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Title: Dissimilar Material Welding with High Pulse Repetition Rate Femtosecond Fiber Laser

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PolarOnyx, Inc.
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Resource Type:
Technical Report
Country of Publication:
United States

Citation Formats

Liu, Jian. Dissimilar Material Welding with High Pulse Repetition Rate Femtosecond Fiber Laser. United States: N. p., 2014. Web.
Liu, Jian. Dissimilar Material Welding with High Pulse Repetition Rate Femtosecond Fiber Laser. United States.
Liu, Jian. Thu . "Dissimilar Material Welding with High Pulse Repetition Rate Femtosecond Fiber Laser". United States. doi:.
title = {Dissimilar Material Welding with High Pulse Repetition Rate Femtosecond Fiber Laser},
author = {Liu, Jian},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Aug 21 00:00:00 EDT 2014},
month = {Thu Aug 21 00:00:00 EDT 2014}

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  • A high-repetition-rate femotosecond dye amplifier is demonstrated using a laser-diode-pumped Q-switched Nd:YAG laser. Amplification of wavelength-tunable 300-fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.
  • For the first time femtosecond-laser writing has inscribed low-loss optical waveguides in Schott BK7 glass, a commercially important type of borosilicate widely used in optical applications. The use of a variable repetition rate laser enabled the identification of a narrow processing window at 1 MHz repetition rate with optimal waveguides exhibiting propagation losses of 0.3 dB/cm and efficient mode matching to standard optical fibers at a 1550 nm wavelength. The waveguides were characterized by complementary phase contrast and optical transmission microscopy, identifying a micrometer-sized guiding region within a larger complex structure of both positive and negative refractive index variations.
  • The proposed MiniBooNE experiment requires pulses of 8 GeV beam from the Fermilab Booster at an average repetition rate of 5 Hz and expects to run simultaneously with both Tevatron Collider and NUMI experiment operation. NUMI and antiproton production for the Tevatron Collider together require Booster beam on six consecutive 15 Hz cycles each 1.867 seconds (i.e. every twenty-eight 15 Hz cycles). In this same interval, nine to ten beam pulses are necessary to satisfy MiniBooNE. Booster is therefore expected to accelerate beam on sixteen of every twenty-eight 15 Hz cycles, corresponding to average beam pulse operation of 8.6 Hz.more » The Booster cycle rate is nominally 15 Hz although not all Booster equipment is capable of pulsing continuously at that rate. The Booster gradient magnets are cycled continuously at 15 Hz, but the RF systems and pulsed injection and extraction devices are not. These devices are triggered on each beam cycle and on one or two 15 Hz cycles immediately prior to each beam cycle (or burst of 15 Hz beam cycles). This pre-pulsing is done to establish a fresh charge on energy storage elements in the power supplies and to reset remnant fields in preparation for beam. The pre-pulses result in an average pulse repetition rate for the power equipment somewhat higher than that of the beam. A high pulse repetition rate test of all Booster systems was conducted on March 29, 1998, to identify equipment in need of modification, upgrade, or replacement in order to satisfy the expectations identified above. In general, Booster beam was not run during these tests. The procedure and results of the tests are described in this note.« less
  • The 593/sup 0/C (1100/sup 0/F) stress rupture behavior of similar metal welds (SMWs) and dissimilar metal welds (DMWs) was investigated under cyclic load and cyclic temperature conditions to provide insight into the question, ''Why do DMWs fail sooner than SMWs in the fossil fuel boilers.'' The weld joints of interest were an all ferritic steel SMW made by fusion welding 2-1/4Cr-1Mo to 2-1/4Cr-1Mo using 2-1/4Cr-1Mo filler metal and an austenitic to ferritic steel DMW made by fusion welding Alloy-800H to 2-1/4Cr-1Mo using a nickel base filler metal ERNiCr-3. The stress rupture behavior obtained on cross weld specimens was similar formore » both types of welds with only a 20% reduction in rupture life for the DMW. For rupture times less than 1500 hours, failures occurred in the 2-1/4Cr-1Mo base metal whereas, for rupture times greater than 1500 hours, failures occurred in the 2-1/4Cr-1Mo heat affected zone (HAZ). The HAZ failures exhibited a more brittle appearance than the base metal failures for both types of welds and it appears that the life of both joints was limited by the stress rupture properties of the HAZ. These results support the hypothesis that increased residual stresses due to abrupt changes in hardness (strength) of metals involved are the major contributors to the reduction in life of DMWs as compared to SMWs. 10 refs., 15 figs., 7 tabs.« less