dispersion relations, determining all of the parasitic circuit
Different helix and ion injector configurations have
parameters for inclusion into the WARP code [5],
different initial ion velocities, but care must be taken in
studying the dielectric loading effects around the outside
catching the accelerating waveform into the helix before
any decelerating waveforms are produced at the mouth of
of the helix, further work in the input section to the helix
the helix. Once the accelerating waveform is caught at
(near the injector), and better matching of the helix output
section.
the corresponding spatial position, the ions have some
latitude of allowable "slippage" due to the flat top of the
accelerating field.
Riding the accelerating pulse
After the accelerating pulse established itself, it then
propagated down the length of the helix. Figure 7 shows
the accelerating electric field (Ez) along the centerline of
the helix as the pulse propagated down the helix.
Figure 8a-b: the energy gain plot (a) shows the energy
gain for Neon+(c]U hk[TM2/z[[2bubub[1f]r[fVU[2T]fu[Uehk[/UQlQlql[ub
Figure 7: spatial snapshots and the magnitude of the
electric field in the plane of a longer helix are shown for
63ns, 102ns, and 141ns with v=(1.15%)c.
Ions were injected into the particle simulation code
developed as part of [4] with an initial energy of 1MeV
and an injection time selected in order to catch the end of
the accelerating waveform (18ns in this case) using the
prescription from the previous section. For simplicity the
helix had a constant pitch, so as the ions gained energy
(velocity) they advanced up the accelerating waveform.
However the accelerating waveform had a flat top so this
advancement was ignored. The phase space output of the
ion bunch is shown in Figure 8.
FUTURE WORK
There are several activities planned for the upcoming
year for the detailed 3D EM calculations. These include
varying the helix wire diameter, confirming the analytic