The 23rd Academic Exchange Seminar Between Shanghai Jiao Tong University and Osaka University


Takayoshi Sano

(Institute of Laser Engineering, Osaka University)


ABSTRACT

Extreme plasma states observed in astrophysical phenomena can be created in the laboratory using large laser facilities such as the GEKKO laser at Osaka University. For example, the verification of the metallic hydrogen state under ultra-high pressure comparable to that of Jupiter’s interior and the formation of collisionless shocks are being actively pursued. We are conducting laser experiments and MHD simulations on interfacial instabilities in magnetized plasmas associated with supernova explosions. Localized strong magnetic fields have been observed at a shock front of supernova explosions. Experimental confirmation and identification of the physical mechanism for this observation are of great importance in understanding the evolution of the interstellar medium. However, it has been challenging to treat the interaction between hydrodynamic instabilities and an ambient magnetic field in the laboratory. Here, we developed an experimental platform to examine magnetized Richtmyer-Meshkov instability (RMI). The measured growth velocity was consistent with the linear theory, and the magnetic-field amplification was correlated with RMI growth. Our experiment validated the turbulent amplification of magnetic fields associated with the shock-induced interfacial instability in astrophysical conditions. In this talk, I introduce our laser astrophysics experiments and theoretical understandings on the magnetohydrodynamical evolutions of the RMI [1-3].

Reference
[1] T. Sano, Alfven number for the Richtmyer-Meshkov instability in magnetized plasmas, Astrophys. J. 920, 29 (2021)

[2] T. Sano et al., Laser astrophysics experiment on the amplification of magnetic fields by shock-induced interfacial instabilities, Phys. Rev. E 104, 035206 (2021)

[3] T. Sano et al., Suppression of the Richtmyer-Meshkov instability due to a density transition layer at the interface, Phys. Rev. E 102, 013203 (2020)