Abstract
We developed an echelle spectrometer for the simultaneous observation of the whole visible range with a high instrumental resolution, for example, 0.055 nm (full width at the half maximum) at 400 nm and 0.10 nm at 750 nm. With the spectrometer, the emission from an ablation cloud of an aluminum pellet injected into a high-temperature plasma generated in the Large Helical Device (LHD) was measured. We separated the emission lines into Al I, II, III and IV groups, and estimated the electron temperature and density of the ablation cloud from the line intensity distribution and Stark broadening respectively, of each of the Al I, II and III groups. We also determined the Stark broadening coefficients of many Al II and III lines from the respective Stark widths with the estimated electron temperature and density.
Highlights
A pellet injected into a high-temperature plasma is immediately ablated due to heat flux from the plasma and forms a high-density plasma called an ablation cloud
For the purpose of overcoming this problem, we have developed an echelle spectrometer by ourselves and applied it to study an aluminum pellet ablation cloud generated in the Large Helical Device (LHD) [12]
With developing an echelle spectrometer for the simultaneous measurement of the entire visible region with a high resolution, we observed the emission spectrum of an ablation cloud of an aluminum pellet injected into an LHD plasma
Summary
A pellet injected into a high-temperature plasma is immediately ablated due to heat flux from the plasma and forms a high-density plasma called an ablation cloud. Many atomic and ionic line emissions are observed. Spectroscopic studies of the emissions may offer information about atomic data and possibility of new light sources, and the ablation mechanism and atomic processes therein, and transport in the main plasma. In the Large Helical Device (LHD), for example, pellets of carbon, aluminum, titanium, tin, tungsten bismuth and so on have been injected to examine the dependence of transport coefficients, the emissivity and peak wavelength on the atomic number [1,2,3], owing to its capability to generate stable high-temperature plasmas. Detailed information about atomic processes taking place in the ablation cloud is necessary for more quantitative understanding of the ablation mechanism. Wideband spectra containing many emission lines have been measured for hydrogen, carbon and aluminum pellets [9,10,11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
