Soft X-Ray Measurement of the TPE-RX Reversed Field Pinch Plasma Using High Spectral Resolution TES Microcalorimeter

We report the first result of soft X-ray spectroscopy for the Reversed Field Pinch (RFP) plasma in TPERX using a high spectral resolution (FWHM ∼ 50 eV) superconductive transition edge sensor (TES) microcalorimeter. Total 3472 count of X-ray signals were detected in 0.2‐3.0 keV for 210 plasma shots during the flat-top phase (35‐70 ms) after the pile-up rejection. Combined with the 1.3‐8 keV range data with a SiLi detector, we examined the wide band X-ray spectrum of the RFP plasma. The obtained spectrum is dominated by thermal plasma emission in the soft X-ray band ( 5 keV), although at least four different temperature component is required to account for the whole band spectral shape. The average temperature is consistent with the value by the ruby laser Thomson scattering method. The spectrum also indicates that 85% of the flux in 0.7‐1.2 keV is dominated by the Fe-L complex with variously ionized states, and that the iron abundance to deuterium is comparable to the value derived for carbon and oxygen with a VUV spectrometer.