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Intense nonneutral beam propagation in a periodic solenoidal field using a macroscopic fluid model with zero thermal emittance

Technical Report ·
DOI:https://doi.org/10.2172/304187· OSTI ID:304187
;  [1];  [2]
  1. Princeton Univ., NJ (United States). Princeton Plasma Physics Lab.
  2. Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Science and Fusion Center

A macroscopic fluid model is developed to describe the nonlinear dynamics and collective processes in an intense high-current beam propagating in the z-direction through a periodic focusing solenoidal field B{sub z}(z + S) = B{sub z}(z), where S is the axial periodicity length. The analysis assumes that space-charge effects dominate the effects of thermal beam emittance, Kr{sub b}{sup 2} {much_gt} {epsilon}{sub th}{sup 2}, and is based on the macroscopic moment-Maxwell equations, truncated by neglecting the pressure tensor and higher-order moments. Assuming a thin beam with r{sub b} {much_lt} S, azimuthally symmetric beam equilibria with {partial_derivative}/{partial_derivative}t = 0 = {partial_derivative}/{partial_derivative}{theta} are investigated. To illustrate the considerable flexibility of the macroscopic formalism, assuming (nearly) uniform axial flow velocity V{sub b} over the beam cross section, beam equilibrium properties are calculated for two examples: (a) uniform radial density profile over the interval 0 {le} r < r{sub b}(z), and (b) an infinitesimally thin annular beam centered at r = r{sub b}(z). The analysis generally allows for the azimuthal flow velocity V{sub {theta}b}(r,z) to differ from the Larmor frequency, and the model is used to calculate the (leading-order) correction {delta}V{sub zb}(r,z) to the axial flow velocity for the step-function density profile in case (a) above.

Research Organization:
Princeton Univ., Princeton Plasma Physics Lab., NJ (United States)
Sponsoring Organization:
USDOE Office of Energy Research, Washington, DC (United States); Office of Naval Research, Washington, DC (United States)
DOE Contract Number:
AC02-76CH03073
OSTI ID:
304187
Report Number(s):
PPPL--3254; ON: DE98050119
Country of Publication:
United States
Language:
English