| This dissertation describes a study of nonlinear components of the magnetic fields in CESR near the south interaction point (SIP). The vacuum chamber prevents access by a magnetometer. Instead, tools were developed to use the stored beam as a probe.;The test steers the beam in closed bumps passing through the test region at varying displacements. The beam sees changing dipole and quadrupole components of the off-axis field. The ripple due to the dipole component and the tune shift due to the quadrupole component are both easily measured.;The simplest test region is a single thin element. The bumps may be chosen to intersect this element in concentric circles. Then Fourier decomposition of either the tunes or ripples gives the sextupole and higher field components.;More generally there are several nonlinearities in an extended region. A more complex fit using a greater variety of bumps is required. For this test the bump amplitudes formed a mesh of nested hexagons; four phases of bumps were used.;The effects must be integrated if the nonlinear sources are not thin discrete elements. Lie algebraic methods help if higher order interactions between nonlinear elements are significant. These methods and some results are presented, but not used for the actual measurement.;The test was intended to measure 13 m to either side of the SIP. Most or all nonlinear effects found were produced outside this region, as far as ;The only multipole moments showing a noticeable effect are skew and upright sextupoles and upright octupoles and dodecapoles. None is confined to a single magnet or east/west pair of magnets. The sources are beyond the ends of the CLEO solenoid. A skew octupole or upright decapole may be present. No other components are seen.;A dodecapole moment of about 50... |
