5/6/2023 0 Comments Helium electric arc![]() During the ramping-up of current in the main dipole circuit at the nominal rate of 10 A/s, a resistive zone developed leading in less than one second to a resistive voltage of 1 V at 9 kA. A more detailed technical report is available here.ġ. Investigations are continuing and the complete findings will be reported at a later date.Ī - In the following summary, a brief description is given of the chain of events which occurred around mid-day on 19th September. Proper safety procedures were in force, the safety systems performed as expected, and no-one was put at risk.Īfter a period during which the temperature of the magnets in question was allowed to rise close to room temperature, inspections started and a number of clear findings have now been established. On 19 September 2008, during powering tests of the main dipole circuit in Sector 3-4 of the LHC, a fault occurred in the electrical bus connection in the region between a dipole and a quadrupole, resulting in mechanical damage and release of helium from the magnet cold mass into the tunnel. Summary of the analysis of the 19 September 2008 incident at the LHC “This incident was unforeseen,” said CERN Director General Robert Aymar, “but I am now confident that we can make the necessary repairs, ensure that a similar incident can not happen in the future and move forward to achieving our research objectives.” Sufficient spare components are in hand to ensure that the LHC is able to restart in 2009, and measures to prevent a similar incident in the future are being put in place. Proper safety procedures were in force, the safety systems performed as expected, and no one was put at risk. This resulted in mechanical damage and release of helium from the magnet cold mass into the tunnel. ![]() Investigations at CERN 1 following a large helium leak into sector 3-4 of the Large Hadron Collider (LHC) tunnel have confirmed that cause of the incident was a faulty electrical connection between two of the accelerator’s magnets. This resulted in mechanical damage and release of helium from the magnet cold mass into the tunnel.ĭamage of the LHC magnets in sector 3-4 of the LHC, provoked by the incident which happened on 19 September 2008 (Image: CERN) Investigations at CERN following a large helium leak into sector 3-4 of the Large Hadron Collider (LHC) tunnel have confirmed that cause of the incident was a faulty electrical connection between two of the accelerator’s magnets. Different rates of cooling of the shell and the core of the tin particle lead to the formation of a core–shell structure with an amorphous shell and a crystalline core.Geneva, 16 October 2008. The cooling of this material leads to the solidification of the tin and the transformation of the carbon shell. Agglomeration of carbon-tin clusters and coagulation of tin leads to the formation of liquid tin nanoparticles coated with a carbon shell. Cooling the mixture leads to carbon condensation, and then tin condensation begins to occur on the carbon structures. A mixture of carbon and tin vapours formed by electric arc sputtering forms a fan-shaped jet from the interelectrode gap, the temperature of which decreases with the distance from the discharge axis. The collection of material at different distances from the arc discharge allows the identification of the processes leading to the formation of this structure. However, the processes leading to the formation of nanostructures are not fully understood and require additional research. Such a tin material has four times reduced enthalpy of melting due to the presence of an amorphous phase. The tin nanoparticles themselves have a core–shell structure with crystalline core and amorphous shell. ![]() When electric arc sputtering of a composite tin–carbon electrode occurs in an inert gas medium, a material is formed that is composed of spherical tin nanoparticles surrounded by a carbon shell. Electric arc discharge is a straightforward and attractive method for the synthesis of nanomaterials with unique properties.
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