Influence of temperature gradients on drift wave turbulence through numerical simulation

In this study, we investigate the influence of temperature gradients on drift wave turbulence (DWT) in a linear device using Hermes-3 (https://github.com/bendudson/hermes-3/), a three-dimensional drift reduced fluid model built on the BOUT++ framework. According to linear theory, the stability of drift waves depends on the ratio of normalized electron temperature gradient to normalized electron density gradient (η_e), where values of η_e below 2/3 stabilize drift waves, while values above 2/3 lead to destabilization [1, 2]. Previous numerical simulations have shown overall agreement with this theory, which aligns with recent experimental findings in LAPD for η_e < 2/3 [3]. Expanding on prior research, the impact of neutrals on DWT is considered by using a fluid neutral model in Hermes-3. This is investigated both with a fixed neutral background and an evolving neutral background. Additionally, simulations with varying temperature gradients are analyzed to explore the role of turbulence spreading.

Acknowledgments:

Work supported by US DOE under DE-SC0007880, US NSF under NSF PHY 2144099 and in part under the auspices of the US DOE by LLNL under Contract DE-AC52-07NA27344.

References:

[1] Horton et al. Physics of Plasmas 11, 5(2004), 2600-2606

[2] Goldston Introduction to Plasma Physics (2020)

[3] Perks et al. Journal of Plasma Physics 88, 4(2022), 905880405