Authors: Federico Fraternale (Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntville), Nikolai V. Pogorelov (Department of Space Science and Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntville)

The inner and outer heliosheaths (IHS, OHS) offer a unique opportunity to study compressible turbulence in distinct, highly dynamic plasma environments. The solar wind in the IHS is energetically dominated by pickup ions (PUIs) and influenced by the termination shock. The very local interstellar medium (VLISM) in the OHS is strongly affected by the presence of the heliosphere and the heliopause motion.

We present new evidence of time-dependence in MHD-scale turbulence observed by Voyager 1 and 2 (V1, V2) in these regions. We have conducted a time-frequency analysis of fine-scale magnetic field fluctuations and Galactic cosmic ray (GCR) proton and electron count rates, identifying physically relevant coherent, quasi-periodic structures out to 160 AU. We also identify variations over several years in turbulence intensity and intermittency at V1. We explore the potential roles of the solar cycle and charge exchange of neutral solar wind (SW) atoms in the local production of this turbulence.

In the IHS, we examine turbulence using Voyager magnetic field, plasma (PLS), and GCR data. Here, we demonstrate a correlation between turbulence intensity and long-term changes in the thermal plasma quantities measured by Voyager 2. Additionally, turbulence enhancements are identified in the sector region and in proximity to pressure pulses. By conditioning spectral analysis on the angle between the magnetic field and velocity vectors, we estimate turbulence anisotropy in the IHS. Moreover, we show that the power-law behavior of the frequency spectra of the proton and electron GCR rates reflects the influence of turbulence.