In this work, we describe the design and synthesis of novel isomeric (para- and meta-) core-fluorinated polybenzoxazines from bis(benzoxazine)-containing monomers with 1,4-tetrafluorobenzene or ...4,4′-octafluorobiphenylene dioxyphenylene central units. The new core-fluorinated polybenzoxazines were prepared as dimensionally stable free-standing films without loss of any useful properties. Thermal polymerization of benzoxazine monomers was analyzed using differential scanning calorimetry technique. Peculiarities of the polymerization behavior as well as thermal characteristics of the synthesized fluorinated polybenzoxazines could be related to the position of oxazine ring in the benzoxazine monomer. Furthermore, the effect of the electronic character of the groups surrounding the oxazine ring on the ring-opening polymerization process has been studied. We show correlation between isomeric structure of the fluorinated polybenzoxazines and their physical properties. The resulting polymer films possess a set excellent characteristics including high thermal stability (up to 491 °C), hydrophobicity (water contact angles above 90°), moisture resistance (water uptake less than 1% under water environment for one week), low dielectric constants and loss factors (2.35–2.61 and 0.0071 to 0.0248 at 105 Hz, respectively). This makes the synthesized polymer resins attractive for microelectronics and many other emerging applications.
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•FPBO polymers containing flexible ether linkages, isomeric fragments and core-fluorinated units were developed.•The obtained polymers exhibit excellent properties including high thermal stability, hydrophobicity, and moisture resistance.•Influence of isomerism and the type of core-fluorinated blocks on properties of FPBOs was explored.
•An unusual sequence of power laws in approach to magnetic saturation was observed;•Spontaneous magnetization and exchange stiffness of amorphous alloys were measured;•The local anisotropy constant ...and the structural correlation length were estimated.
Understanding the magnetic correlations in amorphous alloys is the key to enhancing their high soft magnetic properties. The magnetization correlations were studied in amorphous alloy ribbons Fe-Cu-Nb-Si-B by analysis of approach to magnetic saturation within the random magnetic anisotropy model. An unusual sequence of power laws during approach of the magnetization to saturation was observed. This may indicate the transition from isotropic to anisotropic magnetic correlations as the applied field decreases.
Thomson scattering of the core edge and divertor plasma regions of a tokamak with reactor technologies is discussed. The rationale and choice of technical solutions are given, the composition of the ...Thomson scattering diagnostic complex is discussed, as well as an estimate of the accuracy of measuring both electron temperature and density. Particular attention is paid to ensuring the functionality of the proposed diagnostics in the reactor mode of the tokamak operation and the results of testing diagnostic equipment in the experiments on Globus-M2 tokamak.
The results of measuring the electron temperature and density spatial distributions in plasma of the Globus-M2 tokamak using the Thomson scattering diagnostics are presented. The diagnostics provides ...measurements throughout the entire tokamak discharge, starting from time of gas breakdown. The Thomson scattering data were analyzed in order to determine the positions of the last closed flux surface, the plasma magnetic axis, and the radius of inversion during the saw-tooth oscillations. The results of measurements performed during the internal reconnection of magnetic field lines are presents, as well as the dynamics of spatial distributions of electron temperature, density and pressure during the plasma transition to the H-mode. The results of measuring the electron temperature distribution in the scrape-off layer using the Thomson scattering diagnostics are also presented for distances up to 4 cm outside the last closed flux surface.
It is shown that the radial profile of the electron temperature in the Globus-M2 spherical tokamak is related to the radial profile of the electron density by a power law
. An analytical model of the ...density attractor, assuming the dependence of
on the specific poloidal volume
v
, previously tested on the TCV and JET tokamaks with a large aspect ratio, holds on the spherical tokamak, and the approximation of 162 experimental profiles has resulted in
. The proposed model makes it possible to calculate the spatial distribution
and
according to a known magnetic configuration.
The fully consolidated bilayer (consisting of two amorphous Al86Ni9Gd5 melt-spun ribbons) disks with a diameter of 5 mm were produced using unconstrained high pressure torsion (HPT) processing ...subjecting for 2–5 turns at applied pressures of 2 and 4 GPa. The structure and mechanical properties of the disks as well as those of the as-prepared and heated up to 479 K ribbon samples were studied by X-ray diffraction analysis, transmission and scanning electron microscopy, three-point bending tests and measurements of microhardness. It was established that the heat treatment and consolidation resulted in formation of nanocomposite structures consisting of Al nanocrystals 21 and 6 nm in size, respectively, with enhanced microhardness. It was shown that the heat treatment of the ribbon led to a loss of the plastic strain (from 2 to 0.4%) while the consolidated disks retained the same level of plasticity as that in the as-cast amorphous ribbon. The possible reason of the enhanced plasticity of the nanophase composites obtained by deformation-induced crystallization was discussed.
The diagnostic complex of the Globus-M2 spherical tokamak (
R
= 36 cm,
a
= 24 cm), the only operating tokamak in Russia with a divertor plasma configuration, which operates in the range of ...subthermonuclear temperatures (
T
e
to 1.6 keV,
T
i
to 4.5 keV) and densities (
n
e
to 2 × 10
20
m
–3
), is described. The Globus‑M2 tokamak is the unique scientific facility, which is a part of the Federal Center for Collective Use of the Ioffe Institute, Russian Academy of Sciences “Materials Science and Diagnostics in Advanced Technologies.” This allows third parties to perform their research using it. The work contains a list of all diagnostics currently available on the tokamak. The description of the diagnostics is structured in such a way that the reader gets an idea of their capabilities for measuring plasma parameters with an emphasis on the limits and accuracy of the measured values, and also spatial and time resolution. At the same time, many technical details are omitted in order to save space; references are given to papers with a more detailed description of individual diagnostics.
Divertor Thomson Scattering on Globus-M2 Ermakov, N. V.; Zhiltsov, N. S.; Kurskiev, G. S. ...
Plasma physics reports,
12/2023, Letnik:
49, Številka:
12
Journal Article
Recenzirano
We present the first Thomson scattering (TS) measurements of electron temperature in the lower divertor of the Globus-M2 tokamak. The divertor TS diagnostics is designed for local measurements of the
...T
e
(
z
,
t
) in the range of 1–100 eV and
n
e
(
z
,
t
) in the range of
m
–3
. Parameters of the probing Nd:YAG laser are as follows 1064 nm/2 J/100 Hz/3 ns. The probing chord is launched vertically at
R
= 24 cm and covers areas of the inner leg, vicinity of separatrix and private flux region. Along probing chord of 110 mm, 9 spatial points were realized. Advanced filter polychromators were used to analyze Thomson scattering spectra.
NBI-assisted plasma heating with one or two injectors of fast neutral atoms was studied at the Globus-M2 spherical tokamak at the toroidal magnetic fields of 0.8–0.9 T and plasma currents of 0.35–0.4 ...MA. Measurements of the spatial temperature and electron density distributions, performed using the Thomson scattering diagnostics, showed a twofold increase in heating of plasma electrons during the injection of neutral particles with energies of up to 45 keV at the beam power of 0.75 MW, as compared to the ohmic heating regime. Switching on the second additional beam with the particle energy of up to 30 keV and power of up to 0.5 MW resulted in obtaining the hot ion mode in the range of mean plasma densities of (1.6–10) × 10
19
m
−3
. According to the data of active spectroscopy and neutral particle analyzer diagnostics, in the hot zone, the ion temperature reached 4 keV at the plasma density of 8 × 10
19
m
−3
, which is more than 2.5 times higher than the electron temperature.