## 4 Result and Discussion  
### Experimental Result  
The electron density values of the radial position according to the pressure variation in the experiment using SLP are shown in Figure 5. In the experimental data, the electron density shows a similar trend across all ranges and tends to increase at each radial position as the pressure increases. The electron temperature values of the radial position according to the pressure variation in the experiment using SLP is shown in Figure 6. In the experiment, except for the data value at 30 mTorr, the electron temperature shows an increasing tendency at the 15 mm radial position and then decreases continuously to the edge. Based on the pressure range, the electron temperature generally tends to gradually decrease from the center to the edge, and the plasma density at the center is typically larger than that at the edge [34; 35]. Our results confirmed that the plasma parameters in bulk plasma are dominant in source power, and bias power cannot affect the parameters when compared to source power [23]. Figure 7 shows the electron temperature and electron density values at radial positions obtained by SLP due to bias power variation at 30 mTorr. In our experiment, the source power value was always in inductive mode (H-mode). Therefore, with the increase in bias power, the electron density value decreases and the electron temperature value increases [36].  
Figure 4: Pre-experiment on the process time to plasma generation.  
A wavelength selection experiment was conducted to use the line-ratio method of OES. Through the OES data as shown in Figure 8, the intensity value of the Ar wavelength was compared by referring to the reference [33], and peak with a constant tendency according to the parameter change was confirmed. Three peaks at 751.5 nm, 750.4 nm, and 419.8 nm were selected and then used to derive electron density and electron temperature. In general, there is a difference between the plasma parameter obtained through OES data and the SLP data [37].  
Figure 5: Experiment data of electron density of radial position by pressure variation.  
Figure 6: Experiment data of electron temperature of radial position by pressure variation.  
Figure 7: Experiment data of (**a**) electron density and (**b**) electron temperature of radial position by bias power variation at 30 mTorr.  
Figure 9 shows the normalization of the plasma parameter that was calculated using Equation (16). Although this obtained value is different from the experimental value, the result of normalization is significant with the tendency of the experimental value in the case of electron density. However, in the case of electron temperature, the value in the radial position tends to increase with the increase in pressure, in contrast to the trend that typically appears. As a result, the plasma parameter calculated as OES is different to the SLP data value but resembles the tendency. Additionally, the plasma parameter cannot be derived according to the variation in bias power through OES. As the bias power varied, the intensity value of a particular Ar peak remained constant and was identical to the intensity value calculated using corresponding pressure. Therefore, bias power cannot affect the intensity value because it is not the main factor for direct plasma generation. The electron density can be altered depending on the radial position by bias power that affects bulk plasma uniformity. In addition, the difference in potential affects the main parameters of WIP temperature, such as ion energy, so the effect of bias power must be considered [38]. Thus, ETSW is used to determine heat flux based on the variation in bias power.