Posterior fossa tumors in children: Radiological tips & tricks in the age of genomic tumor classification and advance MR technology

International audienc

Particle Flow during Sawtooth Reconnection: Numerical Simulations of Experimental Observations

International audienc

Microwave response of ITER vacuum windows

\u3cp\u3eDiagnostic systems are essential for the development of ITER discharges and to reach the ITER goals. Many of these diagnostics require a line of sight to relay signals from the plasma to the diagnostic, typically located outside the torus hall. Such diagnostics then require vacuum windows that isolate the torus vacuum and, crucially, ensure containment of hazardous substances. While such windows are routine in many fusion experiments, ITER poses new challenges. The vacuum windows are safety important components class 1 that must withstand all ITER loads. As a consequence, in many cases double disk windows are used with modified frequency response as compared to single disk windows. ITER is a long pulse machine with 20 MW microwave heating installed, giving rise to gradual heating of windows due to stray radiation. The particular microwave heating scheme at ITER may also – in case of an erroneous polarization setting – result in a refracted beam with much higher power density. This paper looks at microwave aspects of ITER windows. The microwave response as a function of frequency is calculated for proposed arrangements. From this response the impact on diagnostic performance may be assessed as well as the thermal load on the window itself.\u3c/p\u3

Systematic ultrasound examinations in neonates admitted to NICU: evolution of portal vein thrombosis

International audienc

Loads due to stray microwave radiation in ITER

High-power microwaves generated by gyrotrons will be extensively used in ITER for a variety of purposes such as assisting plasma breakdown, plasma heating, current drive, tearing mode suppression and as a probing beam for the Collective Thomson Scattering diagnostic. In a number of these schemes absorption of the microwaves by the plasma will not be full and in some cases there could be no absorption at all. This may result in a directed beam with a high microwave power flux or – depending on location and plasma conditions – an approximately isotropic microwave power field. The contribution of electron cyclotron emission to these power densities is briefly discussed. Exposure to in-vessel components leads to absorption by metals and ceramics. In this paper microwave power densities are estimated and, following a brief review of absorption, thermal loads on in-vessel components are assessed. The paper is concluded by a discussion of the current approach to control such loads