Debye sheath

The Debye sheath (also electrostatic sheath) is the non-neutral layer several Debye lengths thick where a plasma contacts a material surface.

Related Topics:
Debye length - Plasma

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In a plasma the electrons usually have a temperature on the order of or greater than that of the ions and are much lighter. Consequently they are faster than the ions by at least a factor of 40 (sqrt{m_p/m_e}). At the interface to a material surface, therefore, the electrons will fly out of the plasma, charging the surface negative relative to the bulk plasma. Due to Debye shielding, the scale length of the transition region will be the Debye length lambda_D. As the potential increases, more and more electrons are reflected by the sheath potential. An equilibrium is finally reached when the potential difference is a few times the electron temperature.

Related Topics:
Debye shielding - Debye length

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The Debye sheath is the transition from a plasma to a solid surface. Similar physics is involved in the interface between two regions of disparate plasma parameters. Such an internal transition is known as a double layer.

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