The internal structure of toroidal Alfvén eigenmodes (TAEs) excited in ASDEX-Upgrade plasmas with ion cyclotron resonance heating (ICRH) has been measured through a high-resolution multichord soft x-ray diagnostic. The radial profiles of multiple TAEs are compared with predictions of the linear resistive magnetohydrodynamic code CASTOR and the nonperturbative gyrokinetic code LIGKA and reasonably good agreement is found. The evolution of the TAE radial profiles could be followed in time, both across sawteeth in pure ICRH discharges and in discharges with different types of transitions from L-mode to H-mode obtained with a combination of ICRH and neutral beam injection.
We present the technique of laser Rayleigh scattering imaging (LRSI), which has been used for the mapping of inhomogeneities and point defects in sapphire test masses for laser interferometer gravitational wave detectors. We analyse the errors associated with side wall mapping of cylindrical test masses, and present the comparison of two samples which show significant differences. The technique could be used to improve quality control in the manufacture of optical materials.
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