Characteristics of laser produced plasmas of hafnium and tantalum in the 1-7 nm region
Characteristics of laser produced plasmas of hafnium and tantalum in the 1-7 nm region
复制标题
1-7 nm 区域激光产生的铪和钽等离子体的特性
DOI：
10.1140/epjd/e2017-70830-6
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发表时间：
2017
影响因子：
1.8
通讯作者：
Higashiguchi Takeshi
中科院分区：
文献类型：
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作者：
Li Bowen;Otsuka Takamitsu;Sokell Emma;Dunne Padraig;O'Sullivan Gerry;Hara Hiroyuki;Arai Goki;Tamura Toshiki;Ono Yuichi;Thanh-Hung Dinh;Higashiguchi Takeshi
利用脉冲宽度分别为170ps和10 ns的两个脉冲分别工作在不同功率密度范围内的两个脉冲激光，在1-7 nm范围内记录了Hf和Ta激光产生的等离子体的软X射线(SXR)谱。最大聚焦峰值功率密度分别为2. 3×1014W cm-2(170ps脉冲)和1. 8×1012W cm-2(10 ns脉冲)。由n=4-n=4和n=4-n=5个未分辨跃迁阵列(UTA)产生的两个强的准连续强度带主宰了这两组实验光谱。与用Cowan原子结构代码进行的计算相比较，以及考虑到以前的实验和理论结果，有助于识别光谱中最突出的特征。对于10 ns的光谱，从那时=4-n=5的阵列可以识别出的最高离子能级低于类银Hf25+和Ta26+(具有4d~104f基态)，这表明所获得的等离子体温度太低，不能产生具有最外层4d亚壳层的离子，而对于170 ps等离子体，可以推断存在显著更高的能级，并且由于4d-5p跃迁的谱线明显明显。此外，我们还展示了双激光照射对钽发射的增强作用，并演示了预脉冲持续时间和两个脉冲之间的延迟时间的影响
AbstractSoft X-ray (SXR) spectra from hafnium and tantalum laser produced plasmas were recorded in the 1–7 nm region using two Nd:YAG lasers with pulse lengths of 170 ps and 10 ns, respectively, operating at a range of power densities. The maximum focused peak power density was 2. 3 × 1014W cm-2for 170 ps pulses and 1. 8 × 1012W cm-2for 10 ns pulses, respectively. Two intense quasicontinuous intensity bands resulting fromn= 4 -n= 4 andn= 4 -n= 5 unresolved transition arrays (UTAs) dominate both sets of experimental spectra. Comparison with calculations performed with the Cowan suite of atomic structure codes as well as consideration of previous experimental and theoretical results aided identification of the most prominent features in the spectra. For the 10 ns spectrum, the highest ion stage that could be identified from then= 4 -n= 5 arrays were lower than silver-like Hf25+and Ta26+(which has a 4d104fground configuration) indicating that the plasma temperature attained was too low to produce ions with an outermost 4dsubshell, while for the 170 ps plasmas the presence of significantly higher stages was deduced and lines due to 4d–5ptransitions were clearly evident. Furthermore, we show an enhancement of emission from tantalum using dual laser irradiation, and the effect of pre-pulse durations and delay times between two pulses are demonstrated.Graphical abstract