Plasma production and confinement in the Baseball II mirror experiment

Conference · Wed Jan 01 04:00:00 EST 1975

OSTI ID:4185055

Anderson, O A; Birdsall, D H; Damm, C C

The problem of plasma build-up in a steady-state magnetic-mirror field is being explored in the Baseball II experiment. Methods under investigation utilize neutral-beam injection either with or without a target plasma. Results are reported for build-up starting from a high vacuum, without a target. To reduce the likelihood of microinstability, an ion distribution broadened by Coulomb scattering is obtained. With injection at energies less than 2 keV in a high-vacuum environment, the mirror losses were found to substantially exceed charge-exchange losses, indicating a broadened ion distribution. However, the threshold density for ion-cyclotron instability was no higher than in previous experiments that were dominated by charge exchange. The onset of instability is observed to depend on beam geometry, and instability signals are usually absent shortly after beam injection ceases. The spatial and temporal distribution of anomalous losses is related to potential perturbations rotating at frequencies near the ion grad-B drift. Anomalous losses increase rapidly as the injected beam increases limiting the density to 3-5 x 10$sup 9$ cm$sup -3$. A pulsed hydrogen discharge in minimum -B geometry for use as a target plasma was also investigated. Densities of 10$sup 13$ to 10$sup 14$ cm$sup -3$ have been measured in a 5-cm-diameter discharge with electron temperature of 5-15 eV. Calculations show satisfactory hot-plasma build-up with 50-A pulsed injection. (auth)

• Research Organization: Univ. of California, Livermore
• NSA Number: NSA-33-005140
• OSTI ID: 4185055
• Country of Publication: IAEA
• Language: English

Related Subjects

*BASEBALL DEVICES-- PLASMA CONFINEMENT
700101* --Fusion Energy--Plasma Research--Plasma Confinement & Heating
CYCLOTRON INSTABILITY
N70100* --Physics--Controlled Thermonuclear Research-- Confinement & Heating
NEUTRAL ATOM BEAM INJECTION
TARGETS