Volume 104, Number 3, November 2013
|Number of page(s)||5|
|Section||Physics of Gases, Plasmas and Electric Discharges|
|Published online||26 November 2013|
Lyman-α radiation of a probe atomic beam to explore the electric field in plasma sheaths
1 UMR 7345 CNRS–Aix-Marseille-Université, campus Saint-Jérôme - case 321, av. esc. Normandie-Niemen, 13397 Marseille cedex 20, France
2 CAMECA SAS - 29 Quai des Grésillons, 92622 Gennevilliers Cedex, France
Received: 21 August 2013
Accepted: 29 October 2013
An innovative way to non-intrusively measure weak electric fields in plasmas is presented. The electric field is produced between two planar plates which can be immersed in a thermionic plasma. An atomic probe beam, obtained from the conversion of ions into H(2s) in a resonant charge exchange cesium vapor cell, is sent between the two plates. Emission of the Lyman-α line is induced by the external electric field. It originates in the Stark mixing of the two and levels that are separated in energy by the so-called Lamb shift. The light is collected in a direction perpendicular to the probe beam. Theory predicts that its intensity is proportional to the square modulus of the electric field below a critical value. With a proper calibration through measurements in vacuum, the amplitude of the electric field is obtained. Creating an electric field within a plasma, Debye shielding is thus clearly observed. Such measurement can also be done in transparent diluted media. The presented method answers to a long-standing challenge in experimental physics.
This paper is dedicated to late Professor R. A. Stern who was the inspirer of this research
PACS: 52.70.Ds – Electric and magnetic measurements / 52.75.Xx – Thermionic and filament-based sources (e.g., Q machines, double- and triple-plasma devices, etc.) / 34.50.Fa – Electronic excitation and ionization of atoms (including beam-foil excitation and ionization)
© EPLA, 2013
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.