Relativistic or non-relativistic double layers.

A double layer is said to be strong if the potential drop within the layer is greater than the equivalent thermal energy of the plasma's components.

The strength of a double layer is expressed as the ratio of the potential drop in comparison with the plasma's equivalent thermal energy, or in comparison with the rest mass energy of the electrons. An electrostatic potential imbalance may result (Diagram 2, bottom)ĭouble layers may be classified in the following ways: Formation of a double layer requires electrons to move between two adjacent regions (Diagram 1, top) causing a charge separation. An early review of double layers from laboratory experiment and simulations is provided by Torvén. ĭouble layers are conceptually related to the concept of a 'sheath' ( see Debye sheath). The term ‘electrostatic shock’ in the magnetosphere has been applied to electric fields oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much stronger than the parallel electric field, In laser physics, a double layer is sometimes called an ambipolar electric field. Other names for a double layer are electrostatic double layer, electric double layer, plasma double layers. Similarly, a double layer in the auroral region requires some external driver to produce electron acceleration.Įlectrostatic double layers are especially common in current-carrying plasmas, and are very thin (typically tens of Debye lengths), compared to the sizes of the plasmas that contain them. Double layers are claimed to have been observed in the aurora and are invoked in astrophysical applications.

Ions and electrons within the double layer are accelerated, decelerated, or deflected by the electric field, depending on their direction of motion.ĭouble layers can be created in discharge tubes, where sustained energy is provided within the layer for electron acceleration by an external power source. The sheets of charge, which are not necessarily planar, produce localised excursions of electric potential, resulting in a relatively strong electric field between the layers and weaker but more extensive compensating fields outside, which restore the global potential. For other uses, see Double layer.Ī double layer is a structure in a plasma consisting of two parallel layers of opposite electrical charge. This article is about the structure in plasma physics.

Double laser from ledge