LANGMUIR | PROBE
“The Langmuir Probe is by far the best commercial Langmuir Probe on the market, with
ultra fast repeatable measurements. The inclusion of both a Single and Double
Langmuir Probe in each system is evidence of Impedans commitment to its customers.”
LANGMUIR | PROBE
The Langmuir Probe System is one of the most common and
widely used plasma diagnostics and plasma characterisation
instruments for plasma measurement within the bulk of
the plasma.
The Langmuir Spatial Probe uses an automated linear drive to scan across a plasma and
take measurements of plasma parameters at different
locations.
LANGMUIR | PROBE
Plasma Diagnostics MeasuredFloating Potential • Plasma PotentialPlasma Density • Ion Current Density
Electron Energy Distribution Function (EEDF)Electron Temperature
Measurement FunctionalityTime Averaged • Time Resolved • Time Trend
HardwareElectronics and Software
Voltage Scan Range: -150V to +150VCurrent Range: 15nA to 1ATime Resolution: 12.5nS
ProbesLangmuir Double Probe Langmuir Single Probe
Langmuir Spatial Probe with Automated Linear Drive Performing at 0.025 step resolution
300mm as standard (Custom available)Probe Cleaning is Automated and Replaceable
Vacuum FeedthroughAvailable with KF, CF or custom vacuum connectors
LANGMUIR | PROBE
Installation Setup
Generator Match Langmuir ElectronicsPlasma Reactor
Langmuir Probe*
* Langmuir Double Probe or Single Probe
Computer
LANGMUIR | PROBE
How It Works
The probe collects ion and electron current, depending on the polarity of the potential sweep
At very low pressures the ion current to the probe is limited by orbital motion due to the ions
angular momentum
As pressure increases collisions in the sheath reduce the effect of orbital motion
The probe calculates the number of collisions and applies the correct theory
LANGMUIR | PROBE
Typical ResultsCollecting Ions
At large negative bias, electrons are repelled from the probe and ions are collected. A sheath forms around the probe where there are no electrons. Ions are collected
at the edge of the sheath and travel to the probe following at a trajectory which depends on their initial angular momentum. The correct theory for a specific
pressure can be used to predict the ion current at plasma potential which is called the ion saturation
current. From this the ion density can be calculated if we know the electron temperature.
Retarding ElectronsAs the bias approaches the plasma potential, the electrons with high energy are repelled but have
sufficient energy to reach the probe. As we near this point, the electron current increases expotentially. We
can determine the electron temperature from the rate of increase of electron current.
Collecting ElectronsJust at the plasma potential the electron current reaches electron saturation from which value we can determine
the electon density. At potentials above the plasma potential an electron sheath forms and the growth in the
sheath area is seen.
LANGMUIR | PROBE
Applications
The Langmuir plasma measurement system assesses floating potential, plasma density, ion current density, electron energy distribution function,
and electron temperature in the bulk of the plasma.
The Langmuir System can be used in the following applications:Dusty Plasma
Plasma EtchingHiPIMS Plasma
PECVD Space Plasma
Plasma Sputtering
LANGMUIR | PROBE
For further information on the Langmuir System visitimpedans.com/langmuir-probe
To request a quote visitwww.impedans.com/contact
Chase HouseCity Junction Business Park
Northern CrossMalahide Road
Dublin 17Ireland
Ph: +353 1 842 8826Fax: +353 1 891 6519
Web: www.impedans.comEmail: [email protected]
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