K beta spectra of heliumlike iron from tokomak-fusion-test-reactor plasmas.

Abstract

[ital K][beta] spectra of heliumlike iron, Fe XXV, have been observed from tokamak-fusion-test-reactor (TFTR) plasmas with a high-resolution crystal spectrometer. The wavelength range of the Fe [ital K][beta] spectrum partially overlaps the spectrum of heliumlike nickel (Ni XXVII), which is used on TFTR and the joint European torus for ion-temperature measurements. The experimental arrangement made it possible to observe the Fe XXV [ital K][beta] lines and their satellite transitions of the type 1[ital s]2[ital l][prime]3[ital l][prime][prime][r arrow]1[ital s][sup 2]2[ital l][prime], as well as the entire satellite spectrum of the Ni XXVII [ital K][alpha] line simultaneously. In order to identify the features of the [ital K][beta] spectra and to study their possible interference with the Ni XXVII spectrum, the intensity of the [ital K][beta] spectrum was enhanced by the injection of iron into the plasma. Accurate wavelengths and intensities have been obtained and compared with different theoretical calculations.