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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Improvement of Wire-Stretching Technique to the RF Measurements of E-Center and Multipole Field for the Dipole Cavities

After the first publication [1] of wire-stretching technique from its principle to measure the electrical center of a deflecting cavity, more refinements of this techniques including the review of its analytical and simulation results, RF circuit improvement the signal to noise ratio and its application to other cavities have been developed. These applications include the electrical center measurements for the LHC RFD and DQW crabbing cavity prototypes, multi-frequency harmonic kicker cavity for JLEIC electron cooler [2], TE011 cavity developed for the beam magnetization measurement [3], and a separator cavity at BNL [4].

Park, Gunn T.↗
DOE OSTI2017

Improving extraction efficiency of the third integer resonant extraction using higher order multipoles

The new accelerator complex at J-PARC will operate with both high energy and very high intensity proton beams. With a design slow extraction efficiency of greater than 99% this facility will still be depositing significant beam power onto accelerator components [2]. To achieve even higher efficiencies requires some new ideas. The design of the extraction system and the accelerator lattice structure leaves little room for improvement using conventional techniques. In this report we will present one method for improving the slow extraction efficiency at J-PARC by adding duodecapoles or octupoles to the slow extraction system. We will review the theory of resonant extraction, describe simulation methods, and present the results of detailed simulations. From our investigations we find that we can improve extraction efficiency and thereby reduce the level of residual activation in the accelerator components and surrounding shielding.

43 PARTICLE ACCELERATORS↗
NASA NTRS1973

Drift shell splitting by internal geomagnetic multipoles.

Computations on an 80-coefficient model of the earth's field illustrate the 'topography' of the magnetic equatorial surface and the geometry of the drift shells of geomagnetically trapped particles. Individual terms in the spherical harmonic expansion of the geomagnetic scalar potential V(r, theta, phi) are either even or odd in cos theta, where theta = 90 deg denotes the dipole equator. Terms that are even in cos theta tend to 'warp' the equatorial surface, but do not (in first order) distort particle drift shells radially nor split the drift shells of particles having different equatorial pitch angles. Azimuthally asymmetric terms that are odd in cos theta do cause shell splitting in first order. Shell splitting at large L values (neglecting deformation of the earth's field by the solar wind) is found to be dominated by the geomagnetic octupole. At L approximately equal to 1, shell splitting is strongly enhanced by the South American and South African anomalies. When combined with pitch angle diffusion caused by atmospheric scattering, these results may be able to account for anomalous radial diffusion of inner zone electrons.

Roederer, J. G.↗