Calibration of proton dispersion for the NIF electron positron proton spectrometer (NEPPS) for short-pulse laser experiments on the NIF ARC

Journal Article · 01 October 2018 · Review of Scientific Instruments

DOI: https://doi.org/10.1063/1.5039388 · OSTI ID:1479064

Mariscal, D. ^[1]; Williams, G. J.  ^[1]; Chen, H. ^[1]; Ayers, S.  ^[1]; Lemos, N. ^[1]; Kerr, S. ^[2]; Ma, T. ^[1]

---

1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Alberta, Edmonton, AB (Canada). Dept. of Electrical and Computer Engineering

Experiments using the Advanced Radiographic Capability (ARC) laser at the National Ignition Facility (NIF) aim to characterize short-pulse-driven proton beams for use as both probes and drivers for high-energy-density physics experiments. Measurements of ARC-driven proton beam characteristics, such as energy spectrum and conversion efficiency, rely on the NIF Electron Positron Proton Spectrometer (NEPPS). The NEPPS diagnostic is a version of an existing particle spectrometer which is used for detecting MeV electron and positron spectra via permanent magnetic field dispersion. These spectrometers have not yet been calibrated for protons and instead use an analytical calculation to estimate the dispersion. Small variations in the field uniformity can affect the proton dispersion due to the relatively small resolving power (E/dE) for this diagnostic. A broadband energy, laser-accelerated proton source was produced at the Titan laser to experimentally calibrate the proton dispersion. These experimental data were used to test the theoretical dispersion. Numerical simulations using measurements of the magnetic field variation within the diagnostic were used to obtain a realistic proton dispersion curve for the new NEPPS units. In conclusion, this procedure for obtaining each independent dispersion is applicable to all EPPS and NEPPS diagnostics, given the axial magnetic field profile.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1479064
• Alternate ID(s): OSTI ID: 1478441
• Report Number(s): LLNL-JRNL-751040; 936479
• Journal Information: Review of Scientific Instruments, Vol. 89, Issue 10; ISSN 0034-6748
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English