High resolution X-ray spectroscopy of laboratory sources
A detailed programme of research is presented to design, build and operate a high resolution h?hz5000 curved crystal Johann-type x-ray spectrometer for the waveband below 13A. The spectrometer is used to observe line emission features from different laboratory x-ray sources. Characteristics of the Johann geometry are described with emphasis given to the properties of sensitivity, dispersion, resolving power and waveband. The tolerance of the instrumental parameters is defined for successful high spectral resolution operation. The key feature of the spectrometer is the unique crystal bending device which can generate a high quality cylindrical curvature of radius R=150?5000mm. The crystal focusing alignment and testing procedures are evaluated. Choice of crystals suitable for the observation programme is discussed together with analysis techniques for interpretation of the x-ray spectral line profiles. The instrument is optimised for time-integrated and time-resolved ion temperature measurements of UKAELA DITE Tokamak at the Culham Fusion Laboratory. X-ray line emission results from medium Z He-like and H-like impurity ions are presented for different plasma conditions. Density sensitive He-like and Li-like Aluminium ion satellite emission features are studied for intense transient laser produced plasmas at the Central Laser Facility, SERC Rutherford Appleton Laboratory. The peak plasma electron density of 0.1 time solid density is estimated from these line intensity ratios and is in good agreement with Stark line width measurements. X-ray emission from beam-foil interactions is observed on the Folded Tandem accelerator of the Nuclear Physics Department, Oxford University. The proposed improvement in the intrinsic spectral line broadening due to the accelerator is investigated by high resolution axial beam measurements of the He-like Silicon and H-like Neon n=2 transitions. The Lyman-a intensity ?-ratio and wavelength separation ?hFS is studied for the fine-structure of Hydrogenic Neon, Magnesium, Aluminium and Silicon. The fine-structure separation is compared with the Dirac theory and other experimental data, while the possible mechanisms giving rise to the non-statistical value of the ?-ratio are analysed.