材料中氢同位素行为热脱附谱实验方法研究

材料中氢同位素行为研究是确保聚变堆安全和经济性的关键问题和重要研究方向。为研究材料中氢同位素的扩散、释放、居留等特性，建立了一种联合四极质谱仪（QMS）的热脱附谱（TDS）实验方法，解决了TDS系统超高真空、低氢同位素质谱本底、线性升温速率控制以及灵敏度标定等关键科学技术问题。通过涡轮分子泵和二级溅射离子泵实现了优于1×10^-7Pa的超高真空，本底H₂分压降至1×10^-9Pa。通过MCGS直流PID控温程序实现样品升温速率在1～100 K/min范围可调，采用漏率可变的特制通导型玻璃漏孔标定TDS系统的氘气脱附速率灵敏度，确定该灵敏度系数α和最小可检测氘气热脱附速率（脱附速率灵敏度）分别为6.22×10²⁴s^-1·A^-1、1.24×10^-10s^-1。采用镀镍Zr-4合金吸氘样品验证了TDS方法的有效性，初步分析了Zr-4中的氘热脱附特性。

Thermal Desorption Spectroscopy for Investigating Hydrogen Isotope Behavior in Materials

The behavior of hydrogen isotope generated in fusion reactor materials is the key issue for safety and economic operation of fusion reactors and becomes an interesting field. In order to investigate the mechanism of hydrogen isotope such as diffusion, release and retention, a high-sensitivity thermal desorption spectroscopy (TDS) in combination with a quadruple mass spectrometer (QMS) was developed. A major technical breakthrough in ultrahigh vacuum (UHV), low hydrogen background, linear heating and sensitivity calibration of TDS system was made. UHV of 1×10^-7 Pa and low hydrogen background of 1×10^-9 Pa were obtained by combining turbo molecule pump and sputter ion pump. Specimens can be linearly heated up to 1 173 K at the rate of 1 to 50 K/min under the MCGS PID software. Sensitivity calibration of the TDS system was accomplished using a special deuterium leak in the detector mode of QMS second electron multiplie. The desorption sensitivity coefficient and the minimum detection limit of deuterium desorption rate are 6.22×10²⁴s^-1·A^-1 and 1.24×10^-10s^-1, respectively. The measurement was also routinely conducted on a specimen of standard, deuterium containing Zr-4 alloy maintained in the laboratory, so as to validate the TDS method.