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Correction coil for random magnetic field errors in a superconducting storage accelerator

Description: Some considerations are given on the relative size of the random nonlinear field errors in the magnets of a superconducting storage accelerator and of a conventional warm accelerator. A possible correction coil is presented for the random field errors in the magnets of a superconducting storage accelerator. This correction coil consists of 24 conductors spaced equally around a circle, 12 of which can be independently excited. Each conductor can carry a maximum current of 1000 A, and has the dimensions of 0.32 x 0.008 in. for a 40-kG magnet with a 4-in. aperture. (auth)
Date: November 12, 1973
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Multi-layer universal correction magnet

Description: This paper presents an approach for constructing a universal correction magnet in which the return currents play an active role in determining the field. The return currents are not hidden by the iron shield. The coil is wound in many layers, instead of just one layer. Each layer has a particular symmetry, and generates a particular class of field multipoles such that the location of the return current for each independently excited current block is clear. Three layers may be sufficient in many cases. This approach is applied to the ISABELLE storage accelerator correction system.
Date: August 1, 1981
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Nonlinear chromatic effects in the beta function

Description: A theory is presented for computing the nonlinear dependence of the ..beta..-functions on momentum. Results are found for the quadratic term. The results of the theory are compared with computed results. A procedure is proposed for computing the strengths of the sextupole correctors to correct the dependence of the ..beta..-function on momentum.
Date: January 1, 1983
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Strong intrabeam scattering in heavy ion and proton beams

Description: Intrabeam scattering is the scattering of the particles in the beam from each other through the Coulomb forces that act between each pair of particles. This causes the beam dimensions to grow both longitudinally and transversely. In strong intrabeam scattering, the beam dimensions may grow by several fold, and the accelerator aperture is large enough to contain the beam as it grows. The growth rates may be very large initially, but they quickly decrease as the beam increases in size. The growth of a beam of particles has been studied over long periods of time of the order of many hours, for a beam of gold ions and for a beam of protons, and as function of the beam energy. These studies revealed certain features of strong intrabeam scattering which are likely to have a general validity. Some simple general results were found to hold in the high energy limit which hold for ..gamma.. sufficiently above the transition energy, ..gamma..t. One result is the time invariant. (X/sub p/sigma/sub p/)/sup 2/ - sigma/sub x//sup 2/ = constant, where sigma/sub x/ is the rms betatron oscillation amplitude, sigma/sub p/ is the rms relative momentum, ..delta..p/p, and X/sub p/ is the horizontal dispersion. 6 refs., 6 figs.
Date: January 1, 1985
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Correction of the closed orbit and vertical dispersion and the tuning and field correction system in ISABELLE

Description: Each ring in ISABELLE will have 10 separately powered systematic field correction coils to make required corrections which are the same in corresponding magnets around the ring. These corrections include changing the ..nu..-value, shaping the working line in ..nu..-space, correction of field errors due to iron saturation effects, the conductor arrangements, the construction of the coil ends, diamagnetic effects in the superconductor and to rate-dependent induced currents. The twelve insertion quadrupoles in the insertion surrounding each crossing point will each have a quadrupole trim coil. The closed orbit will be controlled by a system of 84 horizontal dipole coils and 90 vertical dipole coils in each ring, each coil being separately powered. This system of dipole coils will also be used to correct the vertical dispersion at the crossing points. Two families of skew quadrupoles per ring will be provided for correction of the coupling between the horizontal and vertical motions. Although there will be 258 separately powered correction coils in each ring.
Date: January 1, 1979
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Stop bandwidths of nonlinear beam-beam resonances

Description: A general expression is given for the stop bandwidths, ..delta nu../sub N/, of nonlinear beam-beam resonances, which is expanded in powers of Y(s), the vertical beam orbit, and which is valid under certain assumptions regarding the orbits and charge distributions near the interaction regions. This result is applied to obtain results for the rms ..delta nu../sub N/ due to random vertical orbit errors, and due to random errors in ..beta../sub y/ at the crossing points. Numerical results are given for the ISABELLE storage accelerator.
Date: December 8, 1979
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Intrinsic and resonance space charge limits

Description: The space charge limit in circular proton accelerators has been studied using a simulation program described below. Results from the simulation study indicate a different model for the space charge limit than the often presented models which emphasize resonances due to magnetic field errors. This simulation study suggests that the intrinsic space charge limit plays an important role. The intrinsic space charge limit is the space charge limit, in the absence of magnetic field errors, and is due to the forces generated by the beam itself. In studies of three operating accelerators, which include the AGS, the PS Booster and the Fermilab booster, it was found that the computed intrinsic space charge limit was fairly close to the experimentally observed space charge limit. This result plus studies of the effects of resonances due to magnetic field errors suggest that the intrinsic space charge limit provides an upper bound for the space charge limit which is not far from what is actually achieved by operating accelerators. The resonances present due to magnetic field errors, if strong enough, can prevent the accelerator from achieving the intrinsic space charge limit. However, the effects of these resonances were found to be appreciable only when the beam intensity gets close to the intrinsic space charge limit. Well below the intrinsic space charge limit, there is little beam growth due to magnetic field error driven resonances, and the space charge forces tend to stabilize these resonances. 4 refs., 5 figs.
Date: January 1, 1989
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Non-linear variation of the beta function with momentum

Description: A theory is presented for computing the non-linear dependence of the ..beta..-functions on momentum. Results are found for the quadratic term. The results of the theory are compared with computed results. A procedure is proposed for computing the strengths of the sextupole correctors to correct the dependence of the ..beta..-function on momentum.
Date: July 1, 1983
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Aperture limits due to the presence of higher-magnetic-field multipoles

Description: Superconducting magnets tend to produce magnetic fields which have larger higher systematic multipoles and larger random multipoles than conventional magnets. In superconducting magnets the magnetic field shape is determined by the current distribution rather than the shape of an iron surface. Higher systematic magnetic field multipoles are then generated by necessary deviations of the current distribution from the ideal desired distribution; random multipoles are generated by errors in the location of the current carrying conductors. The presence of these undesired field multipoles will limit the good field aperture of the accelerator. One effect of these multipoles is that they will distort the working line, the dependencies of the nu-values, nu/sub x/, nu/sub y/, on the momentum ..delta..p/p. Another effect of these multiples is to produce linear and non-linear stop bands. This paper is concerned primarily with aperture limits due to distortion of the working line. For the systematic field multipoles in the CBA, the distortion of the working line leads to a set of allowed values or tolerances for these higher systematic multiples. For the higher random field multiples, the distortion of the working line limits the good field aperature in the CBA at about the momentum spread of ..delta..p/p = +- .014, where ..delta..p/p = +- .01 is required for CBA operation.
Date: January 1, 1983
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department