First-Principles Density Limit Scaling in Tokamaks Based on Edge Turbulent Transport and Implications for ITER.

A first-principles scaling law, based on turbulent transport considerations, and a multimachine database of density limit discharges from the ASDEX Upgrade, JET, and TCV tokamaks, show that the increase of the boundary turbulent transport with the plasma collisionality sets the maximum density achievable in tokamaks. This scaling law shows a strong dependence on the heating power, therefore predicting for ITER a significantly larger safety margin than the Greenwald empirical scaling [Greenwald et al., Nucl. Fusion, 28, 2199 (1988)NUFUAU0029-551510.1088/0029-5515/28/12/009] in case of unintentional high-to-low confinement transition.

Subclinical left ventricular dysfunction in childhood-onset systemic lupus erythematosus: a two-dimensional speckle-tracking echocardiographic study.

OBJECTIVES: The main purpose of the study was to investigate left ventricular (LV) subclinical systolic and diastolic dysfunction in childhood-onset systemic lupus erythematosus (c-SLE) patients using two-dimensional speckle-tracking (2DST) echocardiography. We also interrogated possible correlations between impairment of myocardial deformation and the SLE Disease Activity Index 2000 (SLEDAI-2K), as well as the presence of traditional and disease-related cardiovascular risk factors (CRFs). METHOD: A total of 50 asymptomatic patients and 50 controls (age 14.74 vs. 14.82 years, p = 0.83) were evaluated by standard and 2DST echocardiography. RESULTS: Despite a normal ejection fraction (EF), there was reduction in all parameters of LV longitudinal and radial deformation in patients compared to controls: peak longitudinal systolic strain (PLSS) [-20.3 (-11 to -26) vs. -22 (-17.8 to -30.4)%, p < 0.0001], PLSS rate [-1.19 ± 0.21 vs. -1.3 ± 0.25 s(-1), p = 0.0005], longitudinal strain rate in early diastole [1.7 (0.99-2.95) vs. 2 (1.08-3.00) s(-1), p = 0.0034], peak radial systolic strain [33.09 ± 8.6 vs. 44.36 ± 8.72%, p < 0.0001], peak radial systolic strain rate [1.98 ± 0.53 vs. 2.49 ± 0.68 s(-1), p < 0.0001], and radial strain rate in early diastole [-2.31 ± 0.88 vs. -2.75 ± 0.97 s(-1), p = 0.02]. Peak circumferential systolic strain [-23.67 ± 3.46 vs. -24.6 ± 2.86%, p = 0.43] and circumferential strain in early diastole [0.37 ± 0.17 vs. 0.41 ± 0.15, p = 0.27] were similar between patients and controls, although peak circumferential systolic strain rate [-1.5 ± 0.3 vs. -1.6 ± 0.3 s(-1), p = 0.036] was reduced in c-SLE. Further analysis of patients revealed a negative correlation between LV PLSS and SLEDAI-2K (r = -0.52, p < 0.0001), and also between LV PLSS and the number of CRFs per patient (r = -0.32, p = 0.024). CONCLUSIONS: 2DST echocardiography has identified subclinical LV deformation impairment in c-SLE patients. Disease activity and cumulative exposure to CRFs contribute to myocardial compromise.

Preliminary results concerning the simulation of beam profiles from extracted ion current distributions for mini-STRIKE.

The Radio Frequency (RF) negative hydrogen ion source prototype has been chosen for the ITER neutral beam injectors due to its optimal performances and easier maintenance demonstrated at Max-Planck-Institut für Plasmaphysik, Garching in hydrogen and deuterium. One of the key information to better understand the operating behavior of the RF ion sources is the extracted negative ion current density distribution. This distribution-influenced by several factors like source geometry, particle drifts inside the source, cesium distribution, and layout of cesium ovens-is not straightforward to be evaluated. The main outcome of the present contribution is the development of a minimization method to estimate the extracted current distribution using the footprint of the beam recorded with mini-STRIKE (Short-Time Retractable Instrumented Kalorimeter). To accomplish this, a series of four computational models have been set up, where the output of a model is the input of the following one. These models compute the optics of the ion beam, evaluate the distribution of the heat deposited on the mini-STRIKE diagnostic calorimeter, and finally give an estimate of the temperature distribution on the back of mini-STRIKE. Several iterations with different extracted current profiles are necessary to give an estimate of the profile most compatible with the experimental data. A first test of the application of the method to the BAvarian Test Machine for Negative ions beam is given.