INSTABILITY IN LOW-PRESSURE PLASMA DIFFUSION EXPERIMENTS

Journal Article · Mon Jan 01 04:00:00 EST 1962 · Physics of Fluids (U.S.)

OSTI ID:4819361

Guest, G; Simon, A

The diffusion rate across a magnetic field of the ions and electrons in a positive column has revealed the existence of a critical magnetic field for the onset of an anomalous diffusion rate across the magnetic field. It is shown here that an entirely similar mechanism may also be operative in the low-pressure regton and that the instability which results may provide an explanation of various experimental anomalies. A tynical illustration is a line source of plasma located on the central axis of a finite conducting cylindrical shell with an external magnetic field applied parallel to the axis. Plasma diffuses out in the radial direction and streams to the conducting end walls in the z direction. Space charge is maintained, however, by electric fields which adjust the streaming of electrons and ions out of the plasma to the end walls. Thts unequal rate of streaming of ions and electrons in the longitudinal direction provides a mechanism for separating the ion and electron screw perturbations in the Hoh- Lehnert model, thus permitting an instability to occur. From the calculations of this instability, it is found that a critical field is predicted which is directly proportional to the gas pressure, which is in the neighborhood of 2000 gauss for hydrogen gas at a pressure of 10/sup -4/ mm and with the temperature of the ions and electrons equal to 2 ev. The pitch of the unstable mode is always such that j x B points away from the cylindrical axis. In addition the screw rotates about the magnetic field in the same direction as a positive ion tends to rotate and with a frequency of 50,000 cps. (N.W.R.)

• Research Organization: North Texas State Univ., Denton, Tex.
• NSA Number: NSA-16-007213
• OSTI ID: 4819361
• Report Number(s): GA-2707; 0031-9171
• Journal Information: Physics of Fluids (U.S.) , Journal Name: Physics of Fluids (U.S.) Vol. Vol: 5; ISSN PFLDA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CONFIGURATION
CYLINDERS
DIFFUSION
DISTURBANCES
ELECTRIC CHARGES
ELECTRIC CONDUCTIVITY
ELECTRIC FIELDS
ELECTRONS
EV RANGE
FREQUENCY
HYDROGEN
IONS
LOSSES
MAGNETIC FIELDS
PHYSICS
PINCH
PLASMA
POSITIVE COLUMN
PRESSURE
ROTATION
SHELLS
SPACE CHARGE
STABILITY
SURFACES
TEMPERATURE