Variable Radii Bitter Spiral Crystal Spectrometer

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Variable Radii Bitter Spiral Crystal Spectrometer

Princeton Docket #22-3922-1

A novel high-resolution x-ray spectrometer for small or point-like emission sources has been developed using a crystal shape having both a variable major and minor radius of curvature. This variable-radii spiral spectrometer (VR-Spiral) allows five key spectrometer design goals to be achieved simultaneously: 

  1. High spectral (energy) resolution
  2. High throughput
  3. Broad energy range
  4. Reduction of source size broadening 
  5. 1D spatial imaging

This novel shape provides near perfect imaging of a point-source for arbitrarily large crystal dimensions, while also simultaneously minimizing the effect of source size broadening in the case of an extended source. This crystal geometry most closely resembles that of the conventional toroidal crystal while providing significantly improved performance in terms of higher throughput while maintaining exceptionally high energy resolution. In a previous application of the VR-Spiral, the energy resolution of the spectrometer was improved by a factor of five as compared to using a conventional toroidal crystal, going from 15eV (E/𝚫E~900) to 3eV (E/𝚫E~4500) while maintaining the system throughput.


  • Spectroscopy and one-dimensional imaging of small x-ray sources
  • Commercial x-ray spectroscopy and analysis products


  • Greatly improved energy resolution and throughput as compared to any other existing spectrometer geometries
  • Optimized energy resolution at all energies
  • Exceptional performance with any magnification


Dr. Novimir Pablant is a research physicist at the Plasma Physics Laboratory. He received his B.S from the University of California Santa Cruz, and his Ph.D. from the University of California San Diego for optical spectroscopy on the DIII-D tokamak.

Novimir is an internationally recognized expert in x-ray spectroscopy; he has designed novel x-ray spectrometers for major fusion and high energy density physics experiments around the world including: ITER (France), the National Ignition Facility (USA), Wendelstein 7-X (Germany) and the Large Helical Device (Japan). Novimir's primary research interest, beyond diagnostic development, is stellarator energy and impurity confinement.

Intellectual Property Status

Patent pending

Chris Wright

Princeton University Office of Technology Licensing • (609) 258-6762•

Laurie Bagley

Princeton Plasma Physics Laboratory • (609) 243-2425•


Patent Information:
For Information, Contact:
Chris Wright
Head of Technology Transfer
Princeton University
Novimir Pablant
Manfred Bitter
Kenneth Hill
Lan Gao
Frances Kraus
Philip Efthimion