Scientists from Lawrence Livermore National Laboratory (LLNL) cooperated with Princeton Plasma Physics Laboratory (PPPL) to design a new type of X-ray crystal spectrometer, which can measure a challenging feature of high energy density (HED) substances produced in the experiment of National Ignition Facility (NIF) with high resolution.

This work is introduced in a paper in Scientific Instrument Review, which describes a new crystal shape made for the world's most powerful laser NIF. The high energy density plasma produced by laser, similar to the plasma found in star cores, nuclear explosions and giant planets, may be the most extreme state of matter created on earth.

PPPL previously built a spectrometer for NIF, which was delivered in 20 17, providing high-resolution measurement of temperature and density of NIF extreme plasma for inertial confinement fusion experiments. The data obtained are presented in invited lectures and peer-reviewed publications.

These instruments measure the profiles of key parameters, such as the ion and electron temperatures of a large number of thermal masses, which are magnetically confined in the annular tokamak nuclear fusion device to promote the nuclear fusion reaction. In contrast, HED plasma produced by NIF laser is a tiny point substance, which needs different designed spectrometers for high resolution research.

The spectrometer detects copper and tantalum, and now it also detects lead EXAFS. From copper to tantalum to lead, the energy of X-ray is getting higher and higher, and the signal-to-noise ratio is getting lower and lower, which requires optimizing the design of spectrometer. This cooperation will be transferred to NIF in June+10, 5438, when the new crystal will be arranged for testing there, and researchers in both laboratories are eagerly waiting for the results.

Schneider said: "In the experiment of measuring EXFAS spectrum at NIF high X-ray energy, the signal is very low." "The spectrometer design described in this paper focuses on low signals, which improves the signal-to-noise ratio and maintains the high resolution required for observing EXAFS. Different from the commonly used spherical, cylindrical or annular curved crystals, this new crystal follows a sinusoidal spiral shape, so the novel design makes it possible to meet the strict requirements of EXAFS measurement to detect the thermal state of highly compressed high Z materials. "