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Title: CONTROLLED THERMONUCLEAR RESEARCH SEMIANNUAL REPORT, JULY THROUGH DECEMBER 1961

Abstract

8 ? = 9 = ; 8 9 < 9 4 8 9 1 measurements demonstrated that in the 9-inch-bore third stage the plasma responded normally to magnetic compression for the first 90 mu sec of the cycle but drifted radially as a body striking the wall at the end of this period. Neutrons produced during this period were clearly shown to be produced by d-d fusion events in the hot plasma. The side drift of the plasma (approx 2 x 10/sup 5/ cm/sec) was shown to be correlated with asymmetries in the fields produced by the two transfer coils. To remove the asymmetries, a new set of multiturn coils on a 6-inch-bore section was installed in place of the 9-inch-bore system. With the new system the neutron-production time has been extended by a factor of about 2, but still is far short of the 270 mu sec compression time. Diagnostic measurements now indicate erratic radial loss of the plasma without any strong azimuthal consistency. During these experiments the large neutron-production rate has been an invaluable aid in diagnosing the history of the hot plasma. The ALICE facility for injecting a beam of 20-kev neutral atoms into a steady-state mirrormore » field is essentially completed and will be in operation early in the next report period. The ion beam neutralizer, beam tube, and burial chamber for disposal of the unused beam of energetic atoms were assembled and successfully operated with a beam of 70 ma of 20-kev neutral atoms, which is ample for initial plasma buildup experiments. In the Table Top msgnetic mirror compression facility the character of the velocity-space instability previously mentioned was more clearly defined. The critical density at which the instability occurs is lower by at least two orders of msgnitude than that corresponding to the mirror'' instability, which had previously been postulated as the mode of the instability. Radial current and electrostatic probes show that in the unstable mode the plasma usually develops a single radial projection which exhibits charge separation and rotates at speeds of 10/sup 5/ to 10/sup 6/ revolutions/sec. These results suggest the presence of an interchange instability, usually with a single rotating flute. It is also observed that under certain circumstances the plasma is quasi-stable in the sense that the instability does not occur unless it is triggered by any of several different types of disturbances. The detailed structure of the plasma when it becomes unstable and the mechanism and rate of growth of the instability are subjects for further study. Resistive instability calculations resuited in the prediction that within the Astron E layer a B/sub theta / field will be spontaneously generated. What effect if any this process will have on E-layer buildup and stsbility is not clear. It has also been shown that in a beam-plasma column formed by a high-energy electron beam passing through a gas the usual electrostatic two-stream mechanism in a weakly ionized medium is less important than a resistive instability of lower growth rate for which dissipative effects do not suppress collective interaction. Extensive calculations of single-particle injection and confinement in a bumpy torus field were carried out. Particles injected through the split coil of the torus behave qualitatively as originally predicted, brt a more nearly optimum set of injection parameters was determined. Experimental evidence for the drift surface diffusion previously predicted for the motion of particles in a bumpy torus field was obtained by studying the effects of stationary probes on the current of particles escaping through the mirror at one end of a distorted mirror field. Engineering design for the bumpy torus apparatus for injection and trapping of 100-kev electrons is nearing completion, and some components of the apparatus have been constructed. In the ion cyclotron resonance experiment (Hothouse II) the structure of the rotational hydromsgnetic wave was determined in greater detail by the use of a seven-coil magnetic probe allowing observation of the B/sub theta / field component at seven positions simultaneously. The re« less

Publication Date:
Research Org.:
California. Univ., Berkeley. Lawrence Radiation Lab.; California. Univ., Livermore. Lawrence Radiation Lab.
OSTI Identifier:
4782978
Report Number(s):
UCRL-9969
NSA Number:
NSA-16-015723
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-62
Country of Publication:
United States
Language:
English
Subject:
PHYSICS; ALFVEN WAVES; ALICE; ATOMS; BEAMS; CHARGED PARTICLES; COILS; CONFIGURATION; CONFINEMENT; CURRENTS; CYCLOTRON RADIATION; CYLINDERS; DEFORMATION; DENSITY; DEUTERONS; DIFFUSION; DISTURBANCES; ELECTRIC CHARGES; ELECTRIC CONDUCTIVITY; ELECTRIC DISCHARGES; ELECTRIC FIELDS; ELECTROMAGNETIC FIELDS; ELECTRON BEAMS; ELECTRON TUBES; ENERGY RANGE; FLUTE INSTABILITY; FREQUENCY; GASES; INDUCTION; INJECTION; INTERACTIONS; ION BEAMS; IONIZATION; IONS; KEV RANGE; LAYERS; LOSSES; MAGNETIC FIELDS; MAGNETIC MIRRORS; MAGNETOHYDRODYNAMICS; MAGNETRONS; MEASURED VALUES; NEUTRONS; OPERATION; OSCILLATIONS; PLANNING; PLASMA; PLASMA WAVES; POWER; PRESSURE; PROBES; PRODU

Citation Formats

. CONTROLLED THERMONUCLEAR RESEARCH SEMIANNUAL REPORT, JULY THROUGH DECEMBER 1961. United States: N. p., 1962. Web.
. CONTROLLED THERMONUCLEAR RESEARCH SEMIANNUAL REPORT, JULY THROUGH DECEMBER 1961. United States.
. Wed . "CONTROLLED THERMONUCLEAR RESEARCH SEMIANNUAL REPORT, JULY THROUGH DECEMBER 1961". United States.
@article{osti_4782978,
title = {CONTROLLED THERMONUCLEAR RESEARCH SEMIANNUAL REPORT, JULY THROUGH DECEMBER 1961},
author = {},
abstractNote = {8 ? = 9 = ; 8 9 < 9 4 8 9 1 measurements demonstrated that in the 9-inch-bore third stage the plasma responded normally to magnetic compression for the first 90 mu sec of the cycle but drifted radially as a body striking the wall at the end of this period. Neutrons produced during this period were clearly shown to be produced by d-d fusion events in the hot plasma. The side drift of the plasma (approx 2 x 10/sup 5/ cm/sec) was shown to be correlated with asymmetries in the fields produced by the two transfer coils. To remove the asymmetries, a new set of multiturn coils on a 6-inch-bore section was installed in place of the 9-inch-bore system. With the new system the neutron-production time has been extended by a factor of about 2, but still is far short of the 270 mu sec compression time. Diagnostic measurements now indicate erratic radial loss of the plasma without any strong azimuthal consistency. During these experiments the large neutron-production rate has been an invaluable aid in diagnosing the history of the hot plasma. The ALICE facility for injecting a beam of 20-kev neutral atoms into a steady-state mirror field is essentially completed and will be in operation early in the next report period. The ion beam neutralizer, beam tube, and burial chamber for disposal of the unused beam of energetic atoms were assembled and successfully operated with a beam of 70 ma of 20-kev neutral atoms, which is ample for initial plasma buildup experiments. In the Table Top msgnetic mirror compression facility the character of the velocity-space instability previously mentioned was more clearly defined. The critical density at which the instability occurs is lower by at least two orders of msgnitude than that corresponding to the mirror'' instability, which had previously been postulated as the mode of the instability. Radial current and electrostatic probes show that in the unstable mode the plasma usually develops a single radial projection which exhibits charge separation and rotates at speeds of 10/sup 5/ to 10/sup 6/ revolutions/sec. These results suggest the presence of an interchange instability, usually with a single rotating flute. It is also observed that under certain circumstances the plasma is quasi-stable in the sense that the instability does not occur unless it is triggered by any of several different types of disturbances. The detailed structure of the plasma when it becomes unstable and the mechanism and rate of growth of the instability are subjects for further study. Resistive instability calculations resuited in the prediction that within the Astron E layer a B/sub theta / field will be spontaneously generated. What effect if any this process will have on E-layer buildup and stsbility is not clear. It has also been shown that in a beam-plasma column formed by a high-energy electron beam passing through a gas the usual electrostatic two-stream mechanism in a weakly ionized medium is less important than a resistive instability of lower growth rate for which dissipative effects do not suppress collective interaction. Extensive calculations of single-particle injection and confinement in a bumpy torus field were carried out. Particles injected through the split coil of the torus behave qualitatively as originally predicted, brt a more nearly optimum set of injection parameters was determined. Experimental evidence for the drift surface diffusion previously predicted for the motion of particles in a bumpy torus field was obtained by studying the effects of stationary probes on the current of particles escaping through the mirror at one end of a distorted mirror field. Engineering design for the bumpy torus apparatus for injection and trapping of 100-kev electrons is nearing completion, and some components of the apparatus have been constructed. In the ion cyclotron resonance experiment (Hothouse II) the structure of the rotational hydromsgnetic wave was determined in greater detail by the use of a seven-coil magnetic probe allowing observation of the B/sub theta / field component at seven positions simultaneously. The re},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1962},
month = {10}
}

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