Probing quantum and classical turbulence analogy through global bifurcations in a von K\'arm\'an liquid Helium experiment

We report measurements of the dissipation in the Superfluid Helium high REynold number von Karman flow (SHREK) experiment for different forcing conditions, through a regime of global hysteretic bifurcation. Our macroscopical measurements indicate no noticeable difference between the classical fluid and the superfluid regimes, thereby providing evidence of the same dissipative anomaly and response to asymmetry in fluid and superfluid regime. %In the latter case, A detailed study of the variations of the hysteretic cycle with Reynolds number supports the idea that (i) the stability of the bifurcated states of classical turbulence in this closed flow is partly governed by the dissipative scales and (ii) the normal and the superfluid component at these temperatures (1.6K) are locked down to the dissipative length scale.Comment: 5 pages, 5 figure

MESURE D'AIMANTATION EN CHAMPS MAGNÉTIQUES INTENSES TRANSITOIRES OBTENUS PAR TECHNIQUE « CNARE »

Des champs magnétiques supérieurs à 1 MOe sont obtenus par technique « Cnare ». Les mesures d'aimantation dans les composés magnétiques ordonnés s'effectuent à l'aide de l'effet Faraday ; les problèmes expérimentaux sont discutés. Les résultats obtenus, à température ambiante, sur le Ferrite Grenat de Gadolinium montrent une brusque discontinuité de la rotation Faraday liée au découplage de l'aimantation du sous-réseau terre rare sous l'action du champ extérieur.Magnetic fields up to 1 MOe can be achieved by « Cnare » process. The magnetization measurements in ordered magnetic compounds are performed by the Faraday effect ; the experimental questions are discussed. The results obtained, at room temperature, on the Gadolinium Garnet Ferrite show a sudden discontinuity of the Faraday rotation, which is bound to the reversal of the rare-earth sublattice magnetization under the effect of the magnetic field

Sexual health at 5 years after diagnosis of head and neck cancer

International audiencePurpose: Sexual health (SH) is an emerging concern in the assessment of quality of life in patients surviving head and neck cancer (HNC). Using data from the French National Prospective VICAN Survey, this study aimed to assess SH deterioration five years after HNC diagnosis and related factors.Methods: Using univariate and multivariate analyses were performed in the 241 HNC survivors. We studied the factors associated between the sexuality and intimate life of these patients with demographic and medical data from the national epidemiological survey VICAN 5.Results: Sexuality and body image were altered in 78.8% for men and 79.2% for women. This alteration in sexual quality of life affects both men and women. Dissatisfaction with the frequency of sexual intercourse was associated with being treated with radiotherapy (p=0.024), as well as decrease of sexual desire in patients treated with chemotherapy (p=0.044). Fatigue (p=0.002), impaired physical health (p=0.049), and high disease stage (p=0.001) remained significantly associated, after multivariate analysis, with decreased sexual desire. Among these 3 factors negatively influencing sexual quality of life, two are treatable with appropriate management.Conclusion: Five years after the diagnosis of HNC, a decrease in sexuality and body image are frequent and significantly impact the quality of life of survivors. These observations imply an adaptation of the management of the professionals involved

Cryogenic performances of a heat exchanger prototype suitable for the superconducting HL-LHC recombination dipole D2

In the framework of the future High Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN, most superconducting magnets in the Long Straight Sections will be replaced. Among them, the new D2 recombination dipole will be a He II conduction-cooled magnet with a larger aperture than the LHC dipoles. To provide the required cooling (up to 70 W) to the D2 and to comply with its cryostat integration constraints, a compact heat exchanger was designed by the CEA Département des Systèmes Basses Températures (DSBT) based on a CERN preliminary analysis and a CEA review of the possible cooling schemes. This heat exchanger provides the required heat transfer between the He II pressurized bath and the He II saturated bath to cool the D2 magnet in different operating conditions at 1.8 K and 2 K. The detailed design of the heat exchanger was defined and one prototype was manufactured by industry under the CEA supervision. The heat exchanger prototype is composed of roughly one hundred oxygen-free high purity copper tubes, electron beam welded to the stainless steel He II bath enclosure. The present paper describes the successful cryogenic performance tests of the prototype of the D2 heat exchanger measured in the CEA [email protected] test facility in Grenoble

Assessment of the operation safety margin of the HL-LHC superconducting recombination Dipole D2 in case of helium filling failure

After the successful completion of the cryogenic performance tests of the He II heat exchanger prototype for the D2 recombination dipole of the future HL-LHC project at CERN, specific measurements were performed to determine the operation safety margin in case of abnormal operating conditions. This is particularly relevant in case of the failure of liquid helium supply in the He II cold source. For nominal operation, the liquid level is regulated at a constant value and it is not necessary to know its value very accurately. However, in case of a partial drying of the heat exchanger due to discontinuation of the helium liquid supply, it is essential to monitor the absolute value of the liquid level to anticipate any cooling malfunction. This paper describes the procedure for an accurate in-situ He II level measurement as well as for the heat loss and mass flow rate estimates in a He II phase separator. The operation safety margins of the He II heat exchanger prototype for the D2 magnet are then analyzed for the different operating conditions considered during the HL-LHC runs in case of non-nominal liquid level in the He II cold source

On the investigation of properties of superfluid 4He turbulence using a hot-wire signal

International audienceWe report hot-wire measurements performed in two very different, co-and counter-rotating flows, in normal and superfluid helium at 1.6 K, 2 K, and 2.3 K. As recently reported, the power spectrum of the hot-wire signal in superfluid flows exhibits a significant bump at high frequency [Diribarne et al., Phys. Rev. B 103, 144509 (2021)]. We confirm that the bump frequency does not depend significantly on the temperature and further extend the previous analysis of the velocity dependence of the bump, over more than one decade of velocity. The main result is that the bump frequency depends on the turbulence intensity of the flow, and that using the turbulent Reynolds number rather than the velocity as a control parameter collapses results from both co-and counter-rotating flows. The vortex shedding model previously proposed, in its current form, does not account for this observation. This suggests that the physical origin of the bump is related to the small scale turbulence properties of the flow. We finally propose some qualitative physical mechanism by which the smallest structures of the flow, at intervortex distance, could affect the heat flux of the hot-wire