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Hot plasma is highly conductive in the direction parallel to a magnetic field. This often means that the electrical potential will be nearly constant along any given field line. When this is the case, the cross-field voltage drops in open-field-line magnetic confinement devices are limited by the tolerances of the solid materials wherever the field lines impinge on the plasma-facing components. To circumvent this voltage limitation, it is proposed to arrange large voltage drops in the interior of a device, but coexist with much smaller drops on the boundaries. To avoid prohibitively large dissipation requires both preventing substantial drift-flow shear within flux surfaces and preventing large parallel electric fields from driving large parallel currents. It is demonstrated here that both requirements can be met simultaneously, which opens up the possibility for magnetized plasma tolerating steady-state voltage drops far larger than what might be tolerated in material media. In open-field-line magnetic plasma traps, the attainable cross-field voltage drops are limited by the tolerances of the solid materials of the vacuum vessel. Here, the authors demonstrate the possibility of equilibria that isolate large voltage drops to the interior of the plasma, circumventing this limit.

The Centrifugal Mirror Fusion Experiment (CMFX) at the University of Maryland, College Park is a rotating mirror device that utilizes a central cathode to generate a radial electric field which induces a strongly sheared azimuthal E × B flow to improve plasma confinement and stability. The fusion yield of CMFX plasmas is assessed by diagnosis of neutron emission for the first time. The total neutron yield is measured with two xylene (EJ-301) and deuterated-xylene (EJ-301D) liquid scintillator detectors absolutely calibrated with an in silico method. A larger xylene scintillator was cross-calibrated and used to measure the time dynamics of the fusion rate under various experimental conditions. A permanently installed 3He gas tube detector was independently calibrated with a Cf-252 neutron source to make total yield measurements and provide an independent validation of the scintillator calibration. An interpretive modeling framework was developed using the 0D code MCTrans++ (Schwartz et al 2024 J. Plasma Phys. 90 905900217) to infer undiagnosed plasma parameters such as density, temperature, and confinement time. A peak neutron emission rate of 8.4×106±7.0×105 was measured (neglecting modeling uncertainties), with an inferred triple product of 1.9×1017 m−3 keV s from 0D modeling.

This study aims to examine the influence law of polyhedron structure on the spatial mechanical properties of ultra-high-speed rotating mirrors. To this end, polyhedral beryllium alloy rotating mirrors are investigated on the basis of elastoplastic theory and finite element method. The maximum stress is located at the end position of the contact between the shaft and the mirror body. Stress increases with the number of mirror faces. The different structures have a negative stress gradient. The structural strength of rotating mirror is affected by the strength of the mirror body material in high-speed rotation of the tensile force of centrifugal force. The lateral deformation of the mirror surface is caused by the combined effect of compression of centrifugal force generated by the material of sharp-corner and the tretching of tensile force caused by the material at the centre of the mirror at high-speed rotation. The amount of mirror surface deformation is not proportional to the number of faces. The rotating mirror with iso-quadrangular structure has the best lateral deformation effect. This research provides a theoretical basis for the research and design of rotating mirrors with high potential value.

Flows over a disc are studied in a wind tunnel over incidence angles between $0^\\circ \\text { and }36^\\circ$, a Reynolds number of $2.7 \\times 10^4$ and rotational speed ratios of $0\\unicode{x2013}10$. Smoke-wire visualization, particle image velocimetry and hot-film anemometry are employed. Two vortex shedding modes originating from the upstream surface of the disc are observed. The first is dominant at incidence angles up to ${\\sim }21^\\circ$. Beyond $21^\\circ$, the second mode dominates. It appears as a soliton on the vortices and has a shedding frequency nearly twice that of the first at the highest incidence angle. The Strouhal number monotonically increases with incidence angle from approximately 0.2 to 0.4. Spectral analysis of the hot-film measurements confirms the findings from flow visualization experiments. Flows over the spinning disc generally mimic the stationary disc flows; however, centrifugal forces lead to cross-stream instability features that may be attributed to spiral wave instabilities intrinsic to the boundary layers in rotating flows. Velocity measurements are used to construct streamline patterns to compare with the smoke streaklines. The unsteadiness of the flows results in large variances. Mean strain rates are extracted from velocity data, where the fixed disc case at normal incidence compares well with theoretical predictions. The unsteady boundary layer thickness over the fixed disc, however, is approximately twice that predicted by theory for steady flow, stemming from the dominance of large unsteady vortices. Limited comparisons are made of the Strouhal numbers from experiments and numerical calculations in the literature.

Plasma flow and acceleration in the converging-diverging magnetic field configuration, such as magnetic nozzle in electric propulsion and open magnetic mirrors for fusion applications are considered. This work analyses plasma acceleration in the magnetic nozzle with an emphasis on the electromagnetic effects and centrifugal forces due to plasma rotation. Intrinsic coupling of the azimuthal rotation and azimuthal magnetic field is analyzed, and additional plasma acceleration due to the conversion of the energy of the azimuthal magnetic field and azimuthal rotation is demonstrated. For large expansion in the diverging magnetic field plasma flow velocities may approach and exceed the Alfvén velocity. In these regimes, stationary solutions for the transonic and trans-Alfvénic flows have been obtained that demonstrate the existence of the unique regular solution passing through all critical points within the MHD theory, i.e., the points where the plasma flow is equal to the signal velocities of the MHD modes: slow and fast magnetohydrodynamic waves and Alfvén wave. The time-dependent initial value simulations show that stationary equilibrium flows are robust and stable, so that time-dependent solutions converge toward stationary solutions.

The manufacturing technology of aspheric optical components is not only a difficult problem in the field of advanced optical manufacturing, but also an important symbol to measure the development level of a country's manufacturing industry. The traditional aspheric optical component processing method has the disadvantages of long processing time, large waste of materials and high processing cost. Aspherical mirror by centrifugal casting is a new processing technology. it can save a large amount of material, reduce processing time, suitable for producing various sizes of aspheric optical elements, especially in processing large size aspheric lens have obvious advantages. In this paper, the processing technology of aspherical mirror blank is introduced. Experiment with rosin, which simulation process of glass by centrifugal melt casting. The shape of the aspherical mirror is calculated by calculating. After the experiment of K9 material, the surface of optical glass is obtained. The feasibility of this method is proved by experiments. It is proved that this method can be used to manufacture aspheric mirror.

Optical mirrors have high requirements for surface precision, requiring ultra-precision processing. The revolving movement of a computer-controlled optical surfacing (CCOS) grinding system will induce vibrations in a five-degrees-of-freedom hybrid processing robot (5-DOF-HPR) and a flexible support system (FSS) in a large optical mirror processing system (LOMPS). As a result, the mirror surface will vibrate, which will ultimately affect the surface accuracy of the final optical mirror. Therefore, the differential equation representing the vibration of the 5-DOF-HPR is established based on the spatial beam unit, which transforms the generalized coordinates into modal coordinates, thereby removing the coupling terms of the vibration differential under generalized coordinates. At the same time, a dynamic analysis of the CCOS grinding system is performed, and the magnitude and direction of the centrifugal force and reaction force are calculated. Then, the natural frequencies of the 5-DOF-HPR and the FSS are measured experimentally and compared with the simulation results; thus, the accuracy and effectiveness of the model are verified. Finally, the vibration characteristics of the processed optical mirrors under different influencing factors are obtained. A theoretical and experimental basis for parameter optimization and path planning of the LOMPS is provided to improve the surface accuracy of the processed optical mirror.

Plasma flow and acceleration in the converging-diverging magnetic field configuration, such as magnetic nozzle in electric propulsion and open magnetic mirrors for fusion applications are considered. This work analyses plasma acceleration in the magnetic nozzle with an emphasis on the electromagnetic effects and centrifugal forces due to plasma rotation. Intrinsic coupling of the azimuthal rotation and azimuthal magnetic field is analyzed, and additional plasma acceleration due to the conversion of the energy of the azimuthal magnetic field and azimuthal rotation is demonstrated. For large expansion in the diverging magnetic field plasma flow velocities may approach and exceed the Alfven velocity. In these regimes, stationary solutions for the transonic and trans-Alfvenic flows have been obtained that demonstrate the existence of the unique regular solution passing through all critical points within the MHD theory, i. e. the points where the plasma flow is equal to the signal velocities of the MHD modes: slow and fast magnetohydrodynamic waves and Alfven wave. The time-dependent initial value simulations show that stationary equilibrium flows are robust and stable, so that time-dependent solutions converge toward stationary solutions.