State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, 100190, China.
College of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing, 100049, China.
Sci Rep. 2023 Jun 19;13(1):9932. doi: 10.1038/s41598-023-37005-3.
Free-falling cubic Test Masses (TMs) are a key component of the interferometer used for low-frequency gravitational wave (GW) detection in space. However, exposure to energetic particles in the environment can lead to electrostatic charging of the TM, resulting in additional electrostatic and Lorentz forces that can impact GW detection sensitivity. To evaluate this effect, the high-energy proton data set of the Geostationary Operational Environmental Satellite (GOES) program was used to analyze TM charging due to Solar Proton Events (SPEs) in the 24th solar cycle. Using the Geant4 Monte Carlo toolkit, the TM charging process is simulated in a space environment for SPEs falling into three ranges of proton flux: (1) greater than 10 pfu and less than 100 pfu, (2) greater than 100 pfu and less than 1000 pfu, and (3) greater than 1000 pfu. It is found that SPEs charging can reach the threshold within 535 s to 18.6 h, considering a reasonable discharge threshold of LISA and Taiji. We demonstrate that while there is a somewhat linear correlation between the net charging rate of the TM and the integrated flux of [Formula: see text] 10 MeV SPEs, there are many cases in which the integrated flux is significantly different from the charging rate. Therefore, we investigate the difference between the integral flux and the charging rate of SPEs using the charging efficiency assessment method. Our results indicate that the energy spectrum structure of SPEs is the most important factor influencing the charging rate. Lastly, we evaluate the charging probability of SPEs in the 24th solar cycle and find that the frequency and charging risk of SPEs are highest in the 3rd, 4th, 5th, 6th, and 7th years, which can serve as a reference for future GW detection spacecraft.
自由下落的立方测试质量（TM）是用于空间低频引力波（GW）探测的干涉仪的关键组成部分。然而，暴露于环境中的高能粒子会导致 TM 静电充电，从而产生额外的静电和洛伦兹力，这可能会影响 GW 探测的灵敏度。为了评估这种影响，使用地球静止轨道运行环境卫星（GOES）计划的高能质子数据集，分析了第 24 太阳周期中太阳质子事件（SPE）导致的 TM 充电。使用 Geant4 蒙特卡罗工具包，在空间环境中模拟了 TM 充电过程，模拟了三种质子通量范围的 SPE：（1）大于 10 pfu 且小于 100 pfu，（2）大于 100 pfu 且小于 1000 pfu，以及（3）大于 1000 pfu。结果表明，考虑到 LISA 和太极的合理放电阈值，SPE 充电可以在 535 s 到 18.6 h 内达到阈值。我们证明，虽然 TM 的净充电率与[Formula: see text]10 MeV SPE 的积分通量之间存在一定的线性相关性，但在许多情况下，积分通量与充电率有很大的不同。因此，我们使用充电效率评估方法研究 SPE 的积分通量与充电率之间的差异。我们的结果表明，SPE 的能谱结构是影响充电率的最重要因素。最后，我们评估了第 24 太阳周期中 SPE 的充电概率，发现第 3、4、5、6 和 7 年 SPE 的频率和充电风险最高，这可为未来的 GW 探测航天器提供参考。
