Observations of magnetic flux compression in jet impact experiments

• Published in: Astrophysics and space science Vol. 337; no. 2; pp. 593 - 596
• Main Authors: Moser, A. L., Bellan, P. M.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.02.2012; Springer Nature B.V
• Subjects: Astrobiology; Astronomy; Astrophysics; Astrophysics and Astroparticles; Cosmology; Fluctuations; Magnetic fields; Observations and Techniques; Original Article; Physics; Physics and Astronomy; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Astrophysical jets and outflows; Laboratory astrophysics; Magnetic compression; Flux compression; Molecular cloud
• ISSN: 0004-640X; 1572-946X
• DOI: 10.1007/s10509-011-0860-1

The astrophysical jet experiment at Caltech generates a T =2–5 eV, n =10 21 –10 22  m −3 plasma jet using coplanar disk electrodes linked by a poloidal magnetic field. A 100 kA current generates a toroidal magnetic field; the toroidal field pressure inflates the poloidal flux surface, magnetically driving the jet. The jet travels at up to 50 km/s for ∼20–25 cm before colliding with a cloud of initially neutral gas. We study the interaction of the jet and the cloud in analogy to an astrophysical jet impacting a molecular cloud. Diagnostics include magnetic probe arrays, a 12-channel spectroscopic system and a fast camera with optical filters. When a hydrogen plasma jet collides with an argon target cloud, magnetic measurements show the magnetic flux compressing as the plasma jet deforms. As the plasma jet front slows and the plasma piles up, the density of the frozen-in magnetic flux increases.