Theoretical development of space-born lidar installation based on cw chemical DF-laser onboard for atmospheric monitoring
Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
The first step in the solution of a serious problem of the atmosphere pollution is the study of the nature of its pollution form. Today lidar solves this problem with a high degree of accuracy.
The purpose of this work is the theoretical development of the space based lidar installation main subsystems on the basis of the cw chemical DF-laser (CCDL), operating in pulse-periodic mode.
In the process of lidar installation design, we considered the following: active environment generator (AEG) of CCDL, optical system, photodetector, forming telescope, emission receiving and transmitting channels. We propose master clock—power amplifier structure (MC—PA) as CCDL optical system. DF-CCDL transition to pulse-periodic mode with pulse on-time of 15 ns is performed by clock resonator Q-factor modulation with CdTe electro-optical gate.
As AEG prototype of AEG CCDL AEG Mg-5 developed at NPO «Energomash», enhanced up to the active environment area of 564 cm2, perpendicular to the flux is used. Estimated peak power of emission impulse at the system output was 2,6 MW.
In the course of receiver design, it was suggested to implement the InSb photodetector with effective area of 0.1 m3. The weight of the designed installation with allowance for fuel reserve for operation during 1495 s is 2.76 tons, with occupied volume of 6.49 m3. The weight of the spacecraft with the lidar installation on board equals to 5.73 tons. The carrier rocket Proton-M was used to place the installation into deployment orbit. Evaluation of propane concentration range detected by the developed installation was carried out; and the results are as follows: 472 — 0.21 mg/m3, which exceeds the TLV upper limit more than 1.5 times. The same is for ethane: 434 — 0.036 mg/m3, which exceeds the TLV upper limit more than 1.5 times; methane: 735 — 1.02 mg/m3, which is twice the TLV upper limit. The results show that the developed lidar allows obtaining information even from severely contaminated regions.
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