Complex interferometry measures spontaneous magnetic fields between lasers and plasmas
Complex interferometry measures spontaneous magnetic fields between lasers and plasmas lead image
Information about the magnetic-field distribution is crucial for understanding the processes associated with the generation of hot electrons in the setting of shock-ignition fusion. However, the measurement of these spontaneous magnetic fields (SMFs) remains difficult. Interferometry holds promise to solve this problem, however, although its theoretical basis has been well established, complex interferometry has not been effectively employed in laser plasma research until recently.
Zaraś-Szydłowska et al. report complex interferometry measurements of the space-time distribution of SMFs and electron density in ablative plasma by copper thick planar targets. Using a unique diagnostic that couples interferometry and polarimetry measurements in one snapshot, the method allowed measurements in a multi-frame regime.
“By using this method we avoid errors caused from spatial and temporal shifts between separated channels as in the case of classical polaro-interferometry,” said author Agnieszka Zaraś-Szydłowska.
Classical polaro-interferometry independently obtains polarimetric and interferometric images. In contrast, complex interferometry obtains information on SMFs directly from a phase-amplitude analysis of an image called a complex interferogram.
“Performing a proper measurement and data treatment is not trivial. The paper describes measurement conditions and detailed process of data analysis that lead to determine spontaneous magnetic field and electron density distributions with high resolution,” said Zaraś-Szydłowska.
The team demonstrated their approach by measuring the electron density and SMF distribution of a laser ablative plasma generated by irradiating copper targets with an iodine laser at an intensity above about 1016 W/cm2 at the Prague Asterix Laser System facility.
Zaraś-Szydłowska said the team will apply the technique at other laser facilities with the hopes of pushing the study of magnetized plasma streams and magnetic-field reconnection further.
Source: “Implementation of amplitude-phase analysis of complex interferograms for measurements of spontaneous magnetic fields in laser generated plasma,” by A. Zaraś-Szydłowska, T. Pisarczyk, T. Chodukowski, Z. Rusiniak, R. Dudzak, J. Dostal, M. Kalal, Iu. Kochetkov, M. Krupka, S. Borodziuk, and P. Pisarczyk, AIP Advances (2020). The article can be accessed at https://doi.org/10.1063/5.0020511 .
