In-band EUV radiation of ablative capillary discharges in PVC

Abstract

A study of the performance of an ablative capillary discharge through a PVC capillary is reported. It is shown that the PVC capillary is capable of producing strong in-band 13.5 nm EUV radiation. This band of radiation is produced by transition arrays of multiply ionised heavy metal ions (Sn, Zn, etc.) that are constituents of various chemical additives in commercial PVC grades. A low concentration of radiating ions, good thermalisation of the capillary plasma and plasma homogeneity along the capillary axis produce well-defined bands with little line radiation outside the band of interest. Two interesting cases are discussed, both producing band radiation with a full-width at half-maximum of around 1 nm and maxima near 10, 13.5 and 15.5 nm, respectively. The plasma spectra are not very sensitive to input discharge voltage, but in some cases the amount of energy in the band of interest can be controlled by it. The most serious problem of such discharges still remains the amount of macroscopic debris produced by the capillary ablation.