High light field confinement for Fluorescence Correlation Spectroscopy using a Solid Immersion Lens

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A simple model is proposed in order to evaluate the complex amplitude point spread function (intensity and phase) of a microscope objective. The model is based on the Fresnel diffraction theory and takes also into account the possible optical aberrations. Experimental evaluation of this amplitude point spread function has been carried out by using a holographic set-up and 66 nanometers gold spheres as punctual objects. The measured values are then compared with the theoretical predicted model.

High resolution infrared imaging of thin films and biological systems is one of the most challenging experimental problems in contemporary science and technology. In this work, we have for the first time successfully tested a novel high resolution approach, based on a spectroscopic version of scanning near-field optical microscopy (SNOM). The coupling of the Vanderbilt Free Electron Laser tunable infrared radiation to SNOM apparatus enabled us to clearly reveal different chemical constituents on a growth me

An experimental study of the extraordinary mode (X mode) absorption at the third electron cyclotron harmonic frequency has been performed on the TCV tokamak in plasmas preheated by X mode at the second harmonic. Full single pass absorption of injected X3 power was measured with X2 preheating in co-current drive (CO-ECCD). The measured absorption exceeds that predicted by the linear ray tracing code TORAY-GA by more than a factor of 2 for the CO-ECCD case. Experimental evidence indicates that a large fractio

Long timescale density peaking has been observed in JET plasmas leading to densities exceeding the Greenwald value. These neutral beam heated discharges are characterized by type-I ELMS and good energy confinement. Central density is limited by neoclassical tearing modes or by termination of H-mode preceded by loss of sawteeth. When these limiting factors are avoided (i.e. at intermediate power level and With optimization of gas puffing) quasi-stationary high density plasmas with peaked density profile are

Current profile tailoring by electron cyclotron heating (ECH) and current drive (ECCD) is used to improve central electron energy confinement in the TCV tokamak. Counter-ECCD on axis alone achieves this goal in a transient manner only. A stable scenario is obtained by a two-step sequence of err-axis ECH, which stabilizes magnetohydrodynamics modes, and on-axis counter-ECCD, which generates a flat or inverted current profile. This high-confinement regime, with central temperatures up to 9 keV (at a. normaliz

Alfven eigenmodes (AEs) with intermediate toroidal mode numbers are modelled using the global gyrokinetic PENN code to determine the stability of high performance tokamak discharges in the presence of energetic particles. A large plasma pressure and a weak magnetic shear in the core give rise to radially extended kinetic AEs, which are stabilized by the high shear at the edge of a divertor (X point) configuration. Large values for the safety factor and the ion Larmor radius in reversed shear operation may h

The energy confinement time of TCV Ohmic, L-mode discharges is observed to depend strongly on the plasma shape, improving slightly with elongation and degrading strongly as triangularity is increased from zero to positive values. The thermal conductivity of these plasmas is found to be independent of the shape. This observation, combined with geometrical effects on the temperature gradient and a degradation with increasing input energy flux, can explain the observed variation in the energy confinement time.

Scanning near-field optical microscopy (SNOM) is an optical microscopy whose resolution is not bound to the diffraction limit. It provides chemical information based upon spectral, polarization and/or fluorescence contrast images. Details as small as 20 nm can be recognized. Photophysical and photochemical effects can be studied with SNOM on a similar scale. This article reviews a good deal of the experimental and theoretical work on SNOM in Switzerland.

We tested a new soft-x-ray transmission spectromiscropy technique on the Aladdin storage ring at the Wisconsin Synchrotron Radiation Center. Transmitted x rays were converted with a photocathode into photoelectrons, which were subsequently electron-optically processed by an x-ray secondary electron-emission microscope producing submicron-resolution images. Test images demonstrated the excellent contrast due to the chemical differences between silicon features and a silicon nitride substrate. We also obtaine

High light field confinement for Fluorescence Correlation Spectroscopy using a Solid Immersion Lens

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Point spread function model for microscopic image deconvolution in digital holographic microscopy

Very high resolution near-field chemical imaging using an infrared free electron laser

Full absorption of third harmonic ECH in TCV tokamak plasmas in the presence of second harmonic ECCD

Long timescale density peaking in JET

Long-pulse improved central electron confinement in the TCV tokamak with electron cyclotron heating and current drive

Stability of Alfven eigenmodes in optimized tokamaks

Influence of plasma shape on transport in the TCV Tokamak

Optical microscopy in the nano-world

An electron imaging approach to soft-x-ray transmission spectromicroscopy