Toroidal models of magnetic field with twisted structure

We present and discuss properties of the following magnetic field models in a magnetic cloud: Miller and Turner solution, modified Miller–Turner solution, Romashets–Vandas toroidal and integral models, and Krittinatham–Ruffolo model. Helicity of the magnetic field in all the models is the main feature of magnetic clouds. The first three models describe the magnetic field inside an ideal torus. In the integral model, parameters of a generating torus ambiguously determine the volume and form of the magnetic field region. In the Krittinatham–Ruffolo model, the cross-section radius of the torus is variable, thereby it corresponds more closely to the real form of magnetic clouds in the inner heliosphere. These models can be used to interpret in-situ observations of the magnetic flux rope, to study a Forbush decrease in magnetic clouds and transport effects of solar energetic particles injected into a coronal mass ejection.

Toroidal models of magnetic field with twisted structure

We present and discuss properties of the following magnetic field models in a magnetic cloud: Miller and Turner solution, modified Miller–Turner solution, Romashets–Vandas toroidal and integral models, and Krittinatham–Ruffolo model. Helicity of the magnetic field in all the models is the main feature of magnetic clouds. The first three models describe the magnetic field inside an ideal torus. In the integral model, parameters of a generating torus ambiguously determine the volume and form of the magnetic field region. In the Krittinatham–Ruffolo model, the cross-section radius of the torus is variable, thereby it corresponds more closely to the real form of magnetic clouds in the inner heliosphere. These models can be used to interpret in-situ observations of the magnetic flux rope, to study a Forbush decrease in magnetic clouds and transport effects of solar energetic particles injected into a coronal mass ejection.

Mott-insulator-aided detection of ultra-narrow Feshbach resonances

We report on the detection of extremely narrow Feshbach resonances by employing a Mott-insulating state for cesium atoms in a three-dimensional optical lattice. The Mott insulator protects the atomic ensemble from high background three-body losses in a magnetic field region where a broad Efimov resonance otherwise dominates the atom loss in bulk samples. Our technique reveals three ultra-narrow and previously unobserved Feshbach resonances in this region with widths below \approx 10\,\mu≈10μG, measured via Landau-Zener-type molecule formation and confirmed by theoretical predictions. For comparatively broader resonances we find a lattice-induced substructure in the respective atom-loss feature due to the interplay of tunneling and strong particle interactions. Our results provide a powerful tool to identify and characterize narrow scattering resonances, particularly in systems with complex Feshbach spectra. The observed ultra-narrow Feshbach resonances could be interesting candidates for precision measurements.

An Electromagnetic Parameters Measuring System Based on a Concave Cylindrical Cavity

In this paper, an electromagnetic parameters measuring system based on a concave cylindrical cavity is presented. The concave cylindrical cavity resonator mode is with separated electric field and magnetic field distribution region, which is not observed in other cavities. It is shown that permittivity and permeability can be tested by placing samples in the strongest electric field region and magnetic field region, respectively. Therefore, by using this measurement system, the electromagnetic parameters of microwave absorbing materials can be accurately characterized.

Magnetic field structures inside magnetars with strong toroidal field

We have analyzed the magnetized equilibrium studies with strong toroidal magnetic fields and found that the negative toroidal current density inside the star is very important for the strong toroidal magnetic fields. The strong toroidal magnetic fields require the strong poloidal current, but the strong poloidal current results in the localized strong toroidal current density in the axisymmetric system. This localized toroidal current changes the magnetic field configuration and makes the size of the toroidal magnetic field region smaller. As a result, the toroidal magnetic field energy can not become large. We need to cancel out the localized toroidal current density in order to obtain the large toroidal fields solutions. We have found and showed that the negative toroidal current cancels out the localized toroidal current density and sustain the large toroidal magnetic field energy inside the star. We can explain the magnetized equilibrium studies with strong toroidal magnetic fields systematically using the negative current density. Physical meaning of the negative current is key to the magnetar interior magnetic fields.