ASDevices > Technologies > 增强型等离子体放电（Epd）

TECHNOLOGY

Enhanced plasma discharge (Epd)

A quantum leap for gas chromatography sensing

The Epd (enhanced plasma discharge) is our proprietary gas detector technology based on a stabilized dielectric barrier discharge (DBD) plasma. The breakthrough resides in the focusing and stabilizing compound electrodes (patent pending) which generate a more stable plasma discharge across a broad range of operating conditions. It uses the highly energetic plasma behaviors to perform measurements. Its versatility and sensitivity make it a technology of choice to measure molecules with high ionization potential, such as the permanent gases, as well as molecules with lower ionization potentials, such as VOCs, hydrocarbons and sulfurs, from ppt to % range.

特点

Replaces DID, PDHID, ECD, FPD, SCD, FID, TCD, mass spectrometer and former PED technologies
Epd technology available in various configurations to suit your application and chromatographic conditions
Unique compound electrode (patent pending) that can withstand high temperature and high pressure
Multiple measurement modes available
ppt to % measurement range
Selective or universal
Compatible with argon, helium, nitrogen, oxygen, hydrogen carrier
Works also at sub-atmospheric pressure

Epd plasma cell

Quartz to metal thermal joint

Allow thermal expansion while maintaining leak integrity
Prevent electrode breakage

Heather mounting hole

Metal body allows uniform heat transfer

Column inlet

Doping inlet or vent

Temperature sensor mounting hole

Optical port 1 and 2

UV treated sapphire
Other materials available

Discharge cell body

Metal body with proprietary coating
Available in ceramic
Withstands high pressure

Compound electrode

Discharge electrode
Stabilisation electrode
Electron injection electrode
Premium quartz shell with proprietary treatment

技术原则

Stabilized dielectric barrier discharge (DBD) 获得专利的

At the core of our Epd technology, a highly energetic plasma source is used to ionize molecules. Its unsurpassed performance is a result of the Epd stabilized dielectric barrier discharge. The DBD isolates the discharge electrodes from the ionized plasma, eliminating sputtering, cell inner wall coating and analyte interference.

Compound electrode 专利申请中

This major breakthrough comes from our innovative compound electrode (patent pending). By nature, DBD generates streamer discharges. This results in a noisy signal impacting the signal-to-noise ratio. The main advantage of our technology is that unlike other DBDs or plasma emission detectors (PEDs), our stabilization and electron injection electrodes (patent pending) are embedded in the compound electrode. This enables the electrode to improve stability by sweeping away the accumulation of charges on the inner surface wall.

Our unique compound electrode technology also provides other benefits such as:

High temperature operation
High pressure operation
Adjustable discharge gap
Higher ionization potential and efficiency

Epd controller/driver

Even on its own, our compound electrode is unique. The level of performance achieved by the Epd, however, could not be attained without close control over various parameters that affect discharge power distribution. This is the purpose of the Epd controller/driver.

Force-driven plasma discharge signal improves plasma
stability compared to other plasma sensing technology
Adaptive control of driving voltage and frequency
Stabilization field automatically controlled

Measurement modes

Epd technology uses the various features of plasma to generate a sensing signal. The different modes employ one or more optical measuring devices known as optical wavelength modules (OWMs).

Direct emission:

In this mode, the OWM is configured with an optical filter to measure the emission of a specific molecule or chemical group.

Tracer mode:

In this mode, the OWM is configured with an optical wavelength to monitor the reaction of molecules with a tracer gas. For example, O₂ emission line reduction from the combustion of hydrocarbons with O₂. Alternatively, CO₂ by-product emission may be monitored.

Constant power mode:

This is a basic mode that uses only one optical channel. The reason for this is to maintain a constant emission intensity when an impurity peak is going through the cell. It also allows real-time compensation of the tailing peak and drifting baseline by adjusting the discharge field to reduce the effect of the residual charges in the discharge gap.