermal particles, exceeding the thermal velocity of the plasma by over an order of
magnitude. By combining these fast particle diagnostics with our existing diagnostic suite, we
can enhance our growing understanding of the link between astrophysical observations and lab-
oratory experiments.
[1] Suttle, L. G., Hare, J. D., Lebedev, S. V. et. al. (2016). PRL, 116, 225001
[2] Hare, J. D., Suttle, L. G., Lebedev, S. V. et. al. (2017). PRL, 118, 85001
