Effect of toroidal field ripple on plasma rotation in JET

Dedicated experiments on TF ripple effects on the performance of tokamak plasmas have been carried out at JET. The TF ripple was found to have a profound effect on the plasma rotation. The central Mach number, M, defined as the ratio of the rotation velocity and the thermal velocity, was found to drop as a function of TF ripple amplitude (3) from an average value of M = 0.40-0.55 for operations at the standard JET ripple of 6 = 0.08% to M = 0.25-0.40 for 6 = 0.5% and M = 0.1-0.3 for delta = 1%. TF ripple effects should be considered when estimating the plasma rotation in ITER. With standard co-current injection of neutral beam injection (NBI), plasmas were found to rotate in the co-current direction. However, for higher TF ripple amplitudes (delta similar to 1%) an area of counter rotation developed at the edge of the plasma, while the core kept its co-rotation. The edge counter rotation was found to depend, besides on the TF ripple amplitude, on the edge temperature. The observed reduction of toroidal plasma rotation with increasing TF ripple could partly be explained by TF ripple induced losses of energetic ions, injected by NBI. However, the calculated torque due to these losses was insufficient to explain the observed counter rotation and its scaling with edge parameters. It is suggested that additional TF ripple induced losses of thermal ions contribute to this effect

Orbital medial wall fractures: Purely endoscopic endonasal repair with polyethylene implants

Our technique couples the stronger support granted by non-resorbable materials and the minimal invasiveness of the endoscopic approach without the need for long-term nasal packing

Risk perception and media in shaping protective behaviors: insights from the early phase of COVID-19 Italian outbreak

In the absence of target treatments or vaccination, the SARS-CoV-2 pandemic can be impeded by effectively implementing containment measures and behaviors. This relies on individuals’ adoption of protective behaviors, their perceived risk, and the use and trust of information sources. During a health emergency, receiving timely and accurate information enables individuals to take appropriate actions to protect themselves, shaping their risk perception. Italy was the first western country plagued by COVID-19 and one of the most affected in the early phase. During this period, we surveyed 2,223 Italians before the national lockdown. A quarter of the sample perceived COVID-19 less threatening than flu and would not vaccinate, if a vaccine was available. Besides, most people perceived containment measures, based on social distancing or wearing masks, not useful. This perceived utility was related to COVID-19 threat perception and efficacy beliefs. All these measures were associated with the use of media and their truthfulness: participants declared to mainly use the Internet, while health organizations’ websites were the most trusted. Although social networks were frequently used, they were rated lower for trustfulness. Our data differ from those obtained in other community samples, suggesting the relevance to explore changes across different countries and during the different phases of the pandemic. Understanding these phenomena, and how people access the media, may contribute to improve the efficacy of containment measures, tailoring specific policies and health communications

The ITER EC H&CD upper launcher: Seismic analysis

The electron cyclotron heating and current drive (EC H&CD) upper launcher (UL) is a component of the ITER tokamak machine devoted to inject localized high microwave power, in order to counteract plasma instabilities (MHD activity). The UL consists of an assembly of ex-vessel waveguides (with diamond windows and isolation valves) and an in-vessel port plug (PP). The PP, with length close to 6 m, is fixed by a support flange into the upper port of the vacuum vessel (VV) as a cantilevered structure and the nominal gap between PP and port is 25 mm only. During an earthquake, accelerations generated by seismic events cause oscillations of the PP which might be amplified in case of resonance with the natural frequencies. A seismic analysis is therefore required in order to check the response of the UL PP to earthquakes. This paper shows the procedure used for the seismic analysis of the UL PP and results are given in terms of displacements and stresses. The ITER reference earthquake named SL-2 seismic event was considered. The response spectrum method was used in the analysis and floor response spectra (plots of acceleration versus frequency) provided by ITER/F4E at the upper level of the tokamak were applied to the supports as load. A seismic analysis of the UL PP integrated in the upper port is also here reported. The natural frequencies of the PP are far from the frequencies of the peaks in the applied spectra, so no resonance condition occurs. The obtained displacements and stresses of the PP are relatively small. The maximum total displacement is lower than 2 mm and the maximum equivalent stress is below 30 MPa. Since the highest excitation is the vertical one, most part of the total displacement is in the vertical direction. Afterwards, these results due to the seismic loads must be combined with displacements and stresses due to other loads affecting the PP such as the electromagnetic loads