Effect of Partially Screened Nuclei on Fast-Electron Dynamics.

Area of Science:

• Plasma Physics
• Atomic and Molecular Physics
• Astrophysics

Background:

• Fast electrons in plasmas are crucial for understanding various phenomena.
• Previous models often used complete screening approximations, neglecting bound electron effects.
• Partially ionized impurity atoms introduce complex screening effects on charged particle interactions.

Purpose of the Study:

• To analyze fast electron dynamics in plasmas with partially ionized impurity atoms.
• To derive accurate analytical expressions for deflection and slowing-down frequencies.
• To assess the impact of bound electron screening on these frequencies and runaway current evolution.

Main Methods:

• Derivation of analytical expressions for deflection and slowing-down frequencies.
• Inclusion of screening effects from bound electrons in partially ionized impurity atoms.
• Comparison of results with complete screening approximations.

Main Results:

• Analytical expressions for deflection and slowing-down frequencies are derived.
• These frequencies are significantly increased compared to complete screening results, even at subrelativistic energies.
• Modifications to both frequencies are equally important for describing runaway current evolution.

Conclusions:

• Incomplete screening by bound electrons in impurity atoms substantially alters fast electron dynamics.
• Accurate modeling of these effects is critical for understanding and controlling runaway electrons in fusion devices.
• The findings have implications for energy loss in atmospheric discharges and other plasma-based technologies.