A method of estimating the lower bound of coronal magnetic field strength in the neighborhood of an ejecting plasmoid is presented. Based on the assumption that the plasma ejecta is within a magnetic island, an analytical expression for the force acting on the ejecta is derived. The method is applied to a limb coronal mass ejection event, and a lower bound of the magnetic field strength just below the CME core is estimated. The method is expected to provide useful information on the strength of reconnecting magnetic field if applied to X-ray plasma ejecta.
The mechanical properties of ceramics materials can be tailored by designing their microstructures. We have reported that development of texture can be controlled by slip casting in a strong magnetic field followed by heating even for diamagnetic ceramics such as alumina. A strong magnetic field of 12T was applied to the suspension indcuding alumina powder to rotate each particle during slip casting. The sintering was conducted at the desired temperature in air without a magnetic field. C-axis of alumina was parallel to the magnetic field. Bending strength of textured alumina depended on the direction of oriented microstructure.
The morphology and strength of the primordial magnetic field which is generated spontaneously in the early universe are studied for three models: (1) inflation (2) primordial magnetized bubble and (3) primordial turbulence models, We calculate the power spectra of magnetic field that are scale-free and proportional to k1.5,k3~4 and k2/3, respectively. The configurations of magnetic field having these power spectra are visualized. To constrain the present strength of the primordial magnetic field we calculate the anisotropy of the microwave background radiation in Bianchi type I universe with globally homogeneous magnetic field. From the COBE limit of the quadrupole moment of (δT/T)l=2 the present strength of horizen-scale magnetic fields Bp is constrained to be less than 9 × 10-8G.
In order to know how the magnetic field increases with density in interstellar clouds, we have analyzed observations of extinction and polarization for stars in the ρ Oph molecular cloud complex. The size of grains in dense parts of the complex is estimated to be larger than the ones in diffuse interstellar clouds by about 15 percent in radii. Employing the Davis-Greenstein mechanism for grain alignment with this estimated grain size, we have put constraints on the exponent in the field-density relation B ∝ n x : 1 / 5 ≤ x ≤ 1 / 3 . It is concluded that magnetic field in gravitationally contracting clouds increases less steeply than the classical expectation based on the approximation of isotropic contraction with complete frozen-in flux.