| 1. |
- Luda, T., et al.
(författare)
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Validation of IMEP on Alcator C-Mod and JET-ILW ELMy H-mode plasmas
- 2023
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 65:3, s. 034001-
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Tidskriftsartikel (refereegranskat)abstract
- The recently developed integrated model based on engineering parameters (IMEP) (Luda et al 2020 Nucl. Fusion 61 126048; Luda et al 2021 Nucl. Fusion 60 036023), so far validated on ASDEX Upgrade, has been tested on a database of 3 Alcator C-Mod and 55 JET-ILW ELMy (type I) H-mode stationary phases. The empirical pedestal transport model included in IMEP, consisting now of imposing a fixed value of R < & nabla;T-e > /T-e,T-top = -82.5, allows an accurate prediction of the pedestal top temperature (when the pedestal top density is fixed to the experimental measurements) across these three machines with different sizes, when the pedestal is peeling-ballooning (PB) limited. Cases far from the ideal PB boundary, corresponding to high edge Spitzer resistivity, are instead strongly overpredicted by IMEP. A comparison between the predictions of Europed and IMEP for a subset of JET-ILW cases shows that IMEP can more accurately reproduce the experimental pedestal width. This allows IMEP to better capture profile effects on the pedestal stability, and therefore to correctly describe the negative effect of fueling on the pedestal pressure for PB limited cases. A strong correlation between the separatrix density and the fueling rate has been identified for a subset of JET-ILW cases, when taking into account different divertor configurations. Overall, these promising results encourage further developments of integrated models to obtain reliable predictions of pedestal and global confinement using only engineering parameters for present and future machines.
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| 2. |
- Bonanomi, Francesca, et al.
(författare)
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Another X-ray UFO without a momentum-boosted molecular outflow : ALMA CO(1–0) observations of the galaxy pair IRAS 05054+1718
- 2023
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 673
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Tidskriftsartikel (refereegranskat)abstract
- We present Atacama Large Millimetre/submillimetre Array (ALMA) CO(1–0) observations of the nearby infrared luminous (LIRG) galaxy pair IRAS 05054+1718 (also known as CGCG 468-002), as well as a new analysis of X-ray data of this source collected between 2012 and 2021 using the Nuclear Spectroscopic Telescope Array (NuSTAR), Swift, and the XMM-Newton satellites. The western component of the pair, NED01, hosts a Seyfert 1.9 nucleus that is responsible for launching a powerful X-ray ultra-fast outflow (UFO). Our X-ray spectral analysis suggests that the UFO could be variable or multi-component in velocity, ranging from v/c ∼ −0.12 (as seen in Swift) to v/c ∼ −0.23 (as seen in NuSTAR), and constrains its momentum flux to be ṗoutX−ray ∼ (4 ± 2) × 1034 g cm s−2. The ALMA CO(1–0) observations, obtained with an angular resolution of 2.2″, although targeting mainly NED01, also include the eastern component of the pair, NED02, a less-studied LIRG with no clear evidence of an active galactic nucleus (AGN). We study the CO(1–0) kinematics in the two galaxies using the 3D-BAROLO code. In both sources we can model the bulk of the CO(1–0) emission with rotating disks and, after subtracting the best-fit models, we detect compact residual emission at S/N = 15 within ∼3 kpc of the centre. A molecular outflow in NED01, if present, cannot be brighter than such residuals, implying an upper limit on its outflow rate of Ṁoutmol ≲ 19 ± 14 M⊙ yr−1 and on its momentum rate of ṗoutmol ≲ (2.7 ± 2.4) × 1034 g cm s−1. Combined with the revised energetics of the X-ray wind, we derive an upper limit on the momentum rate ratio of ṗoutmol/ṗoutX−ray < 0.67. We discuss these results in the context of the expectations of AGN feedback models, and we propose that the X-ray disk wind in NED01 has not significantly impacted the molecular gas reservoir (yet), and we can constrain its effect to be much smaller than expectations of AGN ‘energy-driven’ feedback models. We also consider and discuss the hypothesis of asymmetries of the molecular disk not properly captured by the 3D-BAROLO code. Our results highlight the challenges in testing the predictions of popular AGN disk-wind feedback theories, even in the presence of good-quality multi-wavelength observations.
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| 3. |
- Perosa, G., et al.
(författare)
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Femtosecond Polarization Shaping of Free-Electron Laser Pulses
- 2023
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Ingår i: Physical Review Letters. - 0031-9007. ; 131:4
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the generation of extreme-ultraviolet (XUV) free-electron laser (FEL) pulses with timedependent polarization. To achieve polarization modulation on a femtosecond timescale, we combine two mutually delayed counterrotating circularly polarized subpulses from two cross-polarized undulators. The polarization profile of the pulses is probed by angle-resolved photoemission and above-threshold ionization of helium; the results agree with solutions of the time-dependent Schrodinger equation. The stability limit of the scheme is mainly set by electron-beam energy fluctuations, however, at a level that will not compromise experiments in the XUV. Our results demonstrate the potential to improve the resolution and element selectivity of methods based on polarization shaping and may lead to the development of new coherent control schemes for probing and manipulating core electrons in matter.
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