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Thermal Stress Analyses for a Multislug Beam NLC Positron Target(LCC-0090)

Technical Report ·
DOI:https://doi.org/10.2172/826494· OSTI ID:826494
The power deposition of an incident multislug electron beam in a tungsten-rhenium target and the resultant thermal shock stresses in the material have been modeled with a transient, dynamic, structural response finite element code. The Next Linear Collider electron beam is assumed split into two parts, with each part impinging on a 4 radiation lengths thick target. Two targets are required to avoid excessive thermal stresses in the targets. Each of the two beam parts is assumed broken up into four slugs, each two microseconds apart. Energy deposition from each slug occurs over 265 nanoseconds and results in heating of the target and pressure pulses straining the material. The rapid power deposition of the electron beam and the resultant temperature profile in the target generates stress and pressure waves in the material that are considerably larger than those calculated by a static analysis. The 6.22 GeV electron beam has a spot radius size of 1.6 mm and results in a maximum temperature jump of 438 C. Stress pressure pulses are induced in the material from the rapid thermal expansion of the hotter material with peak effective stresses reaching 78 ksi (5.3 x 10{sup 8} Pa) on the back side of the target, which is less than one half of the yield strength of the tungsten/rhenium alloy and below the material fatigue limit.
Research Organization:
Stanford Linear Accelerator Center, Menlo Park, CA (US)
Sponsoring Organization:
USDOE Office of Science (US)
DOE Contract Number:
AC03-76SF00515;
OSTI ID:
826494
Report Number(s):
SLAC-TN-03-042
Country of Publication:
United States
Language:
English