NDCX-II layout for 23 induction cells.
Pulse length vs . Vertical lines denote acceleration gaps, some of which are numbered.
Pulse duration vs .
Waveforms for acceleration from ASP.
Snapshots from an ASP simulation, showing evolution of kinetic energy and current profiles.
Warp simulations of an injector configuration: (a) as designed using steady-flow “gun” model, showing trajectories (stretched ordinate); (b) snapshot of beam at 700 ns (true aspect ratio) and profiles of current and kinetic energy. Electrodes are: emitter (“e”), extractor (“x”), accel (“a”), and decel (“d”). The “accel-decel” pair provides transverse focusing.
Snapshots from a video sequence generated using Warp in geometry (enhanced online). [URL: http://dx.doi.org/10.1063/1.3292634.1]10.1063/1.3292634.1
Energy deposition into target plane at from Warp in geometry; colorbar denotes ; semiaxes of ellipse equal RMS extents in and .
phase space at target plane from Warp in geometry. Inner line denotes centroid (fluctuations are due to noise); outer lines denote RMS extent, relative to centroid.
Images from a video depicting the beam in a 3D Warp simulation of NDCX-II; colorbars denote ion kinetic energy. The structures immediately adjacent to the beam line denote the volumes occupied by the solenoids and their flux return channels. The induction cores, outboard of the solenoids, are not shown to true scale—their radial extent is compressed by a factor of two, so as to allow the orientation of the induction cells to be seen. The system is assumed perfectly aligned, and the beam is shown (a) emerging from the injector; (b) after gap 8; and (c) passing through gap 16 (enhanced online). [URL: http://dx.doi.org/10.1063/1.3292634.2]10.1063/1.3292634.2
Images from a video depicting the beam in a 3D Warp simulation of NDCX-II; as in Fig. 10, but the system is assumed to be misaligned, with random transverse offsets of solenoid ends up to 2 mm (enhanced online). [URL: http://dx.doi.org/10.1063/1.3292634.3]10.1063/1.3292634.3
Energy fluence at focal plane versus amplitude of random offsets of solenoid ends (flat distribution with maximum shown on abscissa), from ensembles of 3D Warp simulations (without steering dipoles): (a) peak deposition, time integrated; (b) average over circle of 0.1 mm diameter surrounding brightest spot, gated in time to include only central nanosecond around peak.
ASP studies of steering (in an extended version of NDCX-II), showing rms values of (solid lines) and (dashed lines) centroid coordinates vs for head, middle, and tail particles, and the corkscrew amplitude; the results are averages over 20 simulations with differing random offsets of solenoid ends up to 1 mm. Dipole magnets and sensors were placed in every fourth cell, and the penalty function was evaluated at the next sensor downstream from the dipole being varied (a) without steering, (b) with steering optimization that penalizes corkscrew amplitude, (c) with steering optimization that penalizes corkscrew amplitude and beam offset, and constrains dipole fields to less than 100 G.
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