Magnetohydrodynamic (MHD) instabilities in the Berkeley Compact Toroid Experiment (BCTX). BCTX technical report
The Berkeley Compact Toroid Experiment (BCTX) is a device which creates free standing plasma rings known as spheromaks. The spheromak is a magnetic confinement configuration, similar to the tokamak, with both toroidal and poloidal magnetic field components. During creation of the plasma ring, currents flowing in a radial direction in the plasma interact with the toroidal magnetic field to create a force (the J x B force) on the plasma ring. The plasma ring is then accelerated along the length of the gun into a copper cage known as a flux conserver. The flux conserver used in BCTX is of the mesh variety and is in the shape of an oblate spheroid with a diameter of 70 cm. It consists of 5 toroidal and 16 poloidal hoops and is constructed of 0.5-inch copper rods. Magnetic fields in the plasma induce currents in the rods of the flux conserver (called image currents), which in turn set up magnetic fields which help stabilize the plasma. Typical plasma lifetimes are on the order of 100 {mu}s, and plasma temperatures and densities are estimated to be approximately 5 eV and 10{sup 20} m{sup {minus}3} respectively. The authors have measured internal magnetic fields of 1-2 kG, using {dot B} probes. The authors were able to observe the m=1 mode toroidal instability in the plasma rings using the Rogowski coils. They were not able to observe higher order modes because of the limited number of coils and the short lifetime of the plasma. However, since the Rogowski coils do not penetrate the plasma and therefore do not offer significant perturbation in plasma parameters, they hope to be able to use these Rogowski coils (as well as possibly obtaining others) to determine magnetic field amplitudes. This should enable them to eliminate the current magnetic probes which do penetrate the plasma, introducing impurities and perturbing plasma parameters.
- Research Organization:
- California Univ., Berkeley, CA (United States). Berkeley Fusion Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG03-87ER53262
- OSTI ID:
- 10183379
- Report Number(s):
- UCB-BFE-002; ON: DE94019109; TRN: 94:008441
- Resource Relation:
- Other Information: PBD: 24 Jul 1989
- Country of Publication:
- United States
- Language:
- English
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