Main practical applications of X-rays lie in the important for the society fields of medical imaging, custom, transport inspection and security. Scientific applications besides of fundamental research include material sciences, biomicroscopy, and protein crystallography. Two types of X-ray sources dominate now: conventional tubes and electron accelerators equipped with insertion devices. The first are relatively cheap, robust, and compact but have low brightness and poorly controlled photon spectrum. The second generate low divergent beams with orders of magnitude higher brightness and well-controlled and tunable spectrum, but are very expensive and large in scale. So accelerator based Xray sources are mainly still used for scientific applications and X-ray tubes -in commercial equipment. The latter motivated by the importance for the society made an impressive progress during last decades mostly due to the fast developments of radiation detectors, computers and software used for image acquisition and processing. At the same time many important problems cannot be solved without radical improvement of the parameters of the X -ray beam that in commercial devices is still provided by conventional X -ray tubes.Therefore there is a quest now for a compact and relatively cheap source to generate X-ray beam with parameters and controllability approaching synchrotron radiation. Rapid developments of lasers and particle accelerators resulted in implementation of laser plasma X-ray sources and free electron lasers for various experiments requiring high intensity, shrt duration and monochromatic X-ray radiation. Further progress towards practical application is expected from the combination of laser and particle accelerator in a single unit for effic ient X-ray generation. BASICS AND APPROACHThirty years development of laboratory X-ray lasers allowed to reach ~0.1 keV photon energy of coherent X-ray beams in a repetitive mode. Further scaling shows feasibility of ~0.3 keV coherent radiation in such type of devices. However their average power is still insufficient for many practical applications including medicine and inspection. Much higher power is expected to obtain in future free electron lasers. However according to existing projects their size and cost will prevent wide spreading of this kind of machines. In this project a compact repetitive dichromatic X-ray source (see Fig. 1a) based on novel laser and electron accelerator systems is proposed for medical applications. X-rays originate from Thomson scattering of counter propagating laser and electron beams. Such a "laser-accelerator" approach is very flexible in providing an X-ray beam with properties required by numerous medical applications.As a typical example, requiring a high power X -ray beam, coronary angiography is considered here, which is the leading method of imaging of coronary arteries. More than one million coronary angiography diagnostic procedures per year are applied in the US to evaluate the patient's conditions and choose the best heart treatment s...

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measurements of convective-cell structures in the Proto-Cleo stellarator were not conclusive [6]. In this paper, we compare cross-field and tangential plasma injection in the Proto-Cleo stellarator to demonstrate the role of injection in convective-cell formation. The results show that a significant improvement in confinement occurs with tangential plasma injection.ABSTRACT. Gun injection of plasma parallel to the magnetic field in the Proto-Cleo stellarator results in particle confinement times of 3.5 -4 ms while injection of plasma perpendicular to the magnetic field results in confinement times of 1.5 -2 ms. Calculations of confinement times based on convective-cell theory that includes shear show good agreement with experimentally measured values.