Generation of a rotating high frequency magnetic field designed for use in magnetic hyperthermia

The paper presents two issues: a new method of generating a rotating magnetic field of high frequency and describes the influence of the rotating magnetic field high frequency on energy losses in a magnetic fluid. This new generation method uses a closed magnetic circuit with ferrite elements. It is powered by two high-frequency power amplifiers through transformers with ferrite cores. As a result, it is relatively easy to obtain high amplitude values ​​of the rotating magnetic field intensity. The article describes the results of the operation of rotating magnetic fields in the frequency range from 38 kHz to 370 kHz, with an amplitude of intensity up to 16 kA·m−1 on energy losses in a magnetic fluid. The obtained results indicate that at a constant frequency f the values ​​of the temperature rate increase dT/dt are proportional to the square of intensity of magnetic field ∝H2. Likewise, the values ​​of the rate of temperature increase dT/dt measured with the constant intensity of the rotating magnetic field H are proportional to the square of frequency ∝f2. It was found that in the area of ​​the low magnetic field intensity, energy losses resulting from magnetic relaxation prevail, which decrease with the increase of the field strength H, and then the share of losses due to magnetic hysteresis increases. A comparison of the calorimetric effect in a rotating and alternating magnetic field shows that the rotating field releases 75% more heat energy than the alternating field.