185 research outputs found
Helical plasma-wall interaction in the RFX-mod: Effects of high-n mode locking
No full textThe purpose of this paper is to analyse higher toroidal harmonics m = 1 with 7 < n < 23 (secondary modes) in the quasi single helicity, reversed field pinch plasma in the RFX-mod device. The quasi single helicity is an improved confinement state characterized by a dominant mode m/n = 1/7, rotating along the toroidal direction. The spectroscopic measurements in the boundary plasma show footprints of a localized plasma deformation called 'phase locking', which can be described as an interferential pattern of toroidal Fourier harmonics. In the locking region the magnetic field lines are deformed in large poloidal lobes hitting the plasma facing components, a mechanism similar to the 'homoclinic lobes' observed in the Tokamak divertor with RMP application. Correspondingly, the magnetic connection length to the wall presents a strong decrease ('hole') with increased plasma-wall interaction, which fortunately is not stationary, but jumps in the toroidal direction thanks to the effective action of the RFX-mod feedback system. The global plasma wall interaction is the superposition of a rotating helix and of the localized toroidal deformation due to the secondary modes, which mirrors the local emission and particle influx from the wall. The local edge perturbation impacts also on the global plasma performance: a threshold to obtain an electron transport barrier has been identified. An improvement in plasma performance is expected in the upgraded device RFX-mod2, where the magnetic boundary will be modified to decrease the edge field deformation by a factor about 2
Osservazioni stratigrafiche e considerazioni paleoambientali preliminari nell'area di Galliera (Bologna). Una prospettiva di ricerca integrata nei rapporti tra insediamento e paleoambiente nella pianura d'età medievale.
No full textRiassunto - Viene succintamente riletta tutta la documentazione storico-archivistica relativa all’area indagata, evidenziando gli spunti problematici degli aspetti fisico-ambientali in un arco cronologico esteso dall’altomedioevo al XVIII secolo, con l’obiettivo di fornire una taratura ai primi dati stratigrafici originali prodotti. Si provvede ad una prima ricostruzione dell’evoluzione della Rotta Panfilia ricavandone gli ordini di grandezza dei tassi fisiologici di sviluppo e se ne suggeriscono i precedenti. Si propone una preliminare analisi dell’esondabilità pregressa del territorio altomedievale. Si contestualizza l’area geomorfologicamente tentando l’integrazione tra aspetti morfologici e stratigrafici, sottolineando gli argomenti di interesse ed attenzione per una futura analisi geoarcheologica. Si propone il medesimo livello di attenzione analitica per tutte le altre realtà microinsediative medievali note nel territorio ma finora mai sondate. Si suggerisce un termine post quem (1134 d.C.) per l’avulsione inferiore che condusse il fiume medievale nel sottodominio centese.
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Indice – Dati storico documentali (la Torre di Galliera; il centro abitato; lo Scolo Riolo; il Fluvius di Galliera; la Coronella di Galliera; il “Terrazzone”). Inquadramento geomorfologico (la Rotta Panfilia; i dossi di Reno A e B). Una prospettiva ambientale fisica: la taratura paleoidraulica e la paleomorfologia (la sezione dell’alveo di Reno al Gallo). Stratigrafie e contesto locale. Confronti stratigrafici. Conclusioni
Scavi sulla Rocca di Garda (VR)
No full textSintesi delle ricerche archeologiche presso la Rocca di Garda (VR
Slow versus traditional strength training in obese female participants: preliminary results
No full textThe aim of this study was to provide comparative data on a slow versus a traditional supervised resistance training in an obese female population. Forty obese female patients admitted to our rehabilitation hospital were assigned randomly to a slow training group (STgroup; mean age: 47.44 years, mean BMI: 38.53kg/m2) and a traditional training group (TTgroup; mean age: 54.34 years, mean BMI: 39.37kg/m2). The ST protocol included five repetitions for five consecutive bouts on the leg press and extension machine. The duration of each repetition (concentric+eccentricphases)was6sforlegpressand5s for leg extension. The initial load was 50% of the one repetition maximum and then gradually reduced by 20% for each bout. The TT protocol included six consecutive repetitions for five bouts on the leg press and leg extension with 80% of the one repetition maximum load. Both groups performed10sessions.Allofthepatientswereassessedby a visual analogue scale for pain, a Borg scale for subjective fatigue, and an isokinetic strength test. Statistically significant strength improvements were observed in both groups.InSTgroup,statisticallysignificantimprovementsin visual analogue scale scores for knee pain were found at
post, larger than that observed in TTgroup. Subjectively perceived fatigue on the Borgscale decreasedmoreat post in STgroup in comparison with TTgroup. Our preliminary data suggest that ST may represent a preferential strengthening method in obese patients as it can lead to significant strength gains with a relatively lower loading effect on the knee, and hence reduced perception of pain
Particle control systems at the edge of RFP experiments
No full textPlasma performance in reversed field pinch (RFP) devices, as in the tokamak, is strongly affected by neutrals at the edge. So far only a few experiments have been dedicated to an active control of the neutral particle using conventional solutions of axisymmetric magnetic divertors or throat limiters. The alternative `vented pump limiter' concept is more attractive for an RFP experiment due to the edge plasma and confinement properties of this magnetic configuration. In this paper, the application of a vented pump limiter to an RFP is discussed and the prototype module of the vented pump limiter designed for the RFX experiment is presented. Finally, the optimization of this concept for a next step RFP device is presented
Speciminis academici de Helsingforsia, celebri Nylandiae emporio, pars prior, quam, consensu ampl. facult. phil. in Regia Academ. Aboensi, praeside viro cl. mag. Algotho A. Scarin, histor. & philos. civ. prof. Reg: & ord. nec non academiae bibliothecario, publicae ventilatione modestè submittit, Henricus Forsius, Helsingforsia-Nylandus, in audit. superiori, ad d. VIII. Novembr. MDCCLV. h. a. m. s
No full textOsa 2 ilm. 1757, prees. P. KalmInvocatio: D.A.G.Painovuosi nimekkeestä.Dedicatio: Gustavus Samuel Gyllenborg [lat. pr.], Johannes Fortelius [lat. pr.], Petrus Bonsdorff & Joh. Borgström [lat. pr.].Arkit: 3 arkintunnuksetonta lehteä, A-F4 G3
Direct measurement of current filament structures in a magnetic-confinement fusion device
No full textTurbulent structures detected in the edge plasma of fusion devices, often described as blobs, are generally believed to be responsible for confinement degradation. Recent experimental evidence and theories have suggested their filamentary electromagnetic nature. In this Letter the first direct experimental measurements of the parallel current density associated with turbulent structures in a fusion experiment are reported. The electromagnetic nature of structures is clearly shown by identifying the current filaments with a vortexlike velocity pattern and the associated pressure perturbation
Role of radiation re-absorption in the thermal helium beam diagnostic
No full textThe Thermal Helium Beam (THB) is a diagnostic for simultaneously measuring the electron temperature and density profiles of the plasma edge and scrape off layer (SOL). It exploits the line ratio technique of selected He line intensities, emitted by He gas puffed inside the plasma, to locally estimate the plasma properties through a dedicated collisional radiative model (CRM). Standard THB diagnostics used in nuclear fusion devices measure three HeI emission lines: 667.8, 706.5, and 728.1 nm. For the RFP experiment RFX-mod2, a new THB is designed and tested for the first time at the TCV tokamak. It acquires an additional emission line at 501.6 nm, which is exploited to estimate the radiation re-absorption, which is not negligible in regions of large neutral He densities (leading to high re-absorption) and simultaneously low electron density and temperature (lack of other excitation channels). It affects the measurements most strongly at the far SOL, while the significance of re-absorption decreases as it approaches the separatrix. In this paper, plasma density and temperature profiles of the plasma edge at the outboard midplane of TCV, measured with this newly designed THB, are presented. For the first time, the effect of radiation re-absorption on the estimation of electron temperature and density profiles is experimentally measured in a tokamak using the 501 nm line emission intensity. Different CRMs are compared with and without radiation re-absorption, showing good agreement when re-absorption is included and demonstrating how it plays an important role in the far SOL, as expected. (c) 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(https://creativecommons.org/licenses/by/4.0/)
Electron temperature diagnostics in the RFX reversed field pinch experiment
No full textThe paper presents an integrated approach to the problem of electron temperature diagnostics of the plasma in a reversed field pinch. Three different methods, sampling different portions of the electron distribution function, are adopted, namely Thomson scattering, soft X-ray spectroscopy by pulse-height analysis and filtered soft X-ray intensity ratio. A careful analysis of the different sources of systematic errors is performed and a novel statistical approach is adopted to mutually validate the three independent measurements. A satisfactory agreement is obtained over a large range of experimental conditions, indicating that in the plasma core the energy distribution function is well represented by a maxwellian
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