Observation of energetic protons trapped in laboratory magnetic-tower jets

Abstract

Preliminary results of the self-emission of charged particles from magnetically driven plasma jets has been investigated. The jets were launched and driven by a toroidal magnetic field generated by introducing a ∼1.4 MA, 250 ns electrical current pulse from the MAGPIE generator into a radial wire array. This configuration has shown to reproduce some aspects of the astrophysical magnetic-tower jet launching model, in which a jet is collimated by a toroidal magnetic field inside a magnetic cavity. The emission of ions and protons from the plasma was recorded onto Columbia Resin 39 plates using timeintegrated pinhole cameras. In addition a fly-eye camera, an array of 25-496 cylindrical apertures allowed estimating the location of the ion emitting source. The results show the ion emission comes from both the jet and its surrounding magnetic cavity, with the emission extending to a height of at least ∼9 cm from the initial position of the wires. The emission of ions is consistent with the

Nonthermal ion acceleration by the kink instability in nonrelativistic jets

“…There is a significant experimental effort to study the MHD stability of plasma jets in the laboratory in conditions relevant for astrophysical environments 11,[16][17][18][19][20][21] . However, laboratory-produced plasma jets are generally far more collisional than those naturally occurring in space or astrophysical settings.…”

“…These include the flaring activity and energetic particle generation in jets emanating from the solar atmosphere [2][3][4] , the synchrotron emission from bright knots and cosmic ray acceleration in jets from active galaxies [5][6][7] , among others. These instabilities are also associated with violent disruptions and particle acceleration in laboratory fusion devices, such as Tokamaks 8 and Z-pinches [9][10][11] . Yet, the detailed physics underlying how the development of such instabilities in jets accelerates particles remains poorly understood.…”

“…In addition, we explore how the plasma collisionality impacts particle acceleration, which is relevant for a variety of laboratory experiments. Previous experiments using plasma guns 16,17 , modified plasma Z-pinch platforms 11,[18][19][20] and high-power lasers 21 have successfully studied MHD instabilities in jets. In some cases, the observation of nonthermal ions has been reported 11 , yet without a clear understanding of the underlying acceleration mechanism.…”

Characterizing the Plasmas of Dense $Z$ -Pinches

“…A progress in increasing the number of fast deuterons for the neutron production in Z -pinches has been reported by Klir et al [86]. Interestingly, the generation of fast particles was also observed in laboratory astrophysics experiments [91], where protons with energies significantly exceeding the applied voltage were detected in the geometry of magnetic tower jets.…”

Focus on astrophysical jets

“…It is shown that these processes are important candidates to generate magnetic fields in the presence of strong velocity shears, which may naturally originate in energetic matter outbursts of active galactic nuclei and gamma-ray bursters. Suzuki-Vidal et al (2013) show preliminary results of the self-emission of charged particles from magnetically driven plasma jets has been investigated. This configuration has shown to reproduce some aspects of the astrophysical magnetic-tower jet launching model (e.g.…”