First results from the modular multi-channel dispersion interferometer at the TEXTOR tokamak.

At the TEXTOR tokamak in Jülich, Germany, a modular dispersion interferometer was installed and operated for the first time. Equipped with four lines of sight, the line-integrated density could be measured in parallel at different major radii with a resolution of better than 3 × 10(17) m(-2). This paper will describe the setup and show the first measurement results. Among others, it was possible to detect the evolution of a disruption with a time resolution of 4 µs. The movement of the runaway beam following the disruption could be resolved spatially and temporarily.

Diagnostics design for steady-state operation of the Wendelstein 7-X stellarator.

The status of the diagnostic developments for the quasistationary operable stellarator Wendelstein 7-X (maximum pulse length of 30 min at 10 MW ECRH heating at 140 GHz) will be reported on. Significant emphasis is being given to the issue of ECRH stray radiation shielding of in-vessel diagnostic components, which will be critical at high density operation requiring O2 and OXB heating.

Development of a multichannel dispersion interferometer at TEXTOR.

The design and main characteristics of 14-channel dispersion interferometer for plasma profile measurement and control in TEXTOR tokamak are presented. The diagnostic is engineered on the basis of modular concept, the 10.6 microm CO(2) laser source and all optical and mechanical elements of each module are arranged in a compact housing. A set of mirrors and retroreflectors inside the TEXTOR vacuum vessel provides full coverage of the torus cross section with 12 vertical and two diagonal lines of sight, no rigid frame for vibration isolation is required. Results of testing of the single-channel prototype diagnostic and the pilot module of the multichannel dispersion interferometer are presented.

Bayesian experimental design of a multichannel interferometer for Wendelstein 7-X.

Bayesian experimental design (BED) is a framework for the optimization of diagnostics basing on probability theory. In this work it is applied to the design of a multichannel interferometer at the Wendelstein 7-X stellarator experiment. BED offers the possibility to compare diverse designs quantitatively, which will be shown for beam-line designs resulting from different plasma configurations. The applicability of this method is discussed with respect to its computational effort.

Diagnostic developments for quasicontinuous operation of the Wendelstein 7-X stellarator.

The stellarator Wendelstein 7-X will allow for quasicontinuous operation with the duration only being limited to two 30 min discharges per day, at a continuous heating power of 10 MW electron cyclotron resonance heating (ECRH) at 140 GHz, by the capacity of the cooling water reservoir. This will result in high thermal loads on all plasma facing components of 50-100 kW/m(2) from radiation alone and of up to about 500 kW/m(2) on components additionally exposed to convective loads. In high density scenarios toroidally varying ECRH stray radiation levels of 50-200 kW/m(2) need to be coped with, requiring careful material selection and different shielding and hardening techniques. Furthermore, a gradual buildup of coatings on plasma facing optical components, which without any measures being taken, would lead to high transmission losses already within a few days of long pulse operation (equivalent to about 1 year of operation in pulsed devices like JET or ASDEX-upgrade) and therefore needs to be prevented as much as possible. In addition in situ cleaning as well as absolute calibration techniques need to be developed for all plasma facing optical systems. Here we report about some of our efforts to find, for various types of diagnostics, ways to cope with these adverse effects. Moreover, we give a few examples for individual diagnostic specific issues with respect to quasicontinuous operation, such as the development of a special integrator for the magnetic diagnostics as well as special interferometer types which can cope with unavoidable vibrations and slow path length changes due to, e.g., thermal expansion of the plasma vessel.

Development of a virtual Z(eff) diagnostic for the W7-X stellarator.

For the W7-X stellarator a diagnostic system for measurement of local Z(eff) values from the visible bremsstrahlung continuum is foreseen. The method is based on passive, absolute measurement of the bremsstrahlung intensity along several lines of sight. In order to eliminate the spurious impact of other radiation sources of different spectral intensity distribution than the bremsstrahlung, like the line radiation, it is intended to spectrally resolve the detected radiation, e.g., by use of microspectrometers. The visible bremsstrahlung background can be extracted by making use of the 1/lambda(2) dependence of its intensity (expressed in unit Wm(3) sr nm) in the high temperature plasmas by using Bayesian data analysis techniques. In a second step, the local values of Z(eff) as a function of the effective plasma radius are derived by inversion, using different regularization methods, of the line-integrated bremsstrahlung signals with the knowledge of the magnetic flux surfaces. Inversion of the full model based on statistical methods allows taking into account all conceivable uncertainties accompanying Z(eff) measurement and provides uncertainties of the local Z(eff) values and valuable information on other uncertain parameters of the model. In this paper we show the first steps in developing a virtual Z(eff) diagnostic for W7-X which allows the optimization of the statistical model as well as of the future diagnostic setup.

Plasma levels of androstenedione, epitestosterone, testosterone and oestrogens in cows at parturition.

The concentration of total unconjugated oestrogens in the peripheral plasma of cows increased from 2.00 +/- 0.20 (S.E.M.) ng/ml 7 days before to 3.87 +/- 0.50 ng/ml 1 day before parturition and declined to values below 0.30 ng/ml on day 2 post partum. The concentrations of androstenedione, epitestosterone and testosterone remained approximately constant at 0.90 +/- 0.10, 0.92 +/- 0.08 and 0.40 +/- 0.20 ng/ml respectively during the last week of pregnancy. After parturition the concentration of the three androgens declined rapidly. Similar to data obtained in goats we did not find a marked increase in androgen levels in the peripheral blood of cows before parturition.

[Specific incorporation of labelled tissue homogenates into the homologous organs of the rat (author's transl)]. / Spezifische Einlagerung markierter Gewebshomogenate in die homologen Organe der Ratte

The time course of the incorporation of radioactivity into the liver, kidney, heart, spleen, lung, adrenal glands, and testes following subcutaneous application of L-histidine-2,5-T-labelled homogenates of liver, kidney and heart has been measured in 105 male Sprague-Dawley rats aged 3 months (weight: x = 350 g). The homogenates had been prepared from organs of rats of the same age, sex and weight, each labelled with 400 muCi L-histidine-2,5-T. The maximal incorporation of activity from the homogenates into the organs investigated has been found 24 h after injection. In the kidney, however, an additional peak appeared already 5 h post applicationen. The comparison of the activities of the liver, kidney and heart, taking into account the differences in organ metabolism, revealed a significantly higher incorporation into the homologous than in the non-homologous organs. This specific incorporation appeared 2 h after the injection and could be found until about 24 h. The type of labelling, the method of sample preparation and the time of absorption allowed to conclude that the specific affinity to the homologous organs might have been due to a relatively small amount of short peptides. The functional significance especially for the regeneration of impaired organs has been discussed taking into account earlier results.