How to move ionized gas: an introduction to the dynamics of HII regions

This review covers the dynamic processes that are important in the evolution and structure of galactic HII regions, concentrating on an elementary presentation of the physical concepts and recent numerical simulations of HII region evolution in a non-uniform medium. The contents are as follows: (1) The equations (Euler equations; Radiative transfer; Rate equations; How to avoid the dynamics; How to avoid the atomic physics). (2) Physical concepts (Static photoionization equilibrium; Ionization front propagation; Structure of a D-type front; Photoablation flows; Other ingredients - Stellar winds, Radiation pressure, Magnetic fields, Instabilities). (3) HII region evolution (Early phases: hypercompact and ultracompact regions; Later phases: compact and extended regions; Clumps and turbulence).Comment: To be published as a chapter in 'Diffuse Matter from Star Forming Regions to Active Galaxies' - A volume Honouring John Dyson. Eds. T. W. Harquist, J. M. Pittard and S. A. E. G. Falle. 25 pages, 7 figures. Some figures degraded to meet size restriction. Full-resolution version available at http://www.ifront.org/wiki/Dyson_Festschrift_Chapte

Thickness-Dependent Permanent Magnet Properties of ZrCo Thin Films Grown on Si with Pt Underlayer

Yuzuak GD, Yuzuak E, Teichert N, Hütten A, Elerman Y. Thickness-Dependent Permanent Magnet Properties of ZrCo Thin Films Grown on Si with Pt Underlayer. METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE. 2017;48A(5):2654-2659.Zr-Co is one of the essential magnetic materials due to its interesting magnetic and structural properties. In this work, we studied the magnetic and structural properties of ZrCo thin films of different thicknesses grown on Si substrate with Pt underlayer. The structural properties and chemical composition of the ZrCo films were investigated by X-ray diffraction analysis, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis, and atomic force microscopy-magnetic force microscopy measurements. The saturation magnetization, M(H) characteristic, and Henkel plots of the Zr-Co films were obtained by vibrating-sample magnetometry. The results show that and were enhanced with decreasing layer thickness of Zr-Co. For 10-nm ZrCo with 20-nm Pt underlayer thin film, we observed coercive field of 2 kOe with energy product of 0.7 MGOe. Our results may be valuable for use of ZrCo thin films in nanomagnet applications