Title

The Role of LLNL's FAST Calibration Facility in Diagnosing NIF Fusion Plasmas

Author Info

Joshua G. Thompson, California Polytechnic State University - San Luis ObispoFollow
Carey Scott, California State University - Chico
Greg V. Brown, Lawrence Livermore National Laboratory

Recommended Citation

August 1, 2011.

Abstract

The Fusion and Astrophysics (FAST) Calibration and Diagnostic Facility uses the original Electron Beam Ion Trap (EBIT-I) to profile x-ray filters that are used in the Dante Soft X-Ray Diagnostic at the National Ignition Facility (NIF). FAST has an advantage over any other facility not only for its high accuracy, but also for its proximity to NIF in the Lawrence Livermore National Laboratory (LLNL). This makes for highly accurate and near-instantaneous filter calibration turnover.

EBIT-I was first constructed to create, trap, and observe static highly charged ions (HCIs) and conduct experimental astrophysics (creating an x-ray spectroscopy catalogue of ions). To do this, EBIT-I uses a super-cooled, super-vacuum chamber which fires an electron beam that strips injected atoms of some to all of their electrons. To trap these new ions, an array of superconducting magnets and high electric potentials contain the HCI’s. A second neutral gas is then injected to encourage the HCI’s to drop in energy levels and emit measurable x-rays using the EBIT Calorimeter Spectrometer (ECS).

However, EBIT-I has proven to be more versatile beyond these investigations of astronomy and nuclear physics. If premeasured HCIs are created inside EBIT-I, FAST can place unknown filters before the ECS and test the transmittance (or the level of x-ray transparency) of the filter material. Transmittance depends only on the wavelength of light and filter thickness, so FAST’s ability to quickly change to different x-ray energies by running different HCIs gives it accuracy and quick run times that no other facility can match.

Disciplines

Atomic, Molecular and Optical Physics | Nuclear | Stars, Interstellar Medium and the Galaxy

Mentor

Greg Brown

Lab site

Lawrence Livermore National Laboratory (LLNL)

Funding Acknowledgement

This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation.