Scrape‐off layer width set by non‐linear streamer flows in drift wave turbulence

Abstract

In this work, we discuss the physics behind the excitation of non‐linear streamer flows in drift wave turbulence and how to selectively excite these flows. Streamer flows are modelled as a non‐linear, radially elongated convective cell in drift wave turbulence. It is shown that density modulation is key for exciting streamer flows. We show that streamer flows have a finite frequency, albeit smaller than that of drift waves. Streamers propagate in the ion direction. These theoretical predictions are compared against experimental data, which shows reasonable agreement. Finally, the scrape‐off layer width set by streamer flows is calculated, and a scaling law against macroscopic plasma parameters is obtained.