Sunspot magnetic fields: a comparison between the CrAO and SDO/HMI data

We performed a digitization of maximum magnetic field measurements in sunspots. The original data were acquired as drawings at the Crimean Astrophysical Observatory of the Russian Academy of Sciences (CrAO RAS). About 1000 sunspots observed in 2014 have been analyzed. The data were compared to the corresponding measurements from the SDO/HMI instrument (with both the line-of-sight magnetic field Bz(HMI) and the modulus of the magnetic field vector B(HMI)). For the same sunspot, the maximum modulus of the magnetic field derived at CrAO was compared to the corresponding value from HMI. The Crimean data and the space-based data (of both types) were found to be in direct proportion to each other. A linear approximation over the entire range of measurements (1–4) kilogauss (kG) shows a Pearson correlation coefficient of 0.71 (with the 95 % confidence boundaries of 0.68–0.74) and a slope of linear regression of 0.65±0.02 for both types of the space-based data. A linear approximation over the range of strong fields B(CrAO) > 1.8 kG gives a similar correlation, however the slope of linear regression is far closer to unity and constitutes 0.90 for the relationship (Bz(HMI) vs B(CrAO)) and 0.84 for the relationship (B(HMI) vs B(CrAO)). In the range of weak fields B(CrAO) < 1.8 kG, a non-linear deviation (exceeding) of the space-based data is observed. Non-linearity can be explained, in part, by a specific routine of the magnetic field measurements at CrAO, however further investigations are needed to explore sources of possible non-linearity in the HMI data. The Crimean measurements of the maximum magnetic field in sunspots are concluded to be in good agreement with the corresponding SDO/HMI measurements, and therefore they can be used for scientific purposes.

Radial Evolution of Coronal Mass Ejections in the Inner Heliosphere: Catalog and Analysis

&lt;p&gt;Our knowledge of the properties of Coronal Mass Ejections (CMEs) in the inner heliosphere is constrained by the relative lack of plasma observations between the Sun and 1 AU. In this work, we present a comprehensive catalog of 47 CMEs measured in situ measurements by two or more radially aligned spacecraft (MESSENGER, Venus Express, STEREO, and Wind/ACE). We estimate the CME impact speeds at Mercury and Venus using a drag-based model and present an average propagation profile of CMEs (speed and deceleration/acceleration) in the inner heliosphere. We find that CME deceleration continues past Mercury's orbit but most of the deceleration occurs between the Sun and Mercury. We examine the exponential decrease of the maximum magnetic field strength in the CME with heliocentric distance using two approaches: a modified statistical method and analysis from individual conjunction events. Findings from both the approaches are on average consistent with previous studies but show significant event-to-event variability. We also find the expansion of the CME sheath to be well fit by a linear function. However, we observe the average sheath duration and its increase to be fairly independent of the initial CME speed, contradicting commonly held knowledge that slower CMEs drive larger sheaths. We also present an analysis of the 3 November 2011 CME observed in a longitudinal conjunction between MESSENGER, Venus Express, and STEREO-B focusing on the expansion of the CME and its correlation with the exponential fall-off of the maximum magnetic field strength in the ejecta.&lt;/p&gt;

TWO DIPOLE MAGNETIC SYSTEMS FOR TECHNOLOGICAL ELECTRON ACCELERATOR

For a 10 MeV technological accelerator, a dipole magnet with a permanent magnetic field was created using the SmCo alloy. The maximum magnetic field in the magnet gap was 0.3 T. The magnet is designed to measure the energy of the beam and to adjust the accelerator for a given energy. For a linear accelerator with an energy of 23 MeV, a dipole magnet based on the Nd-Fe-B alloy was developed and fabricated. It was designed to rotate the electron beam at a 90 degrees. The magnetic field in the dipole magnet along the path of the beam was 0.5 T. The effective length of the magnet was 242 mm.

Effect of Shape of Magnet on the Machining of Workpiece

Viscoelastic Magnetic Abrasive finishing has achieved a wide popularity in the field of finishing as the process is capable of finishing Non-ferrous material along with the ferrous material. With the development in technology the quality and surface finish attract more attention as compare to the machining perfection and dimensional accuracy. The present paper consists of comparison of four type of magnet available in the market and one of them as self-proposed electromagnet. A single aluminium hollow cylindrical workpiece of outer diameter as 10 mm and the inner diameter as 8 mm is finished by taking the magnet one by one whose dimensions are made according to the available literature and market and are placed as two magnetic poles with 180 degrees apparats. Ansys Maxwell 16 software was used to predict the value of maximum magnetic field on the workpiece due to the shape of the magnet and it was found that the maximum magnetic field was produced by fan shape magnet of about 0.6 Tesla. From the idea of magnetic field intensity of the workpiece, the machining ability of the magnet in viscoelastic magnetic field can be produced.

Изучение влияния временных характеристик модулированной DC-плазмы с (SiH-=SUB=-4-=/SUB=--Ar-O-=SUB=-2-=/SUB=-)-газовой фазой на рост ncl-Si в матрице a-SiO-=SUB=-x-=/SUB=-:H (C-=SUB=-O-=SUB=-2-=/SUB=--=/SUB=-=15.5 мол%)

The effect of various operating conditions of time-modulated DC (direct current) plasma on the formation of an amorphous a -SiO_ x :H matrix and silicon nanoclusters is studied using IR (infrared) and photoluminescence spectra. DC-plasma modulation consists in repeated ( n = 180) switching off and on of the magnetron magnet coil with various time combinations, t _off = 1, 2, 5, 10, 15 s and t _on = 5, 10, 15 s, respectively, at a fixed oxygen concentration ( $${{C}_{{{{{\text{O}}}_{{\text{2}}}}}}}$$ = 15.5 mol %) in a (SiH_4 + Ar + О_2) gas mixture. The positive effect of self-induction on the formation of both the amorphous matrix and silicon nanoclusters is confirmed. The largest values of x in a -SiO_ x :H and photoluminescence intensity are observed in the case of the combination of prolonged plasma residence in the working state ( t _on = 10–15 s) and the maximum magnetic-field strength. The effect of t _off on the processes of the formation of both the a -SiO_ x :H matrix and silicon nanoclusters is also noted.

On Slowly Rotating Magnetized White Dwarfs

Rotating magnetized white dwarfs are studied within the framework of general relativity using Hartle’s formalism. Matter inside magnetized white dwarfs is described by an equation of state of particles under the action of a constant magnetic field which introduces anisotropic pressures. Our study is done for values of magnetic field below [Formula: see text] G - a threshold of the maximum magnetic field obtained by the cylindrical metric solution - and typical densities of WDs. The effects of the rotation and magnetic field combined are discussed, we compute relevant magnitudes such as the moment of inertia, quadrupole moment and eccentricity.

Technological Features Influence on Magnetic Sensitivity of Ferromagnetic Structures

The main urgent problems of the magnetic devices and primary conventers development based on the magnetoresistive structures are the sensitivity improvement and thermal stability. This paper discusses how to use the magnetoresistive structures based on nanoscale films of permalloy Ni (80%) Fe (20%) in the sensory systems. It is shown the variation of the shape and size ratio of magnetoresistive elements influences the characteristics of the magnetization and the dynamic range of the sensors, as well as maximum magnetic field sensitivity. The optimization of magnetoresistive structures topological sizes was carried out and sensor design with the highest sensitivity was chosen. It is shown that sensitivity of sensors can achieve value of 20.7 (mV/V)/(kA/m) by changing bias field. The ability to function in a large temperature range with coefficient of thermal stability - 0.35 %/°С was demonstrated for the obtained magnetoresistive structures.