Hot Ring Research Articles

Kernfusion und das Energieproblem

The present understanding of the physics and technology problems of confining a hot plasma ring by magnetic fields and of heating it to such temperatures that thermonuclear fusions between deuterium and tritium nuclei provide the energy required to maintain this temperature seems to allow to predict the possibility of a self-sustaining thermonuclear reactor. Imbedding this chance into world energy scenarios for the next fifty years, it is shown that fusion reactors of a type of which each may supply about ten slow fission reactors with fissionable material may play a critical role by drastically reducing the number of required fast fission breeder reactors.

EBT Ring Physics

The purposes of the workshop were (1) to evaluate the status of the current experimental and theoretical understanding of the hot electron ring properties, (2) to identify the dominant physical processes that influence ring formation and scaling and their optimal behavior, and (3) to determine critical areas for near-term research.

A simulation study of cold electron heating by loss cone instabilities

We present results of a computer simulation study of electron cyclotron harmonic waves. We model the initial electrons velocity distribution function as a hot ring perpendicular to the ambient magnetic field and a cold Maxwellian component. We identify nonlinear cyclotron resonance as the saturation mechanism of the unstable waves and as the heating mechanism of the cold electrons.

A compressional Pc4 pulsation observed by three satellites in geostationary orbit near local midnight

We describe the observation of a magnetic pulsation with a period of 55 s, recorded at geostationary orbit by three satellites (ATS 6, SMS 1 and SMS 2) in the local time sector 2100–2400. We use magnetic data from all three spacecraft and also plasma data from ATS 6. The pulsation had a large compressional magnetic component which appeared to be balanced by pressure fluctuations in the hot ring current plasma which were in antiphase with the magnetic variations. This allows the wave to be guided along a field line. From the plasma data we are also able to obtain estimates of the field line displacement and hence the electric field, which enables us to conclude that this is a second harmonic field line resonance. We find that the wave has a very short East-West (E-W) wavelength (m≅100) and a westward azimuthal group velocity of about 30 km s −1. The most probable source for this wave is a bounce resonant interaction with ring current protons. The characteristics of this wave are in many ways similar to those of giant pulsations observed on the ground. ATS 6 was near the inner edge of the ring current electrons and as the wave converted the 10 keV electron Alfvén layer back and forth across ATS 6, we were able to estimate the Alfvén layer energy gradient and obtain a value of 1 keV in 1000 km. This gradient is considerably steeper than that predicted by a steady uniform convection electric field.

The plasmapause as a plasma sheath: a minimum thickness

We consider the plasmapause as a stationary boundary layer (a sheath) separating two types of plasmas characterized by different temperatures and densities: on one side, the hot trapped particles imbedded in the cold exospheric plasma of ionospheric origin, and on the other side the plasmatrough including the hot ring current particles. The structure of this layer is described by a kinetic model using the Vlasov-Maxwell's equations for the charged particles and fields. In absence of any collisional effects or wave-particle interactions a minimum value for the thickness of the plasmapause is deduced which is of the order of 5 times the Larmor radius of the cold ions.

Plasma and Magnetic Field Characteristics of the Distant Polar Cusp near Local Noon: The Entry Layer

Heos 2 plasma and magnetic field measurements in the distant polar cusp region reveal the existence of a plasma layer on day side field lines just inside the magnetopause. Density and temperature in this layer are nearly the same as they are in the adjacent magnetosheath, but the flow lacks the order existing both in the magnetosheath and in the plasma mantle. Flow directions toward and away from the sun but, in general, parallel to the field lines have been found. The magnetopause (as defined by a sudden rotation of the magnetic field vector) mostly coincides with the transition to ordered magnetosheath flow. The inner boundary of the layer is located just within the outer boundary of the hot ring current plasma. In the region of overlap the hot electrons have the signature of trapped particles, though often at reduced intensity. The magnetic field is strongly fluctuating in magnitude, while its orientation is more stable, consistent with a connection to the earth, but is systematically distorted out of the meridian plane. The layer is thought to be a consequence of the entry of magnetosheath plasma, which does not appear to be unobstructed, as has been claimed in the concept ofmore » a magnetospheric cleft. The magnetopause has a cusplike indentation which is elongated in local time. The existence of field-aligned currents (total strength approx. =10/sup 6/ A) and their location of flow in the inner part of the entry layer (into the ionosphere before noon and out of it after noon) are inferred from the systematic bending of field lines. It is proposed that the dynamo of the related current system is provided by the transfer of perpendicular momentum resulting from the plasma entry into the layer. The essential features of the entry layer might be compatible with the model of plasma flow through the magnetopause of Levy et al. (1964) if a 'dam' effect caused by the cusp geometry were added. (AIP)« less

Interpretation of "Nondivergent Radiation of Discrete Frequencies in Continuous X-Ray Spectrum"

The observation of "hot spots" and "hot rings" in continuous x-ray spectra from targets with cylindrical bores is acknowledged but has a simple explanation. Hot spots appear purely as a result of the geometry of the arrangement; in addition, hot rings are an optical illusion. There is no need to introduce parametric coupling between electron and photon wavelengths and there is no experimental evidence for discrete frequencies in the bremsstrahlung spectrum.

The proton ring current and its interaction with the plasmapause: Storm recovery phase

Using data from the Explorer 45 satellite, we have studied the interaction of the proton ring current with the plasmapause during the December 17, 1971, geomagnetic storm. This study concentrates on the storm recovery phase. The observed spatial, pitch angle, and energy distributions are shown for the near-midnight proton ring current for prestorm quiet, main phase, and recovery phase. Initial measured distribution functions f(υ⊥, υ∥) are also shown. During recovery phase at altitudes just above the plasmapause, ring current protons exhibit a pitch angle distribution that is nearly isotropic except for an empty loss cone. As the plasmapause is approached, this distribution switches rapidly to one that is peaked near α=π/2. We conclude that during recovery phase there exists a region just above the plasmapause in which the hot ring current plasma is stably trapped with negligible losses due to pitch angle scattering. As the plasmapause region is approached, moderate pitch angle diffusion is initiated. The spatial, energy, and time dependence of this process, its analysis via the resonant energy equation, and a comparison with an in situ estimate of the cold plasma density strongly indicate that scattering by ion cyclotron waves is the cause of the pitch angle diffusion. We thus further conclude that amplification of ion cyclotron waves by the interaction of the hot ring current plasma with the cold plasmaspheric plasma in the region of the plasmapause is an important loss process for the ring current particles during storm recovery phase. The energy range over which this process occurs is from ∼1 keV to several hundred keV. Low-altitude observations of low-energy protons through the local loss cone are consistent with and included in this picture of recovery phase processes.

Increasing the toughness and ductility of steel 000Kh11N10M2T in large sections

1. Hot rolled rings manufactured by the full cycle consisting of water quenching from 1200°, rolling at 1050°, hardening from 860°, and aging at 500–525° have a high ductility and toughness in the tangential direction and satisfactory properties in the axial directions. 2. The ductility and toughness of rings manufactured by the shortened cycle without preliminary quenching from 1200° differ little from those of rings quenched from 1200°. However, the fractures of impact test samples have a distinct texture, and therefore the equivalence of these treatments can be confirmed only by additional studies of larger sections. 3. The ductility and toughness of hot rolled rings can be increased by heat treatment to an ultimate strength σb=120−130 kg/mm2, which permits austenite to be retained in the structure: 600° for 2 h or 600° for 5 h+500° for 2 h. 4. It was found that the ductility and toughness of steel 000Kh11N10M2T can be increased by heat treatment to an ultimate strength σb=135−150 kg/mm2, including aging at 600°, hardening from 860°, and aging at 500°.