## 3 Results  
### Irradiation Test Results  
The transmission-mode side of the wireless communication module was placed within the irradiation chamber, and irradiation was conducted while performing wireless communication. Tables 4-6 list the representative SEUs measured under Ar, Kr, and Xe irradiation, respectively. For each measurement, continuous observation was performed until an SEU occurred. Then, the IC was reset, and the next test sequence was initiated. During measure  
Figure 8: PC for data monitoring during irradiation tests.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Ion** & **LET [MeV/(mg/cm\({}^{2}\))]** \\ \hline Ar & 19.4 \\ Kr & 42.4 \\ Xe & 61.9 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Ion species and LET values.  
ments 2 and 3 under Xe irradiation (Table 6), many bit errors resulting from SEUs occurred almost simultaneously; the total number of bit errors is shown.  
The upset cross-section was calculated using the following equation [21]:  
\[\sigma=\frac{A}{T\times b\times f} \tag{1}\]  
where \(\sigma\) is the upset cross-section [cm\({}^{2}\)/bit]; \(A\) is the number of SEUs [times]; \(T\) is the measurement time [s]; \(b\) is the number of target bits [bits]; and \(f\) is the fluence rate [times/s/cm\({}^{2}\)].  
The wireless communication module has 256 bytes of RAM and several registers for external control and configuration, with various command formats. In this device, if the radiation changes a register value, the prescribed wireless communication becomes impossible. To account for this, \(b\) of the test object was calculated using Equation (1) as twice the installed memory capacity, considering the existence of the register. For the case of no SEU occurrence, the \(\sigma\) calculation assumes that an SEU occurs once, under the basis that the probability of an SEU occurring under operation in a space environment is never zero.  
The irradiation test results confirmed that SEUs were generated in the wireless communication module by each ion beam. The SEU occurrence frequency was the highest under Xe irradiation, which had the highest LET value. In addition, for each ion beam, communication operation on the transmission-mode side stopped several times as a result of SEU-occurrence error detection. In such cases, wireless communication was facilitated once again by reclosing the power.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Measurement No.**} & \multirow{2}{*}{**No. of SEUs**} & **Measurement Time** & **Upset Cross-Section** \\  & & **[s]** & **[cm\({}^{2}\)/bit]** \\ \hline
1 & 2 & 484 & \(3.54\times 10^{-9}\) \\
2 & \(391\) & 170 & \(1.97\times 10^{-6}\) \\
3 & 114 & 668 & \(1.46\times 10^{-7}\) \\
4 & 2 & 1509 & \(1.14\times 10^{-9}\) \\
5 & 0 & 380 & \(2.26\times 10^{-9}\) \\ \hline \hline \end{tabular}
\end{table}
Table 6: SEU results under Xe irradiation.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Measurement No.**} & \multirow{2}{*}{**No. of SEUs**} & **Measurement Time** & **Upset Cross-Section** \\  & & **[s]** & **[cm\({}^{2}\)/bit]** \\ \hline
1 & 1 & 201 & \(7.95\times 10^{-9}\) \\
2 & 0 & 1201 & \(1.33\times 10^{-9}\) \\
3 & 2 & 389 & \(8.21\times 10^{-9}\) \\
4 & 2 & 901 & \(3.55\times 10^{-9}\) \\
5 & 0 & 453 & \(3.53\times 10^{Under Kr and Xe irradiation, a phenomenon that may have been an SEL was observed. The current consumption, which was 110 mA during normal communication operations, approximately doubled to 260 mA; however, the wireless communication module continued to function as normal. When the power supply was reclosed, the current returned to the normal value, and normal wireless communication before and during irradiation was confirmed. Therefore, the wireless communication module test object was not permanently damaged by the short SEL-induced current increase.