A field programmable gate array unit for the diagnosis and control of neoclassical tearing modes on MAST.

A real-time system has been developed to trigger both the MAST Thomson scattering (TS) system and the plasma control system on the phase and amplitude of neoclassical tearing modes (NTMs), extending the capabilities of the original system. This triggering system determines the phase and amplitude of a given NTM using magnetic coils at different toroidal locations. Real-time processing of the raw magnetic data occurs on a low cost field programmable gate array (FPGA) based unit which permits triggering of the TS lasers on specific amplitudes and phases of NTM evolution. The MAST plasma control system can receive a separate trigger from the FPGA unit that initiates a vertical shift of the MAST magnetic axis. Such shifts have fully removed m∕n = 2∕1 NTMs instabilities on a number of MAST discharges.

Beam emission spectroscopy turbulence imaging system for the MAST spherical tokamak.

A new beam emission spectroscopy turbulence imaging system has recently been installed onto the MAST spherical tokamak. The system utilises a high-throughput, direct coupled imaging optics, and a single large interference filter for collection of the Doppler shifted D(α) emission from the ~2 MW heating beam of ~70 keV injection energy. The collected light is imaged onto a 2D array detector with 8 × 4 avalanche photodiode sensors which is incorporated into a custom camera unit to perform simultaneous 14-bit digitization at 2 MHz of all 32 channels. The array is imaged at the beam to achieve a spatial resolution of ~2 cm in the radial (horizontal) and poloidal (vertical) directions, which is sufficient for detection of the ion-scale plasma turbulence. At the typical photon fluxes of ~10(11) s(-1) the achieved signal-to-noise ratio of ~300 at the 0.5 MHz analogue bandwidth is sufficient for detection of relative density fluctuations at the level of a few 0.1%. The system is to be utilised for the study of the characteristics of the broadband, ion-scale turbulence, in particular its interaction with flow shear, as well as coherent fluctuations due to various types of MHD activity.

A 130 point Nd:YAG Thomson scattering diagnostic on MAST.

A Thomson scattering diagnostic designed to measure both edge and core physics has been implemented on MAST. The system uses eight Nd:YAG lasers, each with a repetition rate of 30 Hz. The relative and absolute timing of the lasers may be set arbitrarily to produce fast bursts of measurements to suit the time evolution of the physics being studied. The scattered light is collected at F/6 by a 100 kg six element lens system with an aperture stop of 290 mm. The collected light is then transferred to 130 polychromators by 130 independent fiber bundles. The data acquisition and processing are based on a distributed computer system of dual core processors embedded in 26 chassis. Each chassis is standalone and performs data acquisition and processing for five polychromators. This system allows data to be available quickly after the MAST shot and has potential for real-time operations.

The MAST motional Stark effect diagnostic.

A motional Stark effect (MSE) diagnostic is now installed and operating routinely on the MAST spherical tokamak, with 35 radial channels, spatial resolution of ∼2.5 cm, and time resolution of ∼1 ms at angular noise levels of ∼0.5°. Conventional (albeit very narrow) interference filters isolate π or σ polarized emission. Avalanche photodiode detectors with digital phase-sensitive detection measure the harmonics of a pair of photoelastic modulators operating at 20 and 23 kHz, and thus the polarization state. The π component is observed to be significantly stronger than σ, in reasonably good agreement with atomic physics calculations, and as a result, almost all channels are now operated on π. Trials with a wide filter that admits the entire Stark pattern (relying on the net polarization of the emission) have demonstrated performance almost as good as the conventional channels. MSE-constrained equilibrium reconstructions can readily be produced between pulses.

Design and implementation of a full profile sub-cm ruby laser based Thomson scattering system for MAST.

A major upgrade to the ruby Thomson scattering (TS) system has been designed and implemented on the Mega-ampere spherical tokamak (MAST). MAST is equipped with two TS systems, a Nd:YAG laser system and a ruby laser system. Apart from common collection optics each system provides independent measurements of the electron temperature and density profile. This paper focuses on the recent upgrades to the ruby TS system. The upgraded ruby TS system measures 512 points across the major radius of the MAST vessel. The ruby laser can deliver one 10 J 40 ns pulse at 1 Hz or two 5 J pulses separated by 100-800 µs. The Thomson scattered light is collected at F/15 over 1.4 m. This system can resolve small (7 mm) structures at 200 points in both the electron temperature and density channels at high optical contrast; ∼50% modulated transfer function. The system is fully automated for each MAST discharge and requires little adjustment. The estimated measurement error for a 7 mm radial point is <4% of T(e) and <3% of n(e) in the range of 40 eV to 2 keV, for a density of n(e)=2×10(19) m(-3). The photon statistics at lower density can be increased by binning in the radial direction as desired. A new intensified CCD camera design allows the ruby TS system to take two snapshots separated with a minimum time of 230 µs. This is exploited to measure two density and temperature profiles or to measure the plasma background light.

Design of a new Nd:YAG Thomson scattering system for MAST.

A new infrared Thomson scattering system has been designed for the MAST tokamak. The system will measure at 120 spatial points with approximately 10 mm resolution across the plasma. Eight 30 Hz 1.6 J Nd:YAG lasers will be combined to produce a sampling rate of 240 Hz. The lasers will follow separate parallel beam paths to the MAST vessel. Scattered light will be collected at approximately f/6 over scattering angles ranging from 80 degrees to 120 degrees. The laser energy and lens size, relative to an existing 1.2 J f/12 system, greatly increases the number of scattered photons collected per unit length of laser beam. This is the third generation of this polychromator to be built and a number of modifications have been made to facilitate mass production and to improve performance. Detected scattered signals will be digitized at a rate of 1 GS/s by 8 bit analog to digital converters (ADCs.) Data may be read out from the ADCs between laser pulses to allow for real-time analysis.

Fast visible imaging of turbulent plasma in TORPEX.

Fast framing cameras constitute an important recent diagnostic development aimed at monitoring light emission from magnetically confined plasmas, and are now commonly used to study turbulence in plasmas. In the TORPEX toroidal device [A. Fasoli et al., Phys. Plasmas 13, 055902 (2006)], low frequency electrostatic fluctuations associated with drift-interchange waves are routinely measured by means of extensive sets of Langmuir probes. A Photron Ultima APX-RS fast framing camera has recently been acquired to complement Langmuir probe measurements, which allows comparing statistical and spectral properties of visible light and electrostatic fluctuations. A direct imaging system has been developed, which allows viewing the light, emitted from microwave-produced plasmas tangentially and perpendicularly to the toroidal direction. The comparison of the probability density function, power spectral density, and autoconditional average of the camera data to those obtained using a multiple head electrostatic probe covering the plasma cross section shows reasonable agreement in the case of perpendicular view and in the plasma region where interchange modes dominate.

[Phasic changes in the brain blood-flow indices of young children in the acute period of complicated pneumonia]. / Fazovost' izmenenii pokazatelei mozgovogo krovotoka u detei rannego vozrasta v ostrom periode oslozhnennoi pnevmonii.

Cerebral hemodynamics has been studied rheoencephalographically in 39 infants early in the course of complicated pneumonia and in 19 healthy controls. The former exhibited phasic changes in cerebral circulation. On the disease day 3 and 10, a significant reduction in the blood flow took place. In children under 6 months of age cerebral circulation is less active than in those over 6 months throughout the whole acute period of complicated pneumonia.

[Rheologic properties of the blood in infants with complicated pneumonia]. / Reologicheskie svoistva krovi u detei rannego vozrasta pri oslozhnennoi pnevmonii.

Blood rheology was assessed in 23 infants with acute pneumonia complicated with respiratory infectious toxicosis during hospitalization to intensive care wards, a control group consisted of 19 healthy infants. Plasma viscosity, red cell deformability, surface architectonics, and aggregation were studied. Patients developed increased plasma viscosity, marked reduction of red cell deformability, and increased aggregation index parallelled by reduced rate of aggregate formation. Changed red cell surface architectonics was associated with a reduced count of discocytes and parallel increase of echinocytes and cupola-like red cell forms. These data evidence marked disorders of blood rheology which should be not disregarded when choosing therapeutic policy.

[Assessment of surface structure of blood cells by phase-contrast and scanning electron microscopy in children]. / Otsenka poverkhnosti arkhitektoniki kletok krovi metodam fazogo-kontrastnoi i skaniruiushchei élektronnoi mikroskopii u detei.

Study of red cell surface structure is a highly informative method for the assessment of the body status in health and disease. The authors have examined the surface red cell structure of infants in health and disease by phase-contrast and scanning electron microscopy and came to the conclusion on the high reliability of the data obtained by phase-contrast microscopy. They recommend this unsophisticated and informative method for clinical practice.

[Diagnosis of disorders of rheological properties of blood and central and cerebral hemodynamics in infants with complicated pneumonia]. / Diagnostika narushenii reologicheskikh svoistv krovi, tsentral'noi i mozgovoi gemodinamiki u detei grudnogo vozrasta s oslozhnennoi pnevmoniei.

A study was made of the rheological blood properties, microcirculation, central and cerebral hemodynamics in children of the first year of life with complicated pneumonia. On admission to the department of intensive care and resuscitation the patients demonstrated pronounced hemorheological and hemodynamic disorders which might in many respects determine the disease gravity. Based on an analysis of the clinical observations and hemodynamic findings 3 periods of complicated pneumonia were distinguished in such children: the critical period, stabilization and repair. Each period is characterized by different compensatory adaptive and non-adaptive erythrocytic and hemodynamic reactions.

[A method of determining erythrocyte deformability]. / Metod opredeleniia deformiruemosti éritrotsitov.

Red cell suspension filtration through synthetic filters is the most prevalent method for estimation of red cell deformability. A modified technique with the use of cellulose acetate filters manufactured by the Polimersintez Research and Production Amalgamation in the town of Vladimir is suggested. Employment of these filters will help introduce this test in clinical practice.

[Accuracy of reproducing images of objects in electro-roentgenographic examination of various organs]. / O tochnosti vosproizvedeniia ob'ektov pri elektrorentgenograficheskom issledovanii nekotorykh organov

Most characteristic distortions of electroroentgenographic and electroroentgenotomographic images obtained with the help of Soviet-made (see article) and (see article) units are reviewed. Images of different nature (positive, negative) are compared. Qualitative and quantitative assessment of distortions is give. An electroentgenographic image is contrasted against an analogous image on a PM-1 film. The dependance of the object's structure discernability on its localization on the electrooentgenographic layer is investigated.

[Characteristics of manifestations of border effect in electroroentgenobronchography]. / Osobennosti proiavleniia kraevogo effekta pri elektrorentgenobronkhografii

Specificity of the image reflecting the outlines of the bronchial lumena on the electroroentgenograms is explained by the manifestation of the border effect. The latter is caused by the non-uniformity of the electric field over the surface of the selenium layer with a regular distribution of charges. With electroroentgenography of sharply contrasted objects in a little contrast medium the potential relief has highly pronounced differences, this leading to distorsion of the dimensions and the shape of the objects under examination. When interpreting electroroentgenograms these specific features should be taken into consideration. In constructing improved medical radiographic equipment it will be advisable to envisage the possibility of controlling the said effect.