## 2 Materials and Methods
### Artificial Settings of IPR Conditions  
With the aim of verifying the physical mechanism of IPR, the second set of experiments is consequently conducted under artificially generated conditions established by a non-harmonic electric current feeding the exposure coil, to compensate for fluctuations in the static magnetic field background and maintain its consistency and orientation. The driving signal consists of a direct current component, responsible for generating a DC MF component within the coil cavity, and a harmonic component, responsible for producing a harmonic AC MF component with frequency of 50 Hz. The level of the DC component is adjusted to a degree where any fluctuations in the distribution of the geomagnetic field can be disregarded, which resulted in the excitation current described in Equation (7). If the artificial conditions are set to 5 times the GMF, the resonance conditions should be secured. The ion cyclotron frequencies listed in Table 4 are determined based on the magnetic flux density measured at the laboratory's center, which is \(B_{\text{DC}}=50.92\) mT. When the static component of magnetic flux density is increased to 5 times the magnitude of the basic GMF, resonance can be induced at a cyclotron frequency that is 5 times higher, owing to the linear relationship between the parameters (as described in Equation (2)), or at other additional subharmonic frequencies \(n\) specific to the ion in question. Following this adjustment, the static magnetic flux density, 5 times the basic value \(5\cdot B_{\text{DC}}\), corresponds to 254.6 mT, and the corresponding cyclotron frequency \(5\cdot f_{\text{C}}\) for potassium ion K\({}^{+}\) targeting is 100 Hz. Consequently, resonance occurs at the 2 nd subharmonic frequency: \(f_{\text{C}(1/2)}=50\) Hz. \[i(t)=0.107\text{ A}+0.284\text{ Asin}\left(2\pi f_{\text{C}(1/2)}\ t\right) \tag{7}\]  
Figure 2: Vectors of the static magnetic flux density at individual positions of the exposure coil in the complete exposure configuration in 3D space. Each vector is a graphical representation in 3D space of values from the two last columns (\(B_{\text{DC}}\) and \(\alpha\)) of Table 3. The values of \(B_{\text{X}}\), \(B_{\text{Y}}\) and \(B_{\text{Z}}\) are Cartesian components of the respective \(B_{\text{DC}}\) in exact position, resulting in the values of \(B_{\text{DC}}\) and \(\alpha\) as presented in Table 3.  
Considering the IPR model, it is imperative that the vectors of the static and alternating components of the MF are combined in parallel. To achieve this, measurements using the designed magnetometer were performed at each of the sample's positions. As an example, shown in Figure 3, the measured angle \(\alpha\) reached a value of 9.66\({}^{\circ}\) in position C within the exposure coil powered by the non-harmonic current producing a DC component five times the magnitude of the GMF. This deviation can be regarded as insignificant. The final requirement is that the maximum biological effect should be achieved when the magnitude of the alternating component is 1.8 times higher than the magnitude of the DC MF component, which can be expressed as follows:  
\[B_{\text{AC}}=1.8\cdot B_{\text{DC}}=1.8\cdot 254.6\cdot 10^{-6}\text{ T}=458.28\ \upmu\text{T}. \tag{8}\]