Geochemistry of the frost mound’s ice in the Sentsa River Valley (Oka plateau, East Sayan Mnt.)

The authors have studied the chemical composition of ground ice sampled from the frost mounds located in the unconsolidated sediments of the Sentsa River valley (Oka plateau, Eastern Sayan Mountains) to reconstruct the formation history of these cryogenic creations. Numerous frost mounds of various sizes are mainly composed of clayey silts with interlayers of heavy silts and ice lenses. It is found that the chemical composition of the melt ice sampled from lenses and layers within the frost mounds is HCO3 Ca, SO4-HCO3 Ca and NH4-HCO3 Ca with 6.5–15.6 mg/L salinity and pH = 5.6÷6.1. Whereas, the salinity of the melt texture-forming ice sampled from the ice with fractions of enclosing clayey silts was much higher: from 50 up to 792.5 mg/L. River and lake water is ultra-fresh HCO3 Ca with 99–132 mg/L salinity. The geochemical features of ground ice depend on a water-rock interaction, a presence of organic matter in the unconsolidated sediments and a repeated volcanic activity. The frost mounds are confined to a lacustrine sediments area in the backwater zone that was formed by the Late Pleistocene end moraine. The frost mounds have probably a mixed segregation-injection genesis.

Magnetization Method Design of Bulk Multi-Seeded High Temperature Superconductors

The potential application of bulk high temperature superconductor (HTS) magnets has attracted much attention because of the potential high trapped flux in HTS magnets. This paper focuses on the magnetization method design of bulk multi-seeded HTS magnets for obtaining their better flux-trapping performance. Firstly, three different magnetization methods were carried out based on the current experimental setup to find a better way of magnetizing a bulk melt-texture three-seeded YBaCuO superconductor. The experimental results indicated that when the three domains of this three-seeded YBaCuO bulk were magnetized in order, the maximum trapped flux was higher than that when only one domain was magnetized. However, this method costs about three times of the magnetization time than the other two methods and the increasing ratio was only about 11.11%. It has been found that another method of magnetizing only the middle domain could also get a good result such as the uniformity of trapped flux is good. In order to improve the current experimental magnetization conditions for further improvement, two sheets of iron were designed to attach two poles of the electromagnet (Lakeshore, Model EM4-CV) for increasing the magnetizing area, and that all domains of a bulk multi-seeded HTS can be magnetized in one time. Firstly, the appropriate size and thickness of the iron sheets was simulated and optimized by Comsol Multiphysics. It has been found that the magnetic field between two poles was highest when the thickness of iron was 2 mm and the length was 68 mm. Then, the simulating and optimization results had been verified by the following experiments. According to the comparison experiments, it is proved that to choose the magnetization method that only magnetizing the middle domain with the improved setup is helpful to obtain larger and more homogeneous magnetic flux for the bulk multi-seeded HTS magnet due to the added iron sheets.