## 3 Results and Discussion  
### Measurement of Magnetic Hysteresis Curve of Actuator Core  
Since the magnetic properties of amorphous materials are by default specified by the manufacturers in relation to their toroidal shapes, the presented measuring workstation based on the stray magnetic field measuring method was used to experimentally determine a response of an open-ended sample to an applied external magnetic field. The object of measurement was a ferromagnetic core intended for use as an element of amplifying the power of the electromagnetic actuator. The investigated core was made by folding annealed Co-based VITROVAC 6025 amorphous metallic ribbons with a typical F-type hysteresis curve. The final product contains 120 of these superimposed ferromagnetic ribbons in a composition forming a prismatic shape with dimensions of 80 \(\times\) 4 \(\times\) 2.4 mm and a volume of 768 mm\({}^{3}\). In the context of the geometrical parameters of the core, it should be noted that due to the coil's physical dimensioning (see the previous chapter), the systematic error caused by the inhomogeneity of the generated excitation field can be, in this case, negligible during the measurement. Before the measurement initialization, the investigated core was demagnetized by an externally applied alternating magnetic field with a gradually decreasing amplitude to remove residual magnetization. Moreover, to suppress an undesired inducted constant offset caused by the geomagnetic field or magnetic fields of active devices included in the measurement process, the measuring stand was aligned in the proper direction, in which this parasitic effect can be with respect to the magnetometer probe neglected. In order to optimize the measurement process, the measuring workstation was configured by application software under the consideration of the ferromagnetic core properties and specifications of the used magnetometer. Therefore, besides the calibration constants of the measuring probe, the maximum excitation current value and the probe's distance from the magnetized core were defined as the necessary input parameters. With the intention to achieve the saturation state of the magnetized core, considering its volume, the maximum excitation current was set to a value of 104,857.6 bits, corresponding to 2 A. Concerning the position of the measuring probe sensitivity point, it was separated from the center of the core by an equatorial distance of 157.064 mm during the measurement, thus complying with the conditions given by the used mathematical apparatus. At this point, the stray magnetic field was measured with a defined step of 200 bits, which for a range of 0 to the maximum set value of the excitation current (2 A), gives 524.3 measuring points (rounded to 524 by the application software). For each set excitation current value, the 200 samples of the stray magnetic field were measured and subsequently used for further statistical processing, the essence of which was to numerically suppress measurement uncertainties caused by induced noises of a local environment, like an ambient grid system with a standard industrial frequency. The measured hysteresis curve of the investigated ferromagnetic core is depicted in Figure 6.  
Part of Figure 6 is also the magnetization curve of the same core measured without the use of the designed measuring workstation (red curve). In this case, the measurement method was based on ferromagnetic core magnetization using an actuator excitation winding. From the technical point of view, such a measurement hardware configuration corresponds to a fully functioning electromagnetic actuator whose winding was during the measurement supplied with a time-varying current to generate an excitation magnetic field, while the compensation coil and the mathematical apparatus for the material's real-time state of magnetization determination were not included into the measuring chain.