Very high resolution soft x-ray spectrometer for an electron beam ion trap

A very high resolution vacuum flat-crystal spectrometer was constructed for analyzing soft x rays emitted by an electron beam ion trap. The spectrometer was designed to operate at large Bragg angles (theta less than or equal to 85 degrees) in order to maximize the spectral dispersion and thus the resolving power. Using a quartz (100) crystal at a Bragg angle of 82 degrees, a measurement of the 2p(1/2), 2p(3/2) --> 1s(1/2) transitions in hydrogenic Mg11+ situated near 8.42 Angstrom was made. The nominal resolving power of the instrument was better than 30 000 allowing us to infer the ion temperature (246 +/- 20 eV) from the observed line widths. A comparison with an existing flat-crystal spectrometer demonstrates the great improvement in resolving power achieved. (C) 1997 American Institute of Physics.