Alfv\'en wave experiments with liquid rubidium in a pulsed magnetic field

TL;DR

This study investigates Alfvén wave behavior in liquid rubidium under high pulsed magnetic fields, revealing wave interactions and resonances that support theoretical models of wave transformation in solar magnetic regions.

Contribution

It provides experimental evidence of Alfvén and sound wave interactions in liquid rubidium at high magnetic fields, confirming theoretical predictions of parametric resonance.

Findings

Emergence of a 4 kHz Alfvén wave at 54 T

Observation of wave period doubling due to resonance

Preliminary numerical simulations support experimental results

Abstract

Magnetic fields are key ingredients for heating the solar corona to temperatures of several million Kelvin. A particularly important region with respect to this is the so-called magnetic canopy below the corona, where sound and Alfv\'en waves have roughly the same speed and can, therefore, easily transform into each other. We present the results of an Alfv\'en-wave experiment with liquid rubidium carried out in a pulsed field of up to 63 T. At the critical point of 54 T, where the speeds of Alfv\'en waves and sound coincide, a new 4 kHz signal appears in addition to the externally excited 8 kHz torsional wave. This emergence of an Alfv\'en wave with a doubled period is in agreement with the theoretical predictions of a parametric resonance between the two wave types. We also present preliminary results from numerical simulations of Alfv\'en and magneto-sonic waves using a compressible MHD code.