Time development of a current-free double-layer

Time development of a current-free double-layer

Upstream ionization instability associated with a current-free double layer.

A low frequency instability has been observed using various electrostatic probes in a low-pressure expanding helicon plasma. The instability is associated with the presence of a current-free double layer (DL). The frequency of the instability increases linearly with the potential drop of the DL, and simultaneous measurements show their coexistence. A theory for an upstream ionization instabilit...

A Note on Free Vibration of a Double-beam System with Nonlinear Elastic Inner Layer

In this note, small amplitude free vibration of a double-beam system in presence of inner layer nonlinearity is investigated. The nonlinearity is due to inner layer material and is not related to large amplitude vibration. At first, frequencies of a double-beam system with linear inner layer are studied and categorized as synchronous and asynchronous frequencies. It is revealed that the inner l...

Measurement of the energy distribution of trapped and free electrons in a current-free double layer

In the high potential plasma, upstream of the double layer, the measured electron energy distribution function EEDF shows a very clear change in slope at energies break corresponding to the double layer potential drop. Electrons with lower energy are Maxwellian with a temperature of 8 eV, whereas those with higher energy have a temperature of 5 eV. The EEDF in the downstream plasma has a temper...

A theory for formation of a low pressure, current-free double layer

A theory is developed for the formation of a low pressure, current-free double layer just inside an upstream dielectric source chamber connected to a larger diameter, downstream metallic expansion chamber. The double layer is described using four groups of charged particle: thermal ions, mono-energetic accelerated ions flowing downstream, accelerated electrons flowing upstream and thermal elect...