Off-axis electron-cyclotron heating in an axisymmetric barrier mirror produces a cylindrical layer with energetic electrons, which flow through the central cell and into the end region. The layer, producing a localized bumped ambipolar potential Phi(C), forms a strong shear of radial electric fields E(r) and peaked vorticity with the direction reversal of E(r)xB sheared flow near the Phi(C) peak. Intermittent vortexlike turbulent structures near the layer are suppressed in the central cell by this actively produced transverse energy-transport barrier; this results in T(e) and T(i) rises surrounded by the layer.

In the framework of current development in 157-nm lithography we have investigated the performance of photodetectors with emphasis to their stability and linearity. The measurements were performed in the radiometry laboratories of the Physikalisch-Technische Bundesanstalt at the Berlin electron-storage rings BESSY I and BESSY II with spectrally dispersed synchrotron radiation as well as with highly pulsed F2 laser radiation at 157 nm in combination with a cryogenic radiometer as the primary detector standard. Relative standard uncertainties of as little as 1% were achieved for the calibration of photodetectors in the spectral range of ultraviolet and vacuum-ultraviolet radiation.

The responsivities as well as the losses of photons through reflection and absorption of a Si photodiode with a SiO, film, and of a GaAs photodiode with a Au film are estimated using an optical model in the wavelength region from 9 to 800 nm. The model is compared with experiments performed in the visible-far ultraviolet region, and good agreements between the calculation and the experiments are obtained except for scale differences due to the surface recombination of carriers. It is shown that the rate of the surface recombination in a Si photodiode can be determined through a measurement of the internal quantum efficiency in the visible-far ultraviolet region. Thus, the spectral responsivities of semiconductor photodiodes in the VUV region can be roughly predicted.

New PIN photodiode devices based on CVD diamond have been produced showing high responsivity in a narrow bandpass around 200 nm. A set of measurement campaigns was carried out to obtain their XUV-to-VIS characterization (responsivity, stability, linearity, homogeneity). The responsivity has been measured from the XUV to the NIR, in the wavelength range of 1 nm to 1127 nm (i.e. 1240 to 1.1 eV). The diamond detectors exhibit a high responsivity of 10 to 30 mA W−1 around 200 nm and demonstrate a visible rejection ratio (200 nm versus 500 nm) of six orders of magnitude. We show that these PIN diamond photodiodes are sensitive sensors in the 200 to 220 nm range, stable under brief irradiation with a good linearity and homogeneity. They will be used for the first time in a solar physics space instrument LYRA, the Large Yield RAdiometer.

Spectral responsivities of photoconductive diamond detectors were measured based on a standard detector calibrated by a rare-gas ionization chamber in the wavelength range from 10to60nm using synchrotron radiation. The photoemission current component was measured separately from the internally generated photocurrent component by using two electrical measurement configurations and by changing the polarity of the applied voltage to the detector. The photoemission current contribution to the total output current was not negligible but dominant in wavelengths longer than 40nm. On the other hand, the internal photocurrent played a major role in wavelengths shorter than approximately 25nm.