Search NASA⌕ Search

Engineering topics

Bergeron, J.

Publications and source records attributed to Bergeron, J..

Using additive manufacturing technologies in high-field accelerator magnet coils

Recent advances with additive manufacturing (AM) technologies using various materials allow them to be considered for the manufacture of precise and complicated metal parts of the magnet coils of high field accelerator magnets from aluminum bronze, titanium alloy, stainless steel, etc. The 3D printing technology is also being used to fabricate prototype models of real parts to test and optimize their geometry. This paper discusses the designs of the complex stress-management coil parts developed at Fermilab, their fabrication using AM technologies, and quality control methods and results.

36 MATERIALS SCIENCE↗

The Hubble Space Telescope Quasar Absorption Line Key Project: The Unusual Absorption-Line System in the Spectrum of PG 2302+029--Ejected or Intervening?

We report the discovery of a high-ionization broad absorption line system at a redshift of z(sub abs) = 0.695 in the spectrum of the z(sub em) = 1.052 radio-quiet quasar PG 2302+029. Broad absorption with FWHM from 3000 to 5000 km/s is detected from C iv, N v, and O vi in Hubble Space Telescope (HST) Faint Object Spectrograph spectra of the quasar. A narrow-line system (FWHM approx. 250 km/s) at z(sub abs) = 0.7016 is resolved from the broad blend and includes absorption by Ly alpha and the C iv, N v, and O vi doublets. No absorption by low-ionization metal species (e.g., Si II and Mg II) is detected in the HST or ground-based spectra for either the broad or the narrow system. The centroids of the broad system lines are displaced by approx. 56,000 km/s to the blue of the quasar's broad emission lines. The reddest extent of the broad-line absorption is more than 50,000 km/s from the quasar. The properties of this system are unprecedented, whether it is an intervening or an ejected system.

Jannuzi, B. T.↗

The emission-line spectrum of 3C 48

The spectrum and absolute energy distribution of the quasar 3C 48 are analyzed, yielding the following results. The forbidden lines are blueshifted with respect to the permitted lines by 600 km/s. The Balmer lines can be decomposed into a narrow and a broad component, with the narrow component having the redshift of the forbidden lines. The Mg II profile fits well the broad components of H-beta and H-gamma along with the Fe II profiles, and the forbidden O II profile fits well the profiles of forbidden O III and higher-ionization forbidden lines. The spatial coverage in the broad-line region is large, ranging from 0.1 to 0.4, and the optical depth at the Lyman limit is much greater than unity; the electron density is greater than 10 million per cu cm. The forbidden-line region has a lower density (less than 1 million per cu cm) and is subdivided into a low-excitation (forbidden O II) and high-excitation (forbidden O III) zone. The helium abundance appears to be normal.

Thuan, T. X.↗