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Research and production potentialities of electron bombardment evaporation by David Wm. Moore, Servomechanisms, Incorporated, Goleta, California
300
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strutted by Princeton University and the University of Pennsylvania are described and illustrated. The principal component of the vacuum system is the vacuum chamber in which .the protons circulate during the acceleration cycle. The design of the chamber was partly determined by boundary conditions set by the experimental uses of the accelerator, by environmental factors such as high energy nuclear radiation and rapidly varying magnetic fields and by restrictive spatial conditions, as well as by the required operating pressure of 2 x 1OV mm Hg. The unusual features of the resultant solution are detailed. The pumping system, consisting of 24 modular units, and the complement of instrumentation are presented. The control system, which permits remote operation and indication of most of the vacuum system components, is described. The manner in which the vacuum control system interlocks with other accelerator components is discussed. 28. A high pumping rate system at 1O-6 mmHg pressure by W. W. Balwanz, U.S. Naval Research Laboratory, Washington 25, D.C. Studies of the exhaust of chemical rockets at simulated altitudes are now achieved at vacuums down to about one millimeter A material further using conventional pumping techniques. reduction in the ambient pressure, while maintaining the high gas release rate of the rocket exhaust, is impractical with the usual mechanical and diffusion pumps. A study is being conducted to determine the limits of utility of various pumping methods such as, the use of the mass transport energy of the rocket exhaust for compressing the gases, the condensation of gases, the trapping of non-condensables and the use of electrical pumping methods. Preliminary experimental investigations have demonstrated that multifold increases in the pumping rates may be achieved. 29. Sputtering of metals and semiconductors by low energy argon ions by N. Laegreid and G. K. Wehner, Mechanical Division of General Mills, Incorporated, Minneapolis, Minnesota Sputtering yields for polycrystalline semiconductor and metal targets under normally incident A+ ion bombardment were measured in the energy range from 30 to 800 ev. The measurements were made in a low pressure (2-5 micron) high density argon plasma created in a demountable low voltage hot cathode discharge tube. The yields (number of atoms removed/incident ion) were determined by measuring the weight loss of spherical targets immersed like large negative Langmuir probes in the plasma. The yields are independent of gas pressure (below p=30~), ion current density and target temperature. At 100 ev ion energy the yields range from 0.06 atoms/ion for Si to 0.6 atoms/ion for Ag. The curves are discussed in terms of the ion parameters. (This work was supported in part by the Oflice of Naval Research contract.) 30. Evaluation and use of large diffusion pumps and traps for the ultra high vacuum system of the model C-stellarator by W. G. Henderson, G. S. Geiger and J. T. Mark, Radio Corporation of America, Lancaster, Pennsylvania The Radio Corporation of America under contract to Princeton University and the Atomic Energy Commission has conducted engineering investigations in ultra high vacuum to determine the design parameters of large ultra high vacuum pumping systems. In this work many techniques have been developed and much design data has been obtained that will enable engineers designing new systems to approach u.h.v. in a straightforward manner. Following these set rules and techniques, he can be assured of success without the need of experimentation or guess work. This paper described the choice of a pump, the trap, the gauge, how to leak check, bake, when to and how to cool his system, and the do’s and don’ts of maintaining u.h.v. in a continuously pumped system for months on end. 31. Ultra high vacuum systems developments for the model C-stellarator by J. T. Mark and W. G. Henderson, Radio Corporation of America, Lancaster, Pennsylvania
and Symposia The Radio Corporation of America under contract to Princeton University and the Atomic Energy Commission has designed and built the ultra high vacuum system for the first phase of the Model C-Stellarator fusion test bv Princeton University’s Forrestal Laboratories. Many developments resulting from this work are unique and the first of their kind. This paper describes developments of : an eight-inch opening hydraulicly operated and bakeable ultra high vacuum valve, high conductance ultra high vacuum liquid nitrogen traps of very low liquid consumption, large size demountable gold seal joints, four-inch diameter sapphire viewing ports, and many other developments of interest to advancing the science of high vacuum engineering. 32. Research and production potentialities of electron bombardment evaporation by David Wm. Moore, Servomechanisms, Incorporated, Goleta, California The nature of electron bombardment evaporation and its use in both the laboratory and the production line is discussed by this paper. Advantages of electron bombardment heating, including the ability to vaporize practically any material and to do so without contamination, are presented. Practical examples of electron bombardment equipment are illustrated by examples from the research laboratories of the author’s company. Means for supporting the material to be evaporated and for handling non-conductors are discussed as well as methods for controlling the ionization of the gas in the evaporation chamber. The application of electron bombardment evaporation to high quality production is stressed, with particular emphasis on continuous operation and day to day reliability. 33. Electron beams in vacuum processes by E. S. Candidus, M. H. Hablanian, and H. A. Steinherz, NRC Equipment Corporation, Newton Highlands 61, Massachusetts. In recent years several new industrial processes utilizing electron bombardment as the source of heat have been developed. High power electron beams are used for evaporation, melting, joining, refining, and sintering. Each process has characteristic requirements for equipment design. Electron sources, types of electron guns and power supplies, voltage, current and power ranges for the above applications are discussed. Melting, ingot conditioning, and welding of refractory metals are considered in further detail. Technical and economic advantages, performance and operational characteristics of electron bombardment processes are described. 34. A new electron gun for the vacuum evaporation of metals and dielectrics by R. Thun and J. B. Ramsey, U.S. Army Engineer Research and Development Laboratories, Fort Belvoir, Virginia The production of complex film elements in narrow tolerances requires a better control of the deposition parameters and a lower impurity level than presently obtainable. The use of electron guns as evaporation sources promises a reduction of the sample contamination and an accurate control of the deposition rate. A new electron gun is described which focusses the electron beam by a spherical field between cathode and anode. The advantages of such a design over a conventional gun with grid cylinder are greater ruggedness and simplicity, higher energy output and the possibility of a full analytical treatment of its The evaporation of difficult materials such as characteristic. silicon is possible. 35. Adsorption of gases on mercury at 77°K by G. E. Becker, Bell Telephone Laboratories, Murray Hill, New Jersey A study has been made of the adsorption of gases on freshly condensing mercury in a cold trap used with a mercury diffusion The object was to determine the contribution of this pump. process to the pumping speed of the pump-trap combination in the pressure range below 1 x 10eB mm of Hg. It has been found that adsorption in the cold trap makes no significant contribution to the pumping speed for molecular HZ, O,, N,, and CO. An approximate upper limit of 1 x lo-+ may be placed on
Conferences
strutted by Princeton University and the University of Pennsylvania are described and illustrated. The principal component of the vacuum system is the vacuum chamber in which .the protons circulate during the acceleration cycle. The design of the chamber was partly determined by boundary conditions set by the experimental uses of the accelerator, by environmental factors such as high energy nuclear radiation and rapidly varying magnetic fields and by restrictive spatial conditions, as well as by the required operating pressure of 2 x 1OV mm Hg. The unusual features of the resultant solution are detailed. The pumping system, consisting of 24 modular units, and the complement of instrumentation are presented. The control system, which permits remote operation and indication of most of the vacuum system components, is described. The manner in which the vacuum control system interlocks with other accelerator components is discussed. 28. A high pumping rate system at 1O-6 mmHg pressure by W. W. Balwanz, U.S. Naval Research Laboratory, Washington 25, D.C. Studies of the exhaust of chemical rockets at simulated altitudes are now achieved at vacuums down to about one millimeter A material further using conventional pumping techniques. reduction in the ambient pressure, while maintaining the high gas release rate of the rocket exhaust, is impractical with the usual mechanical and diffusion pumps. A study is being conducted to determine the limits of utility of various pumping methods such as, the use of the mass transport energy of the rocket exhaust for compressing the gases, the condensation of gases, the trapping of non-condensables and the use of electrical pumping methods. Preliminary experimental investigations have demonstrated that multifold increases in the pumping rates may be achieved. 29. Sputtering of metals and semiconductors by low energy argon ions by N. Laegreid and G. K. Wehner, Mechanical Division of General Mills, Incorporated, Minneapolis, Minnesota Sputtering yields for polycrystalline semiconductor and metal targets under normally incident A+ ion bombardment were measured in the energy range from 30 to 800 ev. The measurements were made in a low pressure (2-5 micron) high density argon plasma created in a demountable low voltage hot cathode discharge tube. The yields (number of atoms removed/incident ion) were determined by measuring the weight loss of spherical targets immersed like large negative Langmuir probes in the plasma. The yields are independent of gas pressure (below p=30~), ion current density and target temperature. At 100 ev ion energy the yields range from 0.06 atoms/ion for Si to 0.6 atoms/ion for Ag. The curves are discussed in terms of the ion parameters. (This work was supported in part by the Oflice of Naval Research contract.) 30. Evaluation and use of large diffusion pumps and traps for the ultra high vacuum system of the model C-stellarator by W. G. Henderson, G. S. Geiger and J. T. Mark, Radio Corporation of America, Lancaster, Pennsylvania The Radio Corporation of America under contract to Princeton University and the Atomic Energy Commission has conducted engineering investigations in ultra high vacuum to determine the design parameters of large ultra high vacuum pumping systems. In this work many techniques have been developed and much design data has been obtained that will enable engineers designing new systems to approach u.h.v. in a straightforward manner. Following these set rules and techniques, he can be assured of success without the need of experimentation or guess work. This paper described the choice of a pump, the trap, the gauge, how to leak check, bake, when to and how to cool his system, and the do’s and don’ts of maintaining u.h.v. in a continuously pumped system for months on end. 31. Ultra high vacuum systems developments for the model C-stellarator by J. T. Mark and W. G. Henderson, Radio Corporation of America, Lancaster, Pennsylvania
and Symposia The Radio Corporation of America under contract to Princeton University and the Atomic Energy Commission has designed and built the ultra high vacuum system for the first phase of the Model C-Stellarator fusion test bv Princeton University’s Forrestal Laboratories. Many developments resulting from this work are unique and the first of their kind. This paper describes developments of : an eight-inch opening hydraulicly operated and bakeable ultra high vacuum valve, high conductance ultra high vacuum liquid nitrogen traps of very low liquid consumption, large size demountable gold seal joints, four-inch diameter sapphire viewing ports, and many other developments of interest to advancing the science of high vacuum engineering. 32. Research and production potentialities of electron bombardment evaporation by David Wm. Moore, Servomechanisms, Incorporated, Goleta, California The nature of electron bombardment evaporation and its use in both the laboratory and the production line is discussed by this paper. Advantages of electron bombardment heating, including the ability to vaporize practically any material and to do so without contamination, are presented. Practical examples of electron bombardment equipment are illustrated by examples from the research laboratories of the author’s company. Means for supporting the material to be evaporated and for handling non-conductors are discussed as well as methods for controlling the ionization of the gas in the evaporation chamber. The application of electron bombardment evaporation to high quality production is stressed, with particular emphasis on continuous operation and day to day reliability. 33. Electron beams in vacuum processes by E. S. Candidus, M. H. Hablanian, and H. A. Steinherz, NRC Equipment Corporation, Newton Highlands 61, Massachusetts. In recent years several new industrial processes utilizing electron bombardment as the source of heat have been developed. High power electron beams are used for evaporation, melting, joining, refining, and sintering. Each process has characteristic requirements for equipment design. Electron sources, types of electron guns and power supplies, voltage, current and power ranges for the above applications are discussed. Melting, ingot conditioning, and welding of refractory metals are considered in further detail. Technical and economic advantages, performance and operational characteristics of electron bombardment processes are described. 34. A new electron gun for the vacuum evaporation of metals and dielectrics by R. Thun and J. B. Ramsey, U.S. Army Engineer Research and Development Laboratories, Fort Belvoir, Virginia The production of complex film elements in narrow tolerances requires a better control of the deposition parameters and a lower impurity level than presently obtainable. The use of electron guns as evaporation sources promises a reduction of the sample contamination and an accurate control of the deposition rate. A new electron gun is described which focusses the electron beam by a spherical field between cathode and anode. The advantages of such a design over a conventional gun with grid cylinder are greater ruggedness and simplicity, higher energy output and the possibility of a full analytical treatment of its The evaporation of difficult materials such as characteristic. silicon is possible. 35. Adsorption of gases on mercury at 77°K by G. E. Becker, Bell Telephone Laboratories, Murray Hill, New Jersey A study has been made of the adsorption of gases on freshly condensing mercury in a cold trap used with a mercury diffusion The object was to determine the contribution of this pump. process to the pumping speed of the pump-trap combination in the pressure range below 1 x 10eB mm of Hg. It has been found that adsorption in the cold trap makes no significant contribution to the pumping speed for molecular HZ, O,, N,, and CO. An approximate upper limit of 1 x lo-+ may be placed on