Langmuir Probe
Contents
Description of the Experiment
This experiment's purpose is the determination of the capacity of a variable coax cylindrical capacitor. It has two sections, a first with a Polystyrene dielectric, and a second with air, allowing the determination of the relative dielectric constant of Polystyrene.
Ligações
- Video: rtsp://elabmc.ist.utl.pt/langmuir.sdp
- Laboratory: New Experiments in elab1.ist.utl.pt[1]
- Control room: Langmuir Probe
- Level: ****
Experimental Apparatus
The main chamber consists of a pirex cylinder on which a modified Filament Head is placed to function as a Langmuir probe.
The central filament of 0.2mm diameter has been covered with alumina tube leaving only a 1cm tip exposed to the plasma. The two outer filaments are connected to an "of the shelf" RF generator which ionizes the gas and generates the plasma. This is a simple 3.5W generator which outputs a 50kHz AC signal with 1kV amplitude. To improve stability and homogeneity of the electrical field two molybdenum plaques have been attached using low vapour pressure epoxy, to each outer filament.
