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256:. Unless otherwise indicated, this information has been authored by an employee or employees of the Los Alamos National Security, LLC (LANS), operator of the Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396 with the U.S. Department of Energy. The U.S. Government has rights to use, reproduce, and distribute this information. The public may copy and use this information without charge, provided that this Notice and any statement of authorship are reproduced on all copies
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CCDs (developed jointly by MIT and Los Alamos) at more than two million frames per second. These scintillation cameras are further augmented by a large anti-scatter (“Bucky”) grid to improve image contrast. The unique combination of diagnostics solves technical surveillance problems that have persisted since the
Manhattan Project enabling the United States to assert higher confidence in its nuclear stockpile performance and safety margins without the need for nuclear testing.
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Perhaps the most significant technical advance achieved at the DARHT facility are the high-speed cameras used to image x-rays on the second axis. These cameras utilizes the world's largest LSO crystal array to convert the x-rays into visible light which are then imaged with the world's highest speed
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The second machine (second axis) is more complicated and, when first completed in 2003, was found to be unusable due to electrical breakdown. The origin of the electrical breakdown turned out to be unexpectedly high electric fields between the high-voltage plate and the oil-insulated magnetic cores
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Scientists already knew how to use a short burst (pulse) of high-energy electrons (rather than a continuous beam) to make a short pulse of high-energy x-rays recorded on conventional x-Ray films. The new challenge was for the accelerator to deliver a very large number of electrons in an extremely
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When completed in 1999, the first-axis accelerator produced a 60ns electron pulse with a current of 2 kA and an energy of 20 MeV focused to 1mm diameter spot on the target - the smallest spot size and shortest pulse length ever achieved at that intensity. As a result, image quality was about three
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process in nuclear bombs and/or the effects of severe hydrodynamic stress. The tests are described as "full-scale mockups of the events that trigger the nuclear detonation". The powerful pulsed X-ray beams allow for an ultra-fast motion picture to be constructed showing the details of the process
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Each electron accelerator consists of a long row of doughnut-shaped magnetic induction cells, each connected to a high-voltage generator. There are 74 in total in each accelerator but not all may be used. At the instant of firing, each generator discharges its power, creating a pulse of electric
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Under such extreme implosion forces materials tend to behave like fluids, so this mock implosion is called a hydrodynamic test, or hydrotest. Standard practice is to take a single stop-action snapshot of the weapon mockup's interior as the molten components rush inward at thousands of meters per
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The project became an important priority after the United States stopped testing nuclear weapons in 1992. Approval for an overhaul and new axis came in stages, with the first axis approved for construction in 1992 and the second axis (initially to be a twin of the first) in 1997. This plan was
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An extensive design overhaul and rebuild was required, which was completed in 2008. The project was initially expected to cost $ 30 million in 1988, but costs ultimately rose to $ 350 million by 2008 when the facility became completely operational.
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Planning for DARHT began in the early 1980s. Based upon the success of
Livermore's FXR, induction-linac facility, in 1987 Los Alamos chose the same type of accelerator to replace PHERMEX, an RF accelerator commissioned in 1963.
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current through its induction cell, which in turn creates a large voltage difference across the gap separating that cell from its neighbor. The electron beam-pulse travels through the central bore of the cells, receiving a 200
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Construction was halted between 1995 and 1996 due to lawsuits by Los Alamos Study Group and
Concerned Citizens for Nuclear Safety, two anti-nuclear weapons organizations demanding that the laboratory produce an
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and at sites where metal, high-voltage insulator, and vacuum meet inside the cells. After much analysis, the design error was tracked to faulty equipment used when doing voltage calibrations.
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and wound up into a roll of 20,000 turns to make mammoth six-foot-diameter cores, each four inches wide and weighing more than one and a half tons. Four cores fit into each induction cell.
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being studied in three dimensions. The tests are compared with computer simulations to help improve the accuracy of the computer codes. Such testing falls under the category of
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powerful pulse to generate an x-ray flash that can penetrate the mockup during the ultra-dense implosion. Specifications call for a pulse width of 60 billionths of a second.
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During a weapon's crucial triggering phase, explosive charges that surround the nuclear fuel are detonated at multiple points. The result is a shock wave that moves inward (
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changed when the
Department of Energy decided it wanted the second axis to deliver not one view of the implosion, but a series of views in rapid succession.
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One of the problems was designing the new induction cores to fit in the confines of the previous facility. The design team had to replace the
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machines to record three-dimensional interior images of materials. In most experiments, materials undergo hydrodynamic shock to simulate the
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This article incorporates material from LANL: © Copyright 2010 Los Alamos
National Security, LLC All rights reserved.
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A technician examining one of the refurbished accelerator cells for DARHT's second-axis accelerator.
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for its construction and operation. Activists argued that DARHT is in violation of the
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that can penetrate the heavy metal in a weapon mockup are made with an
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280:"Los Alamos National Laboratory to Begin DARHT 2 Operations"
235:"A New Hydrodynamic Test Facility for Stockpile Stewardship"
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Nuclear weapons infrastructure of the United States
324:DOE Says DARHT Fully Operational; Questions Remain
18:Dual-Axis Radiographic Hydrodynamic Test Facility
156:energy kick each time it passes through a gap.
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265:Fleck, John. "Failure of Axis Plagues Labs",
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76:Nuclear Non-Proliferation Treaty
413:Los Alamos National Laboratory
68:Environmental Impact Statement
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408:Nuclear stockpile stewardship
72:Comprehensive Test Ban Treaty
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94:Description
397:Categories
367:35°50′02″N
241:. May 2007
210:References
116:implosion
42:implosion
308:Archived
130:second.
165:metglas
161:ferrite
53:History
179:Images
134:X-rays
169:mylar
38:X-ray
22:DARHT
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