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84. The theory of the high frequency brush discharge.
Abstracts 71--84 18:33 71. The Stellarator Concept. United States. The basic concepts of the controlled thermonuclear program at Project Matterhorn, Princeton University, are discussed. In particular, the theory of confinement of a fully ionized gas in the magnetic configuration of the stellarator is given, the theories of heating are outlined, and the bearing of observational results on these theories is described. Magnetic confinement in the stellarator is based on a strong magnetic field produced by solenoidal coils encircling a toroidal tube. The configuration is characterized by a " r o t a t i o n a l transform ", such that a single line of magnetic force, followed around the system, intersects a cross-sectional plane in points which successively rotate about the magnetic axis. A theorem by Kruskal is used to prove that each line of force in such a system generates a toroidal surface ; ideally the wall is such a surface. A rotational transform may be generated either by a solenoidal field in a twisted, or figure-eight shaped, tube, or by the use of an additional transverse multipolar helical field, with helical symmetry. Plasma confinement in a stellarator is analyzed from both the macroscopic and the microscopic points of view. The macroscopic equations, derived with certain simplifying assumptions, are used to show the existence of an equilibrium situation, and to discuss the limitations on material pressure in these solutions. The single-particle, or microscopic, picture shows that particles moving along the lines of force remain inside the stellarator tube to the same approximation as do the lines of force. Other particles are presumably confined by the action of the radial electric field that may be anticipated. Theory predicts and observation confirms that initial breakdown, complete ionization, and heating of a hydrogen or helium gas to about 106 degrees K are possible by means of a current parallel to the magnetic field (ohmic heating). Flow of impurities from the tube walls into the heated gas, during the discharge, may be sharply reduced by use of an ultra-high vacuum system ; some improvement is also obtained with a divertor, which diverts the outer shell of magnetic flux away from the discharge. Experiments with ohmic heating verify the presence of a hydromagnetic instability predicted by Kruskal for plasma currents greater than a certain critical value and also indicate the presence of other cooperative phenomena. Heating to very much higher temperatures can be achieved by use of a pulsating magnetic field. Heating at the positive-ion cyclotron resonance frequency has been proposed theoretically and confirmed observationally by Stix. In addition, an appreciable energy input to the positive ions should be possible, in principle, if the pulsation period is near the time between ion-ion collisions or the time required for a positive ion to pass through the heating section (magnetic pumping). (Author) Lyman Spitzer, Jr., Physics of Fluids, 1,253-265, July-Aug. 1958. 18
277
emitting substances in gas discharges are obtained by means of thermodynamics. Theoretical analysis is supplemented by means of experimental methods intended for the study of processes at elevated temperatures, such as thermogravimetry and differential thermal analysis. The application of the above permits some insight into the processes of formation, activation, and detrition of electron emitting compositions, guiding the development of a n u m b e r of improved cathodes. (Author) D. M. Speros, J. Electrochem. Soc., 106, 791-799, Sept. 1959. 18 74. Supersonic Motion of Vacuum Spark Plasmas along Magnetic Fields. D. Finkelstein, G. A. Sawyer, and T. F. Stratton, Physics of Fluids, 1, 188-193, May-June 1958. 18 75. Response of Electrostatic Probes to Ionized Gas Flows in a Shock Tube. Letter by Robert G. Jahn and Fred A. Grossee, Physics of Fluids, 2, 469, July-Aug. 1959. 18 76. Absorption of Gases in the Low Pressure Are. E. Ia. Pumper, Soy. Phys. Tech. Phys., 3 : 10 (Transl.), 2088. 18 77. Micro-discharges and Pre-discharge Currents between Metal Electrodes in High Vacuum. L. 1. Pivovar and V. I. Gordienko, Sov. Phys. Tech. Phys., 3 : l0 (Transl.), 2101. 18 78. Automatic Cloud Chamber for Gas Discharge Studies. K. R. Alien and K. Phillips, Rev. Sci. Instrum., 30, 230. 18 79. Design and Performance of a Hot Cathode Magnetically Collimated Arc Discharge Ion Source. Manlio Abele and Wolfgang Mechbach, Rev. Sci. Instrum., 30, 335. 18 80. Cold Cathode Electric Discharge at Low Pressures in a Magnetic Field. G. V. Smirnitskaya and E. M. Reikhrudel, Soy. Phys. Tech. Phys., 4 : 2 (Transl.), 131. 18 81. Anode Region in a Low Pressure Gas Discharge, N. A. Neremina and B. N. Klyarfeld, Sov. Phys. Tech. Phys., 4 : 1 (Transl.), 13. 18 : 17 Thermodynamics of Electrically Conducting Fluids. See Abstract No. 66.
72. Electrical Breakdown between Close Electrodes in Air. Prebreakdown electron current between electrodes" closing at voltages below the minimum which can give breakdown by successive ionization of air molecules has been measured by two different methods. This field emission current varies widely in successive experiments, increasing in general with decreasing voltage, with maximum values of the order of 10 -7 amp. At the small electrode separations characteristic of breakdown at voltages below 300, it is shown that the ions necessary for breakdown come from the anode surface. The n u m b e r of ions in the space at one time is so small that they cannot cooperate to enhance the gross field at the cathode, which is a conclusion having important consequences for the theory of breakdown. L. H. Germer, J. Appl. Phys., 30, 45-51, Jan. 1959.
19 : 51 83. Phase Changes on Reflection from Evaporated Chromium Films. C. Weaver, R. M. Hill, J. E. S. Macleod, J. Opt. Soe. Amer., 49, 992-997, Oct. 1959.
18 73. On the Research and Development of Electron Emitting Substances for Gas Discharges. Criteria for the stability and chemical behavior of electron
19 : 51 84. The Theory of the High Frequency Brush Discharge. R. Grigorovici and G. Crustecu, Optitsu I Spekstroskopiia, VI, 2, Feb. 1959.
19.
Radiation
19 : 51 82. Design of High-Resolution Monochromator for the Vacuum Ultra-violet. An Application of Off-Plane Eagle Mounting. T. Namioka, J. Opt. Soc. Amer., 49, 961-966, Oct. 1959.
277
emitting substances in gas discharges are obtained by means of thermodynamics. Theoretical analysis is supplemented by means of experimental methods intended for the study of processes at elevated temperatures, such as thermogravimetry and differential thermal analysis. The application of the above permits some insight into the processes of formation, activation, and detrition of electron emitting compositions, guiding the development of a n u m b e r of improved cathodes. (Author) D. M. Speros, J. Electrochem. Soc., 106, 791-799, Sept. 1959. 18 74. Supersonic Motion of Vacuum Spark Plasmas along Magnetic Fields. D. Finkelstein, G. A. Sawyer, and T. F. Stratton, Physics of Fluids, 1, 188-193, May-June 1958. 18 75. Response of Electrostatic Probes to Ionized Gas Flows in a Shock Tube. Letter by Robert G. Jahn and Fred A. Grossee, Physics of Fluids, 2, 469, July-Aug. 1959. 18 76. Absorption of Gases in the Low Pressure Are. E. Ia. Pumper, Soy. Phys. Tech. Phys., 3 : 10 (Transl.), 2088. 18 77. Micro-discharges and Pre-discharge Currents between Metal Electrodes in High Vacuum. L. 1. Pivovar and V. I. Gordienko, Sov. Phys. Tech. Phys., 3 : l0 (Transl.), 2101. 18 78. Automatic Cloud Chamber for Gas Discharge Studies. K. R. Alien and K. Phillips, Rev. Sci. Instrum., 30, 230. 18 79. Design and Performance of a Hot Cathode Magnetically Collimated Arc Discharge Ion Source. Manlio Abele and Wolfgang Mechbach, Rev. Sci. Instrum., 30, 335. 18 80. Cold Cathode Electric Discharge at Low Pressures in a Magnetic Field. G. V. Smirnitskaya and E. M. Reikhrudel, Soy. Phys. Tech. Phys., 4 : 2 (Transl.), 131. 18 81. Anode Region in a Low Pressure Gas Discharge, N. A. Neremina and B. N. Klyarfeld, Sov. Phys. Tech. Phys., 4 : 1 (Transl.), 13. 18 : 17 Thermodynamics of Electrically Conducting Fluids. See Abstract No. 66.
72. Electrical Breakdown between Close Electrodes in Air. Prebreakdown electron current between electrodes" closing at voltages below the minimum which can give breakdown by successive ionization of air molecules has been measured by two different methods. This field emission current varies widely in successive experiments, increasing in general with decreasing voltage, with maximum values of the order of 10 -7 amp. At the small electrode separations characteristic of breakdown at voltages below 300, it is shown that the ions necessary for breakdown come from the anode surface. The n u m b e r of ions in the space at one time is so small that they cannot cooperate to enhance the gross field at the cathode, which is a conclusion having important consequences for the theory of breakdown. L. H. Germer, J. Appl. Phys., 30, 45-51, Jan. 1959.
19 : 51 83. Phase Changes on Reflection from Evaporated Chromium Films. C. Weaver, R. M. Hill, J. E. S. Macleod, J. Opt. Soe. Amer., 49, 992-997, Oct. 1959.
18 73. On the Research and Development of Electron Emitting Substances for Gas Discharges. Criteria for the stability and chemical behavior of electron
19 : 51 84. The Theory of the High Frequency Brush Discharge. R. Grigorovici and G. Crustecu, Optitsu I Spekstroskopiia, VI, 2, Feb. 1959.
19.
Radiation
19 : 51 82. Design of High-Resolution Monochromator for the Vacuum Ultra-violet. An Application of Off-Plane Eagle Mounting. T. Namioka, J. Opt. Soc. Amer., 49, 961-966, Oct. 1959.