Simulations of strong radiatively cooled magnetic reconnection for the MARZ campaign on Z

Strong radiative cooling can significantly modify the structure of a reconnection layer, leading to instabilities and rapid radiative collapse. The MARZ (Magnetically Ablated Reconnection on Z) campaign on the Z machine (Sandia National Laboratories) scales up an existing pulsed-power driven reconnection platform from 1 MA to over 20 MA, in order to access this regime of strong radiative cooling. This platform uses two exploding wire arrays driven in parallel, which create streams of magnetized, β∽1 plasma which collide at the mid-plane, generating a current sheet.

    

We present 2D resistive MHD simulations of the MARZ platform using GORGON, which includes realistic cooling curves and separate ion and electron energy equations. In these simulations, a current sheet develops with a Lundquist number ∽800, containing plasmoids generated by the tearing instability. As the drive strength increases, the layer density and the radiative cooling also increase, leading to a rapid loss of thermal energy within the current sheet. This triggers a sudden collapse of the layer, quashing the plasmoids and stalling the reconnection process. We use the XP2 code to post-process these simulations, enabling photometric predictions for synthetic diagnostics at the Z facility.