NASA- ESPO TC4
Two Columns
Harvard QCLS Instrument Description:
The Harvard QCLS (DUAL and CO2) instrument package contains 2 separate optical assemblies and calibration systems, with a common data system and power supply. The two systems are mounted in a rack, designed for installation in a pallet, and are described separately below:
The Harvard QCL DUAL instrument simultaneously measures CO, CH4, and N2O concentrations in situ using two thermoelectrically cooled pulsed-quantum cascade lasers (QCL) light sources, a multiple pass absorption cell, and two liquid nitrogen-cooled solid-state detectors. These components are mounted on a temperature-stabilized, vibrationally isolated optical bench with heated cover. The sample air is preconditioned using a Nafion drier (to remove water vapor), and is reduced in pressure to 60 mbar using a Teflon diaphragm pump. The trace gas mixing ratios of air flowing through the multiple pass absorption cell are determined by measuring absorption from their infrared transition lines at 4.59 microns for CO and 7.87 microns for CH4 and N2O using molecular line parameters from the HITRAN data base. In-flight calibrations are performed by replacing the air sample with reference gas every 10 minutes, with a low-span and a high-span gas every 20 minutes. A prototype of this instrument was flown on the NOAA P3 in the summer of 2004.
The Harvard QCL CO2 instrument measures CO2 concentrations in situ using a thermoelectrically cooled pulsed-quantum cascade laser (QCL) light source, gas cells, and liquid nitrogen cooled solid-state detectors. These components are stabilized along the detection axis, vibrationally isolated, and housed in a temperature-controlled pressure vessel. Sample air enters a rear-facing inlet, is preconditioned using a Nafion drier (to remove water vapor), then is reduced in pressure to 60 mbar using a Teflon diaphragm pump. A second water trap, using dry ice, reduces the sample air dewpoint to less than -70C prior to detection. The CO2 mixing ratio of air flowing through the sample gas cell is determined by measuring absorption from a single infrared transition line at 4.32 microns relative to a reference gas of known concentration. In-flight calibrations are performed by replacing the air sample with reference gas every 10 minutes, and with a low-span and a high-span gas every 20 minutes. This is a new instrument, and TC4 will be its first flight campaign.
Accuracy: CO 1 ppb; CH4 15 ppb; N2O 2 ppb; CO20.1 ppm
Precision: CO 0.5 ppb; CH4 2 ppb; N2O 0.3 ppb; CO20.05 ppm
Weight: 292 lbs. (includes rack and inlet)
Power: 115VAC / 400Hz, 3 phases, 700W typical, 1800W max.
Response Time: 1 second
ESPO News:
NOVICE: ESPO is supporting the NOVICE instrument development mission out of Ellington Field TX during September '08.
ARCTAS: The ESPO led ARCTAS mission (Spring and Summer, 2008) has completed very successfully. The NASA DC-8, P-3 and B-200 flew a combined total of 55 sorties and 538 flight hours including the California Air Resource Board CARB study from Palmdale, CA and Ames Research Center.
ESPO is looking forward to supporting the DFRC based NASA Global Hawk development and related UAS missions in 2009.
