Determination of the Heating Effect of Magnetic Fluid in Alternating Magnetic Field

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In this paper, we have investigated the heating power of magnetic fluid, when exposed to a high-frequency magnetic field. Commercially available sample of magnetic fluid has been used and some basic investigation revealed maghemite <formula formulatype="inline"><tex Notation="TeX">$\gamma$</tex></formula>-Fe<formula formulatype="inline"><tex Notation="TeX">$_{2}$</tex></formula>O<formula formulatype="inline"> <tex Notation="TeX">$_{3}$</tex></formula> particles with 10.9-nm mean diameter and 10.57% volume concentration. We present an improved experimental system, capable of generating homogeneous magnetic field of amplitudes up to 4 kA/m and frequencies from 10 kHz to 1 MHz. In this paper, none of the heating generation mechanisms (NÉel or Brownian relaxation or eddy current losses) have been determined solemnly, therefore, the outcome of their activity has been examined by two methods. In case of calorimetric measurements method key parameter is temperature rise while in case of magnetic measurement method key parameters are time-dependent magnetic field strength <formula formulatype="inline"> <tex Notation="TeX">$H$</tex></formula> and appurtenant magnetic flux density <formula formulatype="inline"><tex Notation="TeX">$B$</tex></formula>. Calorimetric measurements are performed and used to determine specific absorption rate curve. Alternatively, this curve has been obtained with the measurement of <formula formulatype="inline"><tex Notation="TeX">$B(t)$</tex></formula> and <formula formulatype="inline"><tex Notation="TeX">$H(t)$</tex></formula>, when a sample is exposed to the same magnetic conditions. Integration of the hysteresis loops has resulted in loss power of the fluid. Proposed magnetic measurement methods proved to be a decent alternative in the process of determining losses. </para>