Coherent High-Frequency Axial Oscillations in a Partially Magnetized Direct Current Magnetron Discharge.

Area of Science:

• Plasma Physics
• Fluid Dynamics

Background:

• Direct current magnetron discharges are complex systems exhibiting various plasma phenomena.
• Understanding high-frequency oscillations is crucial for controlling plasma behavior and applications.

Purpose of the Study:

• To investigate high-frequency oscillations in neon plasma within a direct current magnetron discharge.
• To characterize the emergence of secondary low-frequency fluctuations at higher discharge currents.

Main Methods:

• Observation of high-frequency oscillations (60 MHz) and secondary low-frequency oscillations (5-10 MHz).
• Analysis of total discharge current to infer axial wave propagation.
• Modeling high-frequency oscillations using lower-hybrid wave theory.

Main Results:

• Coherent 60 MHz fluctuations observed at low discharge currents.
• Secondary 5-10 MHz fluctuations and turbulent 60-100 MHz fluctuations appear above a critical current threshold.
• Evidence of axial wave propagation suggested by current oscillations.

Conclusions:

• Lower-hybrid wave theory provides a model for observed high-frequency oscillations.
• Low-frequency modes are likely driven by a turbulence-induced inverse cascade process, consistent with simulations.