Development and demonstration of a novel 270-degree bent axial type Electron beam welding machine

Datum objave: 21.07.2011

Kategorija: Aktualno na Univerzi


Partnership request description:  Project Description: In evaporation type electron guns, the electron beam is normally bent by 270-degree by transverse magnetic field (hence called transverse gun) before hitting the target so that vapor and ions do not enter the cathode-anode region of the electron gun causing electrical discharges or instabilities and unwanted coatings. However, in electron beam welding machines, the path of the electron beam is normally designed to be straight so that a highly focused and circularly symmetric beam spot can be generated at the target which is the most important requirement for welding application especially in deep welding cases. As this beam is focused by axial magnetic field, these guns are called axial guns. As the high voltage cathode in these welding guns is placed in the line-of-sight of the welding point, the vapor emitted from the hot zone creates repeated discharges and coating problems. Thus, the important advantage of the transverse gun i.e. non-entry of vapor is sacrificed in case of welding guns to achieve high power density and circular symmetry of the e-beam spot. To circumvent this problem, I have recently evolved a novel scheme for distortion-less bending of a converging non-paraxial electron beam (published in Journal: Nuclear Instruments and Methods in Physics Research A 596, (2008), 300–304). It has been analytically proved that the effect of bending on the size and shape of e-beam spot on the target can be completely eliminated (theoretically made zero) by choosing a radially decreasing magnetic field and a specifically defined circularly asymmetric radial velocity distribution of electrons. However in the paraxial case, distortion-less bending is possible with radially decreasing magnetic field and just a circularly symmetric radial velocity distribution which can be easily generated by a coaxial thin magnetic lens. This analysis is valid for any angle of bending of electron beam and is relativistically correct. Using the above principle, I have proposed and numerically evaluated the performance of a practical 2700 bent-axial-type electron gun used for welding which offers both the advantages: (a) high-voltage cathode assembly placed in a geometrical shadow region of the emerging vapor and (b) compact and circularly symmetric electron beam spot with high power density. These numerical results have been published in the Journal: IEEE Transactions on Electron Devices, 57 (4), (2010), 939-945. Based on this scheme, in this project, I plan to design and experimentally demonstrate the operation of a 2700 bent-axial-type electron-beam welding machine. Due to its compact and circular beam spot, this gun can be useful in deep welding, drilling and high rate PVD from very small targets.
Project proposer:   Biswaranjan Dikshit (India)
Description of the project offered:   Industrial manufacture, Nanotechnology and Nanosciences, Other technology, Measurement method
Partner role:  Project coordinator
Partner organisation:  Research
Call for proposal title:  MARIE CURIE INTERNATIONAL INCOMING FELLOWSHIPS (IIF)
Call for proposal identifier:  FP7-PEOPLE-2011-IIF


Description of the collaboration sought: I need a researcher in EU meber states or associated countries to act as Scientist-in-charge for this project and I will work with him in his institute which will be host institute for me (Marie CurieI IIF). Details of the project is given below. Title of the project: Development and demonstration of a novel 270-degree bent axial type Electron beam welding machine Description: In evaporation type electron guns, the electron beam is normally bent by 270-degree by transverse magnetic field (hence called transverse gun) before hitting the target so that vapor and ions do not enter the cathode-anode region of the electron gun causing electrical discharges or instabilities and unwanted coatings. However, in electron beam welding machines, the path of the electron beam is normally designed to be straight so that a highly focused and circularly symmetric beam spot can be generated at the target which is the most important requirement for welding application especially in deep welding cases. As this beam is focused by axial magnetic field, these guns are called axial guns. As the high voltage cathode in these welding guns is placed in the line-of-sight of the welding point, the vapor emitted from the hot zone creates repeated discharges and coating problems. Thus, the important advantage of the transverse gun i.e. non-entry of vapor is sacrificed in case of welding guns to achieve high power density and circular symmetry of the e-beam spot. To circumvent this problem, I have recently evolved a novel scheme for distortion-less bending of a converging non-paraxial electron beam (published in Journal: Nuclear Instruments and Methods in Physics Research A 596, (2008), 300–304). It has been analytically proved that the effect of bending on the size and shape of e-beam spot on the target can be completely eliminated (theoretically made zero) by choosing a radially decreasing magnetic field and a specifically defined circularly asymmetric radial velocity distribution of electrons. However in the paraxial case, distortion-less bending is possible with radially decreasing magnetic field and just a circularly symmetric radial velocity distribution which can be easily generated by a coaxial thin magnetic lens. This analysis is valid for any angle of bending of electron beam and is relativistically correct. Using the above principle, I have proposed and numerically evaluated the performance of a practical 2700 bent-axial-type electron gun used for welding which offers both the advantages: (a) high-voltage cathode assembly placed in a geometrical shadow region of the emerging vapor and (b) compact and circularly symmetric electron beam spot with high power density. These numerical results have been published in the Journal: IEEE Transactions on Electron Devices, 57 (4), (2010), 939-945. Based on this scheme, in this project, I plan to design and experimentally demonstrate the operation of a 2700 bent-axial-type electron-beam welding machine. Due to its compact and circular beam spot, this gun can be useful in deep welding, drilling and high rate PVD from very small targets.
Expertise sought: Industrial manufacture, Electronics. Microelectronics, Nanotechnology and Nanosciences, Other technology,
Roles sought: Project coordinator, Project participant,
Organisation types sought: Research, Education, Public administration, Technology transfer,
Countries sought: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, United Kingdom, Albania, Bosnia-Herzegovina, Croatia, Iceland, Israel, Liechtenstein, Macedonia, Montenegro, Norway, Serbia, Switzerland, Turkey,