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Total Internal Reflection Absorption Spectroscopy (TIRAS) for the Detection of Solvated Electrons at a Plasma-liquid Interface
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Exact solution for the generalized Bohm criterion in a two-ion-species plasma.
Dongsoo Lee1, Lutfi Oksuz, Noah Hershkowitz
1Department of Engineering Physics, University of Wisconsin at Madison, Madison, Wisconsin 53706, USA.
Physical Review Letters
|November 13, 2007
Summary
The minimum phase velocity of ion acoustic waves (IAWs) at the sheath-presheath boundary is twice the bulk plasma velocity. This finding supports experimental observations of ion species drift velocities.
Area of Science:
- Plasma Physics
- Fluid Dynamics
Background:
- Ion acoustic waves (IAWs) are fundamental to plasma behavior.
- Understanding plasma boundaries, like the sheath-presheath, is crucial for many applications.
- Previous experimental work indicated specific ion drift velocities at plasma boundaries.
Purpose of the Study:
- To theoretically determine the minimum phase velocity of IAWs at the sheath-presheath boundary.
- To provide a theoretical foundation for observed ion drift velocities in weakly collisional plasmas.
Main Methods:
- Analysis of fluid expressions for IAW phase velocities.
- Application of the generalized Bohm criterion.
Main Results:
- The minimum phase velocity of IAWs at the sheath-presheath boundary equals twice the phase velocity in the bulk plasma.
- This condition explains why each ion species exits the plasma at the bulk IAW phase velocity.
Conclusions:
- The generalized Bohm criterion and fluid dynamics govern ion behavior at plasma boundaries.
- The derived velocity relationship offers a robust theoretical explanation for experimental findings in plasma physics.
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