EFFECTS OF FIELD IMPERFECTIONS ON RADIAL STABILITY IN A THREE-SECTOR CYCLOTRON
In a medium-energy, three-sector cyclotron the radial oscillation frequency is close to unity; as a result, the stability of the radial motion is sensitive to relatively small field imperfections of particular types. In the absence of field imperfections, the radial stability limits are defined by the location of the three unstable fixed-point orbits associated with the 3/3 resonance. A theoretical analysis is given which specifies the movement of these fixed-point orbits and the consequent evolution of the radial phase space diagram as a function of the imperfection field strength. Formulae are given for the critical strengths of these perturbations at which complete loss of stability sets in. These results can be used to set tolerances on certain undesirable field harmonics for ary given three-sector magnet geometry. Radial phase plots and fixed point orbits obtained from extensive computer calculations using various kinds of field imperfections are presented and analysed. In most cases the agreement between the theory and the computer data is relatively good. The results also demonstrate that the sensitivity of the radial stability to field imperfections increases rapidly with the amount of spiral in the main three- sector field. (auth)
- Research Organization:
- Michigan State Univ., East Lansing
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-007383
- OSTI ID:
- 4730607
- Journal Information:
- Nucl. Instr. Methods, Vol. Vol: 18, 19; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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