The Z-pinch, or the radially inward pressure of electric currents

Left: Pinched aluminum can, produced from a pulsed magnetic field created by rapidly discharging 2 kilojoules from a high voltage capacitor bank into a 3-turn coil of heavy gauge wire. Photo by Bert Hickman. GFDL.

Right: A photograph of a section of the crushed lightning rod first described by J.A. Pollock and S. Barraclough, 1905, Proc. R. Soc. New South Wales 39, 131. They correctly described the crushing mechanism as a result of the interaction of the large current flowing in the conductor with its own magnetic field. Photo by Brian James. GFDL.

The following diagram shows how pinches work (applied to fusion reaction)

The following two papers present evidence that what look like galaxy-sized jets might actually be magnetically self-confined (that is, pinched) plasma filaments in glow mode.

• A. ~L. Peratt, “The evidence for electrical currents in cosmic plasma,” IEEE Transactions on Plasma Science, vol. 18, pp. 26-32, 1990.
  [Bibtex]

  @Article{1990ITPS...18...26P,
    Title                    = {The evidence for electrical currents in cosmic plasma},
    Author                   = {{Peratt}, A.~L.},
    Journal                  = {IEEE Transactions on Plasma Science},
    Year                     = {1990},
  
    Month                    = feb,
    Pages                    = {26-32},
    Volume                   = {18},
  
    Abstract                 = {With the advent of fully three-dimensional, fully electromagnetic, particle-in-cell simulations, investigations of Birkeland currents and magnetic-field-aligned electric fields have become possible in plasmas not accessible to in situ measurement, i.e., in plasmas having the dimensions of galaxies or systems of galaxies. The necessity for a three-dimensional electromagnetic approach derives from the fact that the evolution of magnetized plasmas involves complex geometries, intense self-fields, nonlinearities, and explicit time-dependence. A comparison of the synchrotron radiation properties of simulated currents to those of extragalactic sources provides observational evidence for galactic-dimensional Birkeland currents.},
    Adsnote                  = {Provided by the SAO/NASA Astrophysics Data System},
    Adsurl                   = {http://adsabs.harvard.edu/abs/1990ITPS...18...26P},
    Doi                      = {10.1109/27.45499},
    File                     = {1990ITPS---18---26P.pdf:1990ITPS---18---26P.pdf:PDF},
    Keywords                 = {Birkeland Currents, Cosmic Plasma, Electric Current, Galactic Evolution, Particle In Cell Technique, Plasma Physics, Biot Method, Electromagnetism, Field Aligned Currents, Isophotes, Microwaves, Plasma Pinch, Synchrotron Radiation},
    Owner                    = {trismegisto},
    Timestamp                = {2015.12.28}
  }

• P. ~P. Kronberg, R. ~V. ~E. Lovelace, G. Lapenta, S. Colgate, and L. Sanna, “Measurement and Simulation of the Electric Current in a kpc-Scale Jet,” in APS Meeting Abstracts, 2012.
  [Bibtex]

  @InProceedings{2012APS..DPPNP8031K,
    Title                    = {Measurement and Simulation of the Electric Current in a kpc-Scale Jet},
    Author                   = {{Kronberg}, P.~P. and {Lovelace}, R.~V.~E. and {Lapenta}, G. and {Colgate}, S. and {Sanna}, L.},
    Booktitle                = {APS Meeting Abstracts},
    Year                     = {2012},
    Month                    = {oct},
    Note                     = {Provided by the SAO/NASA Astrophysics Data System},
    Publisher                = {American Physical Society, 54th Annual Meeting of the APS Division of Plasma Physics},
  
    Abstract                 = {We present radio emission, polarization, and Faraday rotation maps of the radio jet of the galaxy 3C303. From these data we derive the magnetoplasma and electrodynamic parameters of this 50 kpc long jet. For one component of this jet we obtain for the first time a direct determination of a galactic-scale electric current (3 x 1018 A), and its direction-positive away from the active galactic nucleus. Our analysis strongly supports a model where the jet energy flow is mainly electromagnetic.[4pt] P.P. Kronberg, R.V.E. Lovelace, G. Lapenta, S.A. Colgate, Measurement of the Electric Current in a Kpc-Scale Jet, Astrophysical Journal Letters, 741, L15, doi:10.1088/2041-8205/741/1/L15, 2011.},
    File                     = {2012APS--DPPNP8031K.pdf:2012APS--DPPNP8031K.pdf:PDF},
    Owner                    = {trismegisto},
    Timestamp                = {2015.12.28},
    Url                      = {http://adsabs.harvard.edu/abs/2012APS..DPPNP8031K}
  }

You should familiarize also with Birkeland currents. See also this.

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