Te/Ti effects on JET energy confinement properties

Lately the question has been raised if a modification of the energy-confinement scaling law with respect to the electron to ion temperature ratio, Te/Ti, is required. Theoretically, like in e.g. the Weiland model, the confinement is thought to degrade with Te/Ti and studies of the hot-ion (Ti>/Te) mode seems to corroborate this. In this paper, it is shown that due to a number of effects that cancel each other out, the energy confinement time remains constant for Te/Ti>~1. The numerical study relies on a series of JET shots specifically designed to reveal an effect of Te/Ti in the hot-electron (Te>Ti) mode. A distinct effort was made to keep all current scaling-law parameters constant, including the total heating power. The effects that provide the constant confinement times have therefore nothing to do with the global properties of the plasma, but are rather due to variations in the temperature gradients which affects the transport locally.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

First results from recent JET experiments in Hydrogen and Hydrogen-Deuterium plasmas

The hydrogen campaign completed at JET in 2016 has demonstrated isotope ratio control in JET-ILW using gas puffing and pellets for fuelling, Neutral Beam Injection alone or in combination, with D/H spectroscopy as a diagnostic. The plasma properties such as confinement, L-H threshold, density limit depend on the isotope composition. The L-H transition power increases with the hydrogen concentration with a wide plateau in the range 0.2<nH/(nD+nH)<0.8. Energy confinement is significantly lower in hydrogen than in comparable deuterium ELMy H-mode plasmas, suggesting an isotope mass scaling that is stronger than in IPB98(y,2). In L-mode, the isotope dependence of confinement is weaker. The H-mode density limit in hydrogen is up to 35% lower than in heuterium, whilst it is found to be higher in L-mode. The lower ion mass leads to reduced tungsten sputtering in hydrogen plasmas. During the campaign, the nD/(nD+nH) ratio dropped to ~1% in only a few discharges after the last deliberate introduction of deuterium, although it was seen to rise again to ~2% with several seconds of exposure of the divertor tiles to ~10MW of auxiliary heating. Several ICRH scenarios were also tested in hydrogen plasmas

43rd European Physical Society Conference on Plasma Physics

International audienc

Does SARS-CoV-2 Affect the Prostate? A Molecular Analysis from a Case Series of COVID-19 Patients

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) causes COVID-19 that has been spreading worldwide since December 2019. Viral entry into cells requires expression of both angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) on the surface of the host cell. The male reproductive system, including the prostate, was supposed to be a potential target for SARS-CoV-2 since the presence of ACE and TMPRS2 receptors. This paper investigated for the first time the presence of SARS-CoV-2 mRNA in the prostatic tissue of a patient with active infection. In addition, we searched for the virus in the prostate of five patients after their recovery from COVID-19. The SARS-CoV-2 RNA was not detected in any of the prostate tissues tested even during the acute phase of infection. As case series have limitations, causality cannot be excluded and sporadic evidence of prostatic tissue invasion by SARS-CoV-2 may be detectable