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: info@impedans.com