CALCULATION OF ION TRAJECTORIES AND MAGNETIC FIELDS FOR THE MAGNETIC TRAPPING OF HIGH ENERGY PARTICLES
Several thermonuclear research devices generate a hot, dense plasma by the accumulation in a magnetic container of high-energy ions that are injected from outside and trapped there. A particle-trapping method whose prospects seem favorable is that of dissociating diatomic or triatomic molecular ions. The synthesis of magnetic fields with certain desired properties and the calculation of singleparticle trajectories in the fields are discussed. Furthermore, consideration is given to perturbations arising from collective ion effects such as space charge, plasma diamagnetism, and the magnetic field of the input ion beam. A summary is given of these studies. The problem of injection in the plane of symmetry between a pair of magnetic mirror coils is solved by analytical and geometrical techinques. Other injection problems arise for machines with helical ion paths (for instance, DCX-2, where the aim is to minimize the helical pitch angle). Necessary concepts are developed to establish criteria of initial beam divergence and magnetic field homogeneity for maximizing path length. Ion movement in injection-duct fields and precession of the molecular-ion orbit upon reflection from a mirror are discussed. Methods are shown that can be applied to synthesize magnetic fields with a central zone homogeneous to within less than 0.1% over a length of about half the distance between the mirrors. These fields are produced by means of spaced, lumped coils and mirror coils giving mirror ratios from 2 to 5. The scheme requires also a carefully controlled field dip of about 2% at the injection point located between the mirrors and the homogeneous central zone. Under these circumstances, it appears possible to achieve a total path length of at least 80 times the length of the homogeneous zone. The collective phenomenon that might most seriously affect these results is space charge. For its effect to be negligible, it is required that the variation of the electrostatic potential energy along the axis inside of the homogeneous zone be much less than 0.1% of the trapped ion energy. A code for the rapid and accurate computation of magnetic fields is described. It proves to be especially advantageous for determining ion trajectories over extended distances in magnetic fields from arbitrary coil assemblies. (auth)
- Research Organization:
- Oak Ridge National Lab., Tenn.
- NSA Number:
- NSA-16-023232
- OSTI ID:
- 4823092
- Journal Information:
- Nuclear Fusion, Suppl., Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
CHARGED PARTICLES
COILS
CONFIGURATION
CONFINEMENT
CURRENTS
DCX DEVICES
DECOMPOSITION
DIAMAGNETISM
DISTURBANCES
ELECTRIC CHARGES
ELECTRIC POTENTIAL
ENERGY RANGE
INJECTION
ION BEAMS
IONIZATION
IONS
MAGNETIC FIELDS
MAGNETIC MIRRORS
MAGNETISM
MOLECULES
NUMERICALS
ORBITS
PLASMA
PROGRAMMING
SPACE CHARGE
THERMONUCLEAR DEVICES
TRAPS
VARIATIONS