product overview

LI-7700The methane analyzer is from the United StatesLI-CORCompany Duration4An open circuit methane measurement device launched after years of research and development testing.LI-7700The analyzer is lightweight, low power consumption, high-frequency response, and is used to obtain descriptions of ecosystemsCH₄Necessary for fluxCH₄Density data.
Rice paddies, swamps, wetlands, and other sourcesCH₄The ecosystem generally does not have the conditions to configure scientific research instruments.LI-7700open pathCH₄The analyzer is designed specifically for use in remote field environments.LI-7700Including various innovative designs, it significantly reduces on-site maintenance work, making it possible to collect continuous long-term data from remote sites.
LI-CORThe company has already usedLI-7700The analyzer collected data from various ecosystemsCH₄ Flux data, with a wide range of environmental condition variations--From the tundra of the Arctic Circle to the mangrove forests of the tropics.
LI-7700It is measured in situ using the vorticity covariance methodCH₄The preferred tool for flux.

application area

Methane emissions from ecosystems such as farmland, swamps, wetlands, and forests, as well as monitoring atmospheric methane flux using vorticity covariance methods.

productcharacteristic

LI-7700The open circuit design is atmosphericCH₄Flux measurement provides a first-class solution that meets various ecosystem observation requirements:

→ The system has no air pump and pipeline channels, eliminating pressure drop, water vapor adsorption, and time delay effects, resulting in more accurate measurement results
→ Low system power consumption(～8 W)In the wild, solar panels can be used asLI-7700power supply

→ It can automatically clean the optical path, greatly reducing maintenance work and increasing data security
→ Ultrasonic anemometer signal can be connected to analog input channel
→ High speed data output; Ethernet interface
→Ultra light weight

Technical principles
The LI-7700 analyzer uses a single-mode near-infrared adjustable laser light source for measurement, which can operate at ambient temperature without the need for a low-temperature cooling system, greatly reducing power consumption

Explanation: CH₄The density measurement is based on a single absorption line of the methane absorption spectrum. Utilizing wavelength modulation spectroscopy technology(WMS)Laser wavelength continuous scanning can be performed on specific absorption lines, and the signal is amplified and detected by modulating frequency harmonics. By encoding and detecting signals under high-frequency conditions, the signal-to-noise ratio is greatly improved and the noise level is significantly reduced.

A typical trace gas analyzer needs to achieve andLI-7700quiteCH₄Measurement accuracy requires a few kilometers of optical path length, andLI-7700Only a few tens of meters of optical path is needed. The number of reflections in the optical path is small, and the impact of mirror contamination in the optical path is minimal. useCRDSandICOSWhen waiting for technology, the mirror reflectivity must reach99.99%Or higher.LI-7700In situ under environmental pressureCH₄Density measurement, andCRDSandICOSRelying on a vacuum pump to lower the pressure in the optical path chamber can cause the absorption spectral lines to become sharper.

TECHNICAL INDEX

LI-7700TECHNICAL INDEX

Resolution (RMS noise)	5 ppb @ 10 Hz，2000 ppb CH4
measuring range	0~25 μmol/mol @ -25℃, 0~40 μmol/mol @ 25℃
Data Communication	Ethernet (up to 40 Hz)
measuring principle	Wavelength Modulation Spectroscopy (WMS)
Linearity	<1%; Depends on calibration standards
operating environment	-25~50℃
power supply	10.5~30 V DC
power consumption	8 W (measurement period), 16 W (cleaning period)
Sensor Size	Diameter 14.33 cm, height 82.8 cm
Optical path size	0.5 m physical optical path length, 30 m measurement optical path length
weight	5.2 kg
user interface	Windows®Software, operated through Ethernet