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In this paper, we study the stationary boundary value problem derived from the magnetic (non) insulated regime on a plane diode. Our main goal is to prove the existence of non-negative solutions for that nonlinear singular system of second-order ordinary differential equations. To attain such a goal, we reduce the boundary value problem to a singular system of coupled nonlinear Fredholm integral equations, then we analyze its solvability through the existence of fixed points for the related operators. This system of integral equations is studied by means of Leray-Schauder’s topological degree theory.

The paper presents the results of calculation and optimization of a structure of a radial insulating magnetic field in an acceleration gap of a high-power ion diode. A diode configuration with an induction plasma source and an anode configuration with azimuthally symmetrical slots and a pair of cathode coils of a magnetic diode system have been studied. When the size of the slots is ≤5 mm and codirectional magnetic fields of a diode and shock induction coil, the perturbation of the B-field does not exceed ≤20% and is located in the region near the anode. In this condition, the topology of the magnetic field В = f(1/r) is maintained in the acceleration gap. It was shown that the required radial distribution of the B-field can be optimized by varying the anode profile in the region opposite to two cathode coils of the diode magnetic system.

The paper presents the results of the analysis of the influence of curvature of the electrons trajectory in the anode–cathode gap of an ion diode on the diode impedance and evaluation of applicability of the one-dimensional (1D) Child–Langmuir (CL) ratio for calculation of the electron current. Investigations of an ion diode with a graphite anode in self-magnetic insulation mode were carried out. Experiments were performed on the TEMP-4M ion accelerator set in a double pulse mode, with the first negative pulse (150–200 kV, 400–600 ns) followed by the second positive pulse (250–300 kV, 150 ns). The result of this study is that we have determined the boundary conditions for the applicability of 1D CL ratio for calculation of the electron current in the ion diode. It was found that the deviation of the diode current–voltage characteristics from CL ratio will be observed only with a significant change in the acceleration voltage during electron drift or when the electron drift time exceeds the transit time of ions.

The ion B r -diode in which plasma is generated under the action of a negative pre-pulse voltage is presented. Preliminary plasma formation allows the energy released in the diode during a positive voltage pulse to be increased. The high-energy ion beam parameters are investigated for the magnetic field induction changing from 0.8В cr to 1.7B cr .

A magneto-inertial fusion (MIF) approach to inertial confinement fusion (ICF), based on laser-driven magnetic-flux compression (LDFC) is described. This approach benefits from both the high-energy-density characteristic to ICF and the thermal insulation of the fuel by magnetic fields, typical of MFE. The reduction in thermal-conduction losses in the hot spot of an imploding target that has trapped and amplified a pre-seeded magnetic flux leads to increased hot-spot temperatures at lower implosion velocities than required in conventional ICF. This can lead to ignition designs with larger energy gains. This work describes the main concept and the use of a compact magnetic-pulse system to seed a macroscopic magnetic field into cylindrical DD-filled targets, which are radially driven with the OMEGA laser. The compression of the internal magnetic flux is measured with proton deflectometry. Magnetohydrodynamic simulations predict compression of a 0.1-MG seed field to multi-megagauss values, at which levels the radial electron thermal conduction in the hot spot is significantly inhibited. Initial benchmark experiments are described.

A 100 kV ion source test stand formerly operated at Lawrence Livermore National Laboratory has been relocated to Princeton Plasma Physics Laboratory, where it is being installed and prepared for operation. A variety of topics relevant to ion-beam-driven high energy density physics and heavy ion fusion will be explored at this facility. The practicality of magnetic insulation to improve the performance of electrostatic accelerators will be investigated by determining whether a pair of parallel plates forming a high-voltage gap can sustain higher electric field gradients, when an electric current is passed through the electrode at the cathode potential so as to produce a magnetic field, which is everywhere parallel to the surface. The facility will also be used to develop and characterize improved plasma sources for space charge neutralization of intense ion beam systems such as the Neutralized Drift Compression Experiment-II facility. The negative halogen ion beam and ion-ion plasma studies previously initiated when this test facility was located at Lawrence Livermore National Laboratory will be resumed, and other experimental topics are also under consideration.

A condition for the transition of the electron beam produced in a coaxial rod-pinch diode to the mode of magnetic insulation has been established from the law of conservation of particle and field momentum fluxes. The magnetic field of the external current has been shown to contribute twice as much to magnetic insulation of the beam as the magnetic field of the electron beam self-current. Based on the relations derived, a model has been constructed for magnetic insulation of the electron flow in high-current rod-pinch diodes, which are used for radiography of high speed phenomena. The obtained theoretical results agree well with the results of numerical calculations and with experimental data gained at the Naval Research Laboratory (USA).

Los dispositivos de alta energía son diseñados para que funcionen con campos eléctricos y magnéticos extrema-damente altos. Debido a esto, dichos dispositivos presentan fenómenos y comportamientos no lineales, como el aislamiento magnético que altera el transporte de los electrones. La no linealidad ha obligado a analizar y revisar desde el punto de vista matemático las condiciones de frontera y las soluciones del problema. El objetivo de este trabajo es exponer el tema a un nivel que facilite su difusión entre la comunidad académica no familiarizada con el mismo. Para ello, el trabajo presenta una descripción de los fenómenos que se generan cuando hay campos eléctricos y magnéticos muy altos, tomando el caso de un diodo plano al vacío, así como las ecuaciones que modelan el fenómeno de aislamiento magnético; también demuestra la existencia de las soluciones y encuentra las positivas en base a los métodos de solución superior e inferior para problemas de valor de frontera, y pro-porciona algunos ejemplos de aplicación del fenómeno de aislamiento magnético.

HighlightsFe3+, Co2+, H3BTC, and collagen peptide are used to achieve a one-step assembly of stable FeCo-MOG/CP by manipulating the complexation effect and solution polarity.By optimizing pyrolysis, two kinds of nitrogen-doped carbon aerogels loaded with virus-shaped and nanospherical magnetic particles are obtained.FeCo/Fe3O4/NC and FeCo/NC aerogels exhibit excellent electromagnetic wave absorbing and radar stealth performances.Metal–organic gel (MOG) derived composites are promising multi-functional materials due to their alterable composition, identifiable chemical homogeneity, tunable shape, and porous structure. Herein, stable metal–organic hydrogels are prepared by regulating the complexation effect, solution polarity and curing speed. Meanwhile, collagen peptide is used to facilitate the fabrication of a porous aerogel with excellent physical properties as well as the homogeneous dispersion of magnetic particles during calcination. Subsequently, two kinds of heterometallic magnetic coupling systems are obtained through the application of Kirkendall effect. FeCo/nitrogen-doped carbon (NC) aerogel demonstrates an ultra-strong microwave absorption of − 85 dB at an ultra-low loading of 5%. After reducing the time taken by atom shifting, a FeCo/Fe3O4/NC aerogel containing virus-shaped particles is obtained, which achieves an ultra-broad absorption of 7.44 GHz at an ultra-thin thickness of 1.59 mm due to the coupling effect offered by dual-soft-magnetic particles. Furthermore, both aerogels show excellent thermal insulation property, and their outstanding radar stealth performances in J-20 aircraft are confirmed by computer simulation technology. The formation mechanism of MOG is also discussed along with the thermal insulation and electromagnetic wave absorption mechanism of the aerogels, which will enable the development and application of novel and lightweight stealth coatings.

Strong magnetic fields are required in many fields, such as medicine (magnetic resonance imaging), pharmacy (nuclear magnetic resonance), particle accelerators (such as the Large Hadron Collider) and fusion devices (for example, the International Thermonuclear Experimental Reactor, ITER), as well as for other diverse scientific and industrial uses. For almost two decades, 45 tesla has been the highest achievable direct-current (d.c.) magnetic field; however, such a field requires the use of a 31-megawatt, 33.6-tesla resistive magnet inside 11.4-tesla low-temperature superconductor coils 1 , and such high-power resistive magnets are available in only a few facilities worldwide 2 . By contrast, superconducting magnets are widespread owing to their low power requirements. Here we report a high-temperature superconductor coil that generates a magnetic field of 14.4 tesla inside a 31.1-tesla resistive background magnet to obtain a d.c. magnetic field of 45.5 tesla—the highest field achieved so far, to our knowledge. The magnet uses a conductor tape coated with REBCO (REBa 2 Cu 3 O x , where RE = Y, Gd) on a 30-micrometre-thick substrate 3 , making the coil highly compact and capable of operating at the very high winding current density of 1,260 amperes per square millimetre. Operation at such a current density is possible only because the magnet is wound without insulation 4 , which allows rapid and safe quenching from the superconducting to the normal state 5 – 10 . The 45.5-tesla test magnet validates predictions 11 for high-field copper oxide superconductor magnets by achieving a field twice as high as those generated by low-temperature superconducting magnets. A copper oxide high-temperature superconductor magnet generates a direct-current magnetic field of 45.5 tesla—the highest value reported so far—using a design that enables operation at high current densities.