A review of the dense Z-pinch

Plasma Phys. Control. Fusion 53 (2011) 093001
Topical Review
Figure 96. Deflection of a supersonic plasma jet by a plasma wind blowing from right to left,
illustrated in a laser schlieren image 343 ns after the start of the current on MAGPIE. Shock-like
features can be identified [715, figure 2].
Lebedev et al [715] showed how the approximately current-free precursor plasma from an
overmassed tungsten conical array can form a jet with an axial velocity similar in magnitude
to that of astrophysical jets, namely 200 km s −1 . In this case L and t of the two systems scale
in the same way, and the Euler equations, i.e. the dissipationless hydrodynamic equations,
∂ρ
+ ∇·(ρv) = 0, (8.10)
∂t
( )
∂v
ρ
∂t + (v ·∇)v =−∇p, (8.11)
∂p
+ v ·∇p =−γp∇·v (8.12)
∂t
remain the same if L and t are scaled by the same factor [709]. In ideal MHD an additional
term −µ −1
0
B × (∇ ×B) arises together with Faraday’s law combined with Ohm’s law
∂B
=∇×(v × B), (8.13)
∂t
which also formally remains the same. If, furthermore, the parameters v, B, ρ and p are the
same, in the two systems, the dimensionless parameters R e , R m and P e also all scale with the
same factor as L or t. If this scale factor is A, the energy required to drive a scaled experiment
scales as A 3 which makes laboratory experiments possible. Ryutov and Remington [716] call
this a ‘perfect’ hydrodynamic similarity as transport coefficients are identical in both systems,
including compositional effects. Gardiner et al [717] have presented MHD models of jets,
while Ciardi et al has extended modelling of jets to 3D [718].
Continuing with magnetic field free jets from the precursor phase of a conical wire-array
Z-pinch, Lebedev et al [719] caused the jet to interact with a cross-wind plasma produced by
radiative ablation of a thin plastic foil placed above the anode. This cross-wind had a density
of 10 24 m −3 and a velocity of 2 × 10 4 ms −1 .A4 ◦ deflection of the jet occurred and increased
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