# Abstracts

## XX International Linac Conference

## MOE13 (Poster)

**Presenter: **Christopher Allen (LANL)

** email: **ckallen@lanl.gov

**Status: **Complete

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# Investigation of Halo Formation in Continuous Beams
Using Weighted Polynomial Expansion and Perturbational
Analysis*

Christopher K. Allen (LANL)

Perturbation analysis, along with a weighted polynomial expansion of the
self-fields, is used to construct approximate halo particle trajectories. The
analysis is based on the particle-core model of halo formation. Here, the self-fields
of the core are expanded in a polynomial where the coefficients are chosen to
minimize the least-square error from the true fields. The error is weighted against
the core distribution so that the expanded fields are an laveragedn representation of
the fields felt by halo test particles. Keeping the nonlinear terms in this expansion
retains the stability of the halo particles in the model, which is not possible with
Hillms equation used previously in particle-core studies. From this model, we employ
perturbation analysis to construct approximate solutions for the halo particle
trajectories. These solutions can provide quantitative information on the halo
formation, such as amplitude and time constants, accurate when the relative beam
mismatch is small.

*Work supported by US Department of Energy

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