Neutron Sciences 2008 Annual Report - 17.79 MB - Spallation ...

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$Powder Diffraction - Spallation Neutron Source$

$Single Crystal Diffraction - Spallation Neutron Source$

70 FACILITY DEVELOPMENT 2008 ANNUAL REPORT Laser Removal of Electrons When the ion beam in the SNS linear accelerator reaches the proton accumulator ring, the negatively charged ions undergo an identity change, becoming positively charged protons. The postage-stamp-size diamond foil that brings about this change has worked well and has lasted longer than a traditional carbon foil likely would. There are concerns with the diamond foil technology, however. The design power of SNS is 1.4 megawatts; at 300 kilowatts the ion beam passing through the diamond foil produced a red glow at an estimated temperature of 2000 degrees. One concern is that a few protons—say, one out of every 10,000—will collide with carbon atoms in the diamond foil, making the surrounding hardware radioactive. Another concern is that the diamond foils could lose integrity when power reaches between 1 and 2 megawatts. Both occurrences could dramatically increase operating costs. In a search for an alternative, Viatcheslav “Slava” Danilov and his accelerator physics team devised a successful laser stripping technology using an Nd:YAG (neodymium-doped yttrium aluminum garnet) lasing crystal. Danilov, who received an award from the European Physical Society for this work, describes this approach as a “paradigm shift.” In the initial experiment, a laser beam with a pulse length of approximately 10 nanoseconds was directed at a negative ion beam, successfully removing electrons from the beam. The next step is to increase the electron-removal efficiency. A larger, more expensive laser system that can operate more effectively for the full pulse length could be needed when the beam power reaches 1.4 megawatts. Nevertheless, laser-stripping technology could be one of the keys to ensuring that SNS can reach its full power potential. Contact: John Galambos (galambosjd@ornl.gov) ORNL NEUTRON SCIENCES neutrons.ornl.gov HFIR’s proposed second cold source. Artist rendition of HFIR’s proposed Neutron Science Center.
2008 ANNUAL REPORT USER PROGRAM ORNL NEUTRON SCIENCES The Next Generation of Materials Research 71 INTRODUCTION
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Page 104 and 105: 102 PUBLICATIONS 2008 ANNUAL REPORT
Page 118 and 119: 116 Units Acronyms and Units 2008 A
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Neutron Sciences 2008 Annual Report - 17.79 MB - Spallation ...

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