L. M. Kukin

A new compact microwave spectroradiometer-ozonometer

A new-generation mobile microwave spectroradiometer intended for studying the Earth’s ozone layer is described. The device receives thermal radio-frequency emission of the stratospheric ozone at the frequency of its rotational transition (110 836 MHz) in a 240-MHz frequency band. The spectral resolution at the O3 line center is 1 MHz. The effective noise temperature of the uncooled receiver in the single-sideband mode is ∼2000 K. The ozonometer is equipped with a computer-aided data measurement, calibration, and preprocessing control system. The device is intended to obtain an ozone profile in a 20- to 60-km altitude interval within 15–20 min.

On the behavior of stratospheric ozone in the western Arctic during the 2003–2004 winter and spring

We present the results of simultaneous measurements of variations in the ozone layer in the north-western Arctic conducted with the help of different instruments. It is shown that, in the winter of 2003–2004, when the stratosphere was relatively warm and the wave activity was high, spatial inhomogeneities in the field of ozone distribution were observed. For April 2004, we detect a decrease in the ozone content in the range of heights between 25 and 40 km. This decrease was recorded simultaneously by the HALOE, SAGE, and POAM satellite instruments.

System for measuring collective scattering spectra for thermonuclear plasma diagnostics

The design and arrangement of a detection system for measuring spectra, using a 140 GHz gyrotron as the probe-radiation source, developed for investigating collective Thomson scattering in plasma are discussed. The measurement procedure and examples of the results obtained are presented.

Microwave measurements of the ozone content in winter arctic stratosphere

As a result of the long-term observations lead in region of Kola Peninsula, connection between character of variations of the ozone content in a stratosphere of Arctic regions and behavior and structure of a winter polar vortex is established. During winter seasons with well developed cyclone and duration of stable existence not less than 1.5–2 months were observed extremely low ozone number density at heights 20–25 km connected, apparently, with its chemical destruction. On the other hand, during disturbances of the vortex, accompanied strong stratospheric warming, was registered almost double increase of ozone amount in a high-altitude interval from 20 up to 40 km. Comparison of results of ground-based microwave monitoring of an ozone layer to data of the satellite instrument EOS MLS installed on satellite AURA is lead. In most cases comparison has shown satisfactory within the limits of an error of measurements coincidence of results. However in conditions of atmospheric disturbances when arose significant spatial heterogeneity, the discrepancy of results of comparison was marked. The possible reasons which cause the detected disagreement in results are discussed.

Ground-based microwave spectroradiometer for thermal sounding of the troposphere

The laboratory model of a mobile solid-state uncooled microwave spectroradiometer, operating in the frequency range of 50 to 55 GHz is described. It is designed for remote passive monitoring of the tropospheric temperature. The spectroradiometer consists of a heterodyne receiver with a low noise amplifier at input and 8-channel spectrum analyzer. To ensure the internal calibration of the intensity of the received atmospheric radio emission using the built-in unit type modulator-calibrator based on GaAs diodes with the Schottky barrier. The antenna system of the spectroradiometer consists of a teflon enlightened lens and conical corrugated horn. The device is equipped with an automated control system process measurement, calibration, and data pre-processing.

Improving the Efficiency of Single-Sideband Millimeter-Wave Reception by Returning the Signal Converted into Image

We describe the technique, apparatus, and the results of studies of the possibility of millimeter-wave single-sideband reception with minimum loss, associated with conversion into image. The single-sideband noise temperature of the receivers is improved by a factor of 1.4-1.9 in the N and Y bands.

Automated microwave radiometer for measuring the atmospheric ozone emission line

The work presents the results of upgrading of microwave spectroradiometer for ground-based remote sensing of Earth’s ozone layer improving essentially the noise temperature (up to value less 1500 K). For this, the low-noise high frequency amplifier was set up in front of the receiver and temperature control of the instrument was changed for stable work of the amplifier.

Investigation of MM and Sub-MM Waves Absorption using the Methods of Precise Resonator Spectroscopy

Investigation of continuum absorption (CA) depending on humidity in a mixture of nitrogen and water vapor at the atmospheric pressure has been conducted within 100-210 GHz frequency range at two temperatures: 297 K and 274.5 K using resonator spectrometer. Linear and square humidity parts of the continuum absorption have been separated from the experimental data and values of corresponding parameters have been determined for each temperature. Temperature dependence of the parameters obtained has been estimated. Comparative analysis of the data obtained and results of previous theoretical and experimental studies is presented. The estimation calculations of CA are presented for 269.5 K. The behavior of CA measured is in good agreement with previous measurements and modern conception, but CA temperature dependence is stronger than in previous publications [3-6]. It is concerned with CA properties.

Mixer conversion loss and receiver single-sideband noise temperature improvement by return of signal converted in image

A rather simple and low cost method of improving mixer conversion loss and the single side-band noise temperature of a receiver was proposed and implemented. As a result the single side-band noise temperature of uncooled receivers was reduced to 770 K at a frequency 115.3 GHz and to 1500 K at a frequency 210.5 GHz.

Detection system for the measurements of collective Thomson scattering spectra in fusion plasma

The detection system designed for the proof-of-principle collective Thomson scattering (CTS) experiments using a 140 GHz gyrotron as a source of probing radiation has been discussed. The system is aimed at ion temperature measurements in a moderate size fusion installations W7-AS stellarator (Garching, Germany) and FTU tokamak (Frascati, Italy) as a first step in CTS experiments using gyrotrons with the prospects of its further upgrading for alpha-particle diagnostics. It is capable of ion temperature measurements for a wide range of plasma parameters (H plasma, D plasma, density range from a few times 10/sup 13/ cm/sup -3/ to 2/spl times/10/sup 14/ cm/sup -3/, ion temperatures from few hundred eV to a few keV) in various scattering geometries with the scattering angles from 60/spl deg/ to 180/spl deg/.