| 1. |
- Joffrin, E., et al.
(författare)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 2. |
- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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| 3. |
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| 5. |
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| 7. |
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| 8. |
- Jmerik, V.N., et al.
(författare)
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Optically pumped lasing at 300.4 nm in AlGaN MQW structures grown by plasma-assisted molecular beam epitaxy on c-Al2O3
- 2010
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Ingår i: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE. - : WILEY-V C H VERLAG GMBH. - 1862-6300. ; 207:6, s. 1313-1317
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Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated optically pumped room-temperature pulse lasing at 300.4 nm from an AlGaN-based multiple-quantum-well (MQW) structure grown by plasma-assisted molecular beam epitaxy on a c-sapphire substrate. The lasing was achieved at the threshold peak power of similar to 12 MW/cm(2). The MQW structure involved AlGaN/AlN short-period super-lattices to decrease the threading dislocation densities from 10(11) down to 10(9)-10(10) cm(-2). Studies of time-resolved photoluminescence (TRPL) spectra and cw PL temperature dependences (10-300K) of different MQW structures, as well as numerical calculations of the optical gain and confinement in the laser structure allowed us to conclude about the optimum design of AlGaN-based MQW structures for the lower threshold UV lasing.
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| 9. |
- Ivanov, Alexander V., et al.
(författare)
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Binding of Au3+ from solutions by nickel(II) and cadmium diisopropyl dithiophosphates: MAS P-31 NMR, structure and thermal behavior of the polynuclear complex [Au-2{S2P(O-iso-C3H7)(2)}(2)] (n)
- 2012
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 38:6, s. 430-439
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Tidskriftsartikel (refereegranskat)abstract
- The paper deals with reactions of freshly precipitated diisopropyl dithiophosphate (Dtph) complexes of nickel(II), [Ni{S2P(O-iso-C3H7)(2)}(2)] and cadmium, [Cd-2{S2P(O-iso-C3H7)(2)}(4)], with the [AuCl4](-) in 2M HCl, resulting in gold transition from the solution to the precipitate as polymeric gold(I) diisopropyl dithiophosphate. The reduction of gold(III) to gold(I) noted in both cases is due to oxidation of the relevant part of the Dtph group to bis(O,O'-di-(iso)-propoxythiophosphoryl) disulfide, (iso-C3H7O)(2)P(S)S-S(S)P(O-iso-C3H7)(2). The polynuclear gold(I) complex [Au-2{S2P(O-iso-C3H7)(2)}(2)] (n) (I) was isolated on a preparative scale from the chemisorption system and studied by MAS P-31 NMR and X-ray diffraction. The key structural unit of I is the non-centrosymmetric binuclear molecule [Au-2{S2P(O-iso-C3H7)(2)}(2)] in which the gold atoms are connected by two bridging Dtph groups. The structure contains two types of non-equivalent binuclear molecules related as conformational isomers. Owing to the relatively weak Au-Au contacts, the neighboring binuclear [Au-2{S2P(O-iso-C3H7)(2)}(2)] molecules are involved in an infinite polymeric chain with conformer alternation along the chain. To elucidate the conditions for the recovery of bound gold(I), the precipitates formed in the sorption systems were studied by simultaneous thermal analysis under argon. As the final product, thermolysis gives reduced metallic gold. The ability of dithiophosphate complexes to bind gold from a solution is much lower than that of dithiocarbamate complexes, which is due to oxidation of some Dtph groups to disulfide.
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| 10. |
- Rodina, Tatyana A., et al.
(författare)
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Crystalline O,O’-di-sec-butyl and O,O’-diethyl dithiophosphate platinum(II) complexes : Synthesis, 13C and 31P CP/MAS NMR, single crystal X-ray diffraction studies and thermal behaviour
- 2011
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Ingår i: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 30:13, s. 2210-2217
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Tidskriftsartikel (refereegranskat)abstract
- Crystalline bis(O,O’-di-sec-butyldithiophosphato)platinum(II) was prepared and studied by means of 31P, 13C CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. The unit cell of the platinum(II) compound is comprised of one centrosymmetric mononuclear molecule [Pt{S2P(O-sec-C4H9)2}2], in which the dithiophosphate groups display structural equivalence in both 31P NMR and XRD data. A pair of the dithiophosphate ligands exhibit the same S,S’-bidentate chelating structural function and form two planar four-membered chelate rings, [PtS2P], in this molecule. The planar configuration of the [PtS4] chromophore in structure 1 is governed by the dsp2-hybrid state of platinum(II). The structural states of the dithiophosphate groups in two different samples of complex 1 (one crystallised from ethanol and the other one precipitated from an aqueous solution) are all characterised by almost rhombic 31P chemical shift tensors. The observed essential dispersion of the 31P NMR chemical shift is caused by a coexistence of six optical isomers of molecule 1. The thermal behaviour of this compound was studied by means of simultaneous thermal analysis (a combination of TG and DSC) under an argon atmosphere. The thermal behaviour shows that the mass of 1 is lost in three steps, involving successive thermal decompositions of the organic and inorganic parts of this compound with platinum(II) dithio-meta-phosphate and reduced metallic platinum as the intermediate and the final products, respectively.
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| 11. |
- Ivanov, Alexander, et al.
(författare)
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A fixation mode of gold from solutions using heterogeneous reaction of cadmium dicyclohexyl dithiophosphate with H[AuCl4]. Structural and (13C, 31P) CP/MAS NMR studies and thermal behaviour of crystalline polymeric gold(I) dicyclohexyl dithiophosphate and bis(dicyclohexylthiophosphoryl) disulphide
- 2013
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Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860 .- 1872-8014. ; 1034, s. 152-161
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Tidskriftsartikel (refereegranskat)abstract
- Two novel compounds: polynuclear catena-poly[bis(3-O,O’-di-cyclo-hexyldithiophosphato-S,S,S’)digold(I)] (Au–Au) (1) and crystalline bis(O,O’-di-cyclo-hexylthiophosphoryl)disulphide, (cyclo-C6H11O)2P(S)S–S(S)P(O-cyclo-C6H11) (2) were prepared using heterogeneous reaction between freshly precipitated binuclear cadmium(II) dithiophosphate (Dtph), [Cd2{S2P(O-cyclo-C6H11}4] and H[AuCl4] in 2 M hydrochloric acid. The isolated compounds 1 and 2 (the fixation mode of gold from the solution and the oxidised form of Dtph groups, respectively) have been studied by means of single-crystal X-ray diffraction, 13C and 31P cross-polarisation / magic-angle-spinning (CP/MAS) NMR spectroscopy and simultaneous thermal analysis (STA). Centrosymmetric binuclear molecule of 1, [Au2{S2P(O-cyclo-C6H11)2}2] comprises a pair of -bridging di-cyclo-hexyl Dtph ligands, linking two neighbouring gold atoms, and displays additional intramolecular aurophilic bond Au···Au. At the supramolecular level of structural self-organisation of complex 1, infinite polymeric zigzag chains arise due to pairs of the secondary bonds Au···S between neighbouring binuclear molecules. Centrosymmetric molecule of 2 displays two O,O-di-cyclo-hexythiophosphoryl fragments, which are connected by the chemical bond S(1)–S(1)a, and a planar zigzag array [S=P–S–S–P=S] passing through the central part of the molecule. To characterise additionally the Dtph groups in both compounds 1 and 2, chemical shift anisotropy (CSA) parameters (aniso and) were calculated from spinning sideband manifolds in experimental 31P MAS NMR spectra. The thermal behaviour of complex 1 was studied using simultaneous thermal analysis (a combination of TG and DSC) under an argon atmosphere. The thermal behaviour displays stepwise mass loss, comprising thermal decompositions of the organic and inorganic parts of 1 with gold(I) dithio-meta-phosphate and reduced metallic gold as the intermediate and the final products, respectively.
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| 12. |
- Ivanov, Alexander V., et al.
(författare)
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Structures of polynuclear thallium(I) and copper(II)-thallium(I) complexes with dialkyldithiocarbamates: 13C and 15N CP/MAS NMR, EPR, and X-ray diffraction studies
- 2006
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 32:5, s. 339-349
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Tidskriftsartikel (refereegranskat)abstract
- A comparative study of polynuclear thallium complexes with dialkyldithiocarbamates [Tl2{S2CNR2}2]n (R = CH3, i-C3H7, C4H9, and i-C4H9; R2 = (CH2)6) was performed by solid-state 13C and 15N CP/MAS NMR spectroscopy. The dithiocarbamate groups were found to be structurally equivalent in the complexes studied. An increase in the positive inductive effect of alkyl substituents at the N atom increased 15N chemical shifts as a result of a combination of positive inductive effect of the alkyl substituents and the mesomeric effect of=NC(S)S-groups. The first representative of thallium(I) complexes with a cyclic dithiocarbamate ligand [Tl2{S2CN(CH2)6}2]n was obtained. Its molecular structure was determined from X-ray diffraction data. The β-form of the isotope-substituted complex [63/65CuTl2{S2CN(CH2)6}4] was obtained and examined by EPR spectroscopy. The EPR spectra were modeled at the second order of the perturbation theory. The spin density at the thallium atoms was calculated and its distribution over the AOs of thallium was determined.
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| 13. |
- Ivanov, Alexander V., et al.
(författare)
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Synthesis, structural and multinuclear natural abundance (C-13, P-31, Pt-195) CP/MAS NMR studies of crystalline O,O '-dialkyldithiophosphate platinum(II) complexes
- 2008
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 34:8, s. 584-593
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Tidskriftsartikel (refereegranskat)abstract
- Platinum(II) O,O'-dicyclohexyl dithiophosphate [Pt{S2P(O-cyclo-C6H11)(2)}(2)] (I) and platinum(II) O,O'-diisopropyl dithiophosphate [Pt{S2P(O-iso-C3H7)(2)}(2)] (II) complexes were obtained and studied by solidstate C-13, P-31, and Pt-195 CP/MAS NMR spectroscopy. The dithiophosphate (Dtph) ligands in molecular structure I were found to be coordinated by platinum in S,S'-bidentate fashion to form the planar chromophore [PtS4] (single-crystal X-ray diffraction data). For complex II, a new alpha-form (alpha-II) was obtained and identified by P-31 MAS NMR spectroscopy. The P-31 chemical shift anisotropy delta(aniso) and the asymmetry parameter eta of the P-31 chemical shift tensor were calculated from the whole MAS spectra.
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| 14. |
- Shubina, Tatiana, et al.
(författare)
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Recombination dynamics and lasing in ZnO/ZnMgO single quantum well structures
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:20
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Tidskriftsartikel (refereegranskat)abstract
- We report a time-resolved study of the recombination dynamics in molecular beam epitaxy grown ZnOZnMgO single quantum wells (SQWs) of 1.0-4.5 nm width. The SQWs exhibit different emission properties, depending on both the well width and defect density. Stimulated emission has been achieved at room temperature in a separate confinement double heterostructure having a 3 nm wide SQW as an active region. It has been found that a critical parameter for the lasing is the inhomogeneous broadening of both QW and barrier emission bands. © 2007 American Institute of Physics.
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| 15. |
- Bourguignon, J., et al.
(författare)
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Chiral ditopic receptors. Application to palladium-catalyzed allylic alkylation
- 2003
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 59:48, s. 9583-9589
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Tidskriftsartikel (refereegranskat)abstract
- Chiral pyridinooxazoline, quinolinooxazoline, bis(oxazolino)pyridine (pybox), and bisoxazoline (box) derivatives containing crown ether residues were prepared. Some of the ligands were assessed in substrate binding studies and in palladium catalyzed allylic alkylations.
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| 16. |
- Bredyuk, O. A., et al.
(författare)
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Structural organization of cadmium(II) and copper(II) dithiocarbamate complexes with dialkyl-substituted and cyclic ligands: Synthesis, single-crystal X-ray diffraction, EPR, and CP/MAS13C, 15N, and 113Cd NMR
- 2005
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Ingår i: Russian Journal of Inorganic Chemistry. - 0036-0236 .- 1531-8613. ; 50:11, s. 1710-1726
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Tidskriftsartikel (refereegranskat)abstract
- A comparative study of polynuclear thallium complexes with dialkyldithiocarbamates [Tl2{S2CNR2} 2]n (R = CH3, i-C3H7, C4H9, and i-C4H9; R2 = (CH2)6) was performed by solid-state 13C and 15N CP/MAS NMR spectroscopy. The dithiocarbamate groups were found to be structurally equivalent in the complexes studied. An increase in the positive inductive effect of alkyl substituents at the N atom increased 15N chemical shifts as a result of a combination of positive inductive effect of the alkyl substituents and the mesomeric effect of =NC(S)S-groups. The first representative of thallium(I) complexes with a cyclic dithiocarbamate ligand [Tl2{S2CN(CH2) 6}2]n was obtained. Its molecular structure was determined from X-ray diffraction data. The β-form of the isotope-substituted complex [63/65CuTl2{S 2CN(CH2)6}4] was obtained and examined by EPR spectroscopy. The EPR spectra were modeled at the second order of the perturbation theory. The spin density at the thallium atoms was calculated and its distribution over the AOs of thallium was determined.
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| 17. |
- Ivanov, Alexander V., et al.
(författare)
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Bis(diethyldithiocarbamato)pyridinezinc(II) and -copper(II) clathrates M(Edtc)2Py·nL (L = CH2Cl2 and CHCl3; n = 1 and 0.5) : Molecular and crystal structures and EPR and high-resolution solid-state (13C, 15N) NMR spectra
- 1999
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 25:8, s. 543-555
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Tidskriftsartikel (refereegranskat)abstract
- X-ray diffraction analysis, EPR, and high-resolution solid-state (13C, 15N) NMR spectroscopy were used to examine structural organization and spectral properties of six bis(diethyldithiocarbamato)pyridine-zinc(II) and copper(II) solvates with dichloromethane and chloroform, M(Edtc)2Py·nL (n = 1 and 0.5). Typical of the clathrate-type structures, the compounds are penetrated by the ordered molecular channels filled with chemically nonbonded chlorohydrocarbon molecules. At the molecular level, the geometry of coordination polyhedra of complexing atoms is intermediate between trigonal bipyramidal and square pyramidal (the contribution of the square-pyramidal component is quantitatively estimated for the zinc clathrate). Accordingly, the ground state of the unpaired electron in the copper(II) compounds is a combination of the dx2-y2 and dz2 orbitals. It is shown that the nonequivalence of the Edtc- ligands in zinc(II) clathrates manifests itself both magnetically and structurally. The chlorine atoms of the solvate dichloromethane molecules, unlike chloroform molecules, are disordered over the two structural positions with different multiplicities. The 13C and 15N NMR signals are assigned to the atomic positions in the resolved molecular structures
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| 18. |
- Ivanov, Alexander V., et al.
(författare)
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Bis(dimethyldithiocarbamato)(pyridine)zinc and -copper(II) and Their Benzene Solvates: EPR and Solid-State Natural Abundance (13C, 15N) CP/MAS NMR
- 2002
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 28:1, s. 57-63
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Tidskriftsartikel (refereegranskat)abstract
- Adducts of bis(dimethyldithiocarbamato)zinc and -copper(II) complexes with pyridine, [M(Py)(Mdtc)2], and their benzene solvates [M(Py)(Mdtc)2] · 0.5C6H6 were synthesized. The electron paramagnetic resonance method and solid-state 13C and 15N CP/MAS NMR spectroscopy were used to perform a comparative study of the compounds obtained. The EPR data showed that the geometry of Cu(II) coordination polyhedra both in the adduct itself [Cu(Py)(Mdtc)2], and in its solvate, [Cu(Py)(Mdtc)2] · 0.5C6H6 is intermediate between a square pyramid (SP) and a trigonal bipyramid (TBP), the contribution from the latter being dominant (75%) in [Cu(Py)(Mdtc)2]. In the solvated adduct [Cu(Py)(Mdtc)2] · 0.5C6H6, the copper(II) polyhedron is distorted to form an SP-enriched structure (the contribution from TBP is reduced to 55%). It was found NMR data that [Zn(Py)(Mdtc)2] exists in a single high-symmetry molecular form. Coordinated pyridine molecule shows molecular motion about the Zn-N bond. The solvation of the adduct results in structural nonequivalence of the Mdtc-ligands in [Zn(Py)(Mdtc)2] · 0.5C6H6. Signals in the 15N NMR spectra were assigned to the structural positions of the atoms in the previously described molecular structure of a solvated adduct. It was found that the heterogeneous reaction of adduct formation during the absorption of pyridine from the gas phase by polycrystalline [Zn2(Mdtc)4] species is accompanied by the dissociation of binuclear molecules.
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