INVESTIGATION OF PLASMA IN THE ADIABATIC "OGRENOK" TRAP

Journal Article · Mon Jan 01 00:00:00 EST 1962 · Nuclear Fusion, Suppl.

OSTI ID:4808616

Brevnov, N N; Romanovskii, M K; Tomashchuk, Yu F

$ nok is a cylindrical stainless steel vacuum chamber, 2 m long and with a diameter 0.5 m, located in an axially symmetric magnetic field of strength up to 3000 Oe in the center and up to 4500 Oe in the magnetic mirrors. An atomic beam of hydrogen ions with an energy of 10 kev is injected into the central part of the chamber. Two devices for the injection of the beam into the chamber are described, namely a magnetic channel and an electrostatic channel. The conditions of injection and the behavior of the ion beam within the system are investigated for both types of channels. For investigating the fast-ion beam in the magnetic mirror trap (i.e., motion and containment of ions, space charge compensation, interaction of the injected beam with residual gas and cold plasma, etc.) a beam of atomic ions, not molecular ions, is used, since this smalldimensioned system is not capable of transition into residual gas burning- out'' conditions (reaching the turn-over point). Therefore, experiments are done with an atomic-ion beam. The value of the fast-ion density in the trap varies from 10/sup 5/ to 10/sup 7/ ions per cm/sup 3/, depending upon the injected beam current. The zones of the beam reflections from the magnetic mirrors and the angles of the beam drift at the reflection are experimentally determined. The fast-ion density distribution along radius, azimuth, and length of the system is studied. The paths of the fast ions in the trap are determined. It is shown that the fast ions go out into the mirrors earlier than is possible assuming only Coulomb scattering, and it is proved that one of the reasons for fastion escape into the mirrors is the presence of a local nonuniformity of the magnetic field created by the magnetic channel. It is shown that the local perturbation of the magnetic field leads to a displacement of the fast ions across the magnetic field. The escape of slow ions and electrons formed during charge exchange of the fast ions with the residual gas is investigated. The distribution of the slow ions a electrons escaping into the mirrors radially and azimuthally is studied. It is shown that the slow ions escape in the vicinity of the axis of the system. The upper boundary of the slow ions escaping into the mirrors, which is measured by the diaphragm method with a retarding potential, shifts towards lower energies with increasing radius. This behavior indicates that there is a peculiar distribution of the space charge, and consequently that there is incomplete compensation of the injected beam. It is shown that the ratio of the electron current to the slow-ion current near the axis of the system is smaller by at least one order of magnitude than the corresponding ratio when the ions are born in the volume at a given radius. The shape of the distribution curve of the current density for those electrons which escape into the mirrors and the anomalously weak electron current for small radii indicate that the electrons escape quickly across the magnetic field. The character of the ion and electron current distributions for ions and electrons which escape into the mirrors is practically independent of the pressure of the residual gas within the interval from 3 x 10/sup -6/ to 8 x 10/sup -6/ mm Hg. The method of diaphragm probes with retarding potentials yields values averaged in time for the electron and slow-ion currents. By means of oscillographic measurements it is established that there are oscillations of the charged-particle density distribution in the volume. It is shown that in the system there are cold-plasma oscillations with a frequency of 10 kc with 100% modulation and oscillations with frequencies 100to 120kc and to 1.2 Mc with a 10to 15% modulation. Frequencies of 100 kc and more are found in the injected fast-ion beam but the frequency 10 kc is missing. A peculiarity of the oscillations is their phasing-in, for a given radius, on the various azimuths and their phasing-in, for a given azimuth, on the various z-values. This phase behavior indicates a pulsation of the whole volume occupied by

• Research Organization: Kurchatov Inst. of Atomic Energy, Academy of Sciences, Moscow
• NSA Number: NSA-16-023237
• OSTI ID: 4808616
• Journal Information: Nuclear Fusion, Suppl., Other Information: Orig. Receipt Date: 31-DEC-62
• Country of Publication: Country unknown/Code not available
• Language: Russian

Related Subjects

PHYSICS
ATOMS
CHARGED PARTICLES
CONFIGURATION
CONFINEMENT
CURRENTS
CYLINDERS
DENSITY
DISTRIBUTION
DISTURBANCES
ELECTRIC CHARGES
ELECTRIC FIELDS
ELECTRIC POTENTIAL
ELECTRONS
ELECTROSTATICS
ENERGY RANGE
FREQUENCY
GASES
HYDROGEN
INJECTION
INTERACTIONS
ION BEAMS
IONS
KEV RANGE
LOSSES
MAGNETIC FIELDS
MAGNETIC MIRRORS
MEASURED VALUES
MODULATION
MOTION
ORBITS
OSCILLATIONS
OSCILLOGRAPHS
PLASMA
PRESSURE
PROBES
REFLECTION
SCATTERING
SPACE CHARGE
STAINLESS STEELS
THERMONUCLEAR DEVICES
VACUUM
VESSELS