EBCO TECHNOLOGIES TR CYCLOTRONS, DYNAMICS, EQUIPMENT, AND
APPLICATIONS
RR Johnsona,b, KL Erdmana, Wm. Gylesa, J. Burbeea, E. VanLierb, M. Kovacsa, F. Perronc
a) Ebco Technolgies, Canada, b) Univ British Columbia, Canada, c) Univ.Sherbrooke, Canada
Abstract
The Ebco Technologies TR cyclotrons have a
common parent in the 500 MeV negative ion
cyclotron at TRIUMF in Vancouver. As such,
the TR cyclotrons have features that can be
adapted for specific application. The cyclotron
design is modularized into ion source and
injection system, central region and then
extraction.
The cyclotron ion source is
configured for cyclotron beam currents ranging
from 50 microAmps to 2 milliAmps. The
injection line can be operated in either
continuous (CW) or in pulsed mode. The center
region of the cyclotron is configured to match
the ion source configuration. The extracted
beams are directed either to a local target station
or to beam lines and thence to target stations.
There has been development both in solid, liquid
and gas targets. There has been development in
radioisotope handling techniques, target material
recovery and radiochemical synthesis.
(RF) phase acceptance characteristics
influence on beam quality is reported in
section 4. A very bright beam produces an
intense power density when stopped in a
production target and these characteristics
are described for TRPet cyclotron energies
in section 5. Medical isotope production
techniques use rare gases and work on the
recovery of these gases is reported in section
6.
1. General TR Cyclotron Features
The TR series of cyclotrons has been based
on the design and experience from the
TRIUMF 500 MeV accelerator based in
Vancouver Canada. Ebco is indebted to
TRIUMF for the transfer of the original
designs and some of the original developers
of this accelerator to Ebco.
This
technological transfer has resulted in a small
cyclotron configuration that can be modified
for particular applications. Key design
elements that allow this flexibility are the
external ion source and external targets.
Figure 1 shows the conceptual outline of a
TRPet cyclotron and indicates the steps that
can be taken to tailor the accelerator for a
particular application.
Introduction
The TR series of cyclotrons is based on two
magnet platforms that are capable of
accelerating protons to 19 or 30 MeV. This
report presents the general features of the
TR cyclotrons and indicates that it may be
configured for specific applications in
section 1. Section 2 details pulsed beam
development for pulsed neutron generation.
The insight from this development can be
directed to other applications such as the
TR30 injection line as described in section
3.
The TR cyclotron operational
characteristics influence the overall beam
quality. In particular, the radio frequency
CP680, Application of Accelerators in Research and Industry: 17th Int'l. Conference, edited by J. L. Duggan and I. L. Morgan
© 2003 American Institute of Physics 0-7354-0149-7/03/$20.00
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Figure 1. TRPet Cyclotron
General configuration. Energy is
selected by positioning the extractor.
The targets are external and the beam
ion source is external. The cyclotron
can be used for different applications
by changing these elements.
generate neutron bursts for a neutron time of
flight apparatus. The first configuration that
was examined is shown in figure 2. The
TR30 ion source was converted to deuteron
operation and the injection system
incorporated a pulser and additional optics
to direct the beam into the cyclotron.
2. Application: Pulsed Neutron Source
A reconfiguration of the ion source and
injection system allows a pulsed beam to be
accelerated in the cyclotron.
Using a
repetition rate of one pulse every 1 µsec, the
resulting extracted proton beams are used to
Figure 2 Pulsed Deuteron Ion Source and Injection system. The first solenoid focuses a dc deuteron
beam onto defining slits. Pulsed deflector plates gate the beam to the remainder of the injection line and
solenoid and quadrupole lenses.
A buncher is included to increase the beam
intensity and also to compensate for some
space charge effects. For a 0.4 mA dc beam
that is then pulsed to 13.6 ns, the buncher
compresses the pulse to 9.3 ns.
The
compression is less for higher intensity
pulses. Both ion source and injection line
require further configuration to allow
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full energy. For the most intense beam, it
may be reasonable to accept as much beam
as can be delivered from an ion source.
However, using all of the available beam
impacts beam quality. Figures 3 and 4 show
cyclotron beam characteristics as a function
of RF phase of the particle. Both radial and
axial beam distributions show wings that
correspond to the part of the beam that
higher injection line currents and
consequently higher intensity pulsed neutron
fluxes. A similar buncher has been studied
in the TR30 isotope production cyclotron
injection system whose placement differs
from earlier work1 and results in a current
increase of up to a factor of 2.
3. Cyclotron Dynamics
TR cyclotrons have a very broad acceptance
of injected beam that will be accelerated to
10
10
8
8
6
6
4
4
2
2
0
12
40
60
80
100
120
Figure 3 Radial Amplitude (mm) of ion
vs Rf phase of the ion. The full acceptance
of the cyclotron allows large radial
amplitudes.
0
20
40
60
80
100
120
Figure 4 Axial Amplitude (mm) of an
ion vs RF phase of the ion. The full
acceptance of the cyclotron allows large
axial amplitudes
is accelerated far from the central RF phase
peak. The beam spot distributions will
reflect these excursions.
The phase
acceptance of the TR cyclotrons can be
manipulated
by
including
defining
collimators in the cyclotron central region.
Likewise, an external ion source whose
inherent phase space characteristics are
much smaller than the broad acceptance of
the cyclotron avoids populating the large
phase ion trajectories and gives a high
quality axial amplitude beam. This is the
case for the TR cyclotrons whose ion
sources have emittances in the 0.3 mm mR
range as opposed to the full cyclotron
acceptance
of
0.7
mm
mR.
4. Extracted Beam Characteristics
density as presented in figure 6 for the TR19
cyclotron. It is possible to reduce the power
density presented to the target window and
to increase the cooling surface by tilting the
target relative to the beam. However, as the
beam travels through the target material it
still presents a very high current density
profile
there.
The TR cyclotrons extract the ion beams
into external beam lines. In the case of the
basic TRPet cyclotron, the beam line is short
and utilizes the focusing properties of the
outer region of the cyclotron to direct the
beam along the beam line and onto the
target. Figure 5 details these extraction
trajectories. The beam quality is high and
this corresponds to a very high current
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T R P e t B e a m
P r o file
@
ta r g e t
1 6 0
beam current [uA/cm**2]
1 4 0
1 2 0
1 0 0
8 0
6 0
4 0
2 0
0
0
0 .2
0 .4
0 .6
R a d ia l p o s itio n
Figure 5 Extracted Beam trajectories. The
target holder rotates on a bellows to align the
target with the beam.
0 .8
1
(c m )
Figure 6 Beam current density at the target
for TRPet. This is power that is delivered to
the target material by the beam.
5. Target Gas Recovery
Production targets that utilize isotopically
rare gases are very expensive to operate
without a target gas recovery system. An
example of such a process is the proton
induced production of 15O from 15N. We
have been developing a 15N2 recovery
system so that large quantities of 15O can be
produced at a low cost. Figure 7 shows the
operation of the recovery system.
Concentration as a function of time
(100 psi-40cc/min)
Target
He
O2 to synthesis
N2
reservoir
Concentration
Column
0.05
10
9
8
7
6
5
4
3
2
1
0
0
-0.05
-0.1
0
0.001
0.002
Time(days)
0.003
Figure 7 Nitrogen Recovery system.
A bolus of target gas is swept through a column and the output is
switched between an Oxygen routing and Nitrogen recovery line. There is clear separation in time; the dashed
line is Oxygen and the solid line is Nitrogen.
Conclusion
The TR cyclotron systems start at the ion
source and continue to radiochemical
synthesis units. There is ongoing research
and development in all these technologies.
We acknowledge the kind efforts of Univ
Sherbrooke and Cyclotope for making their
facilities available to us for development.
Reference RA Baartman Proc. 14th Accel
Conf.
(1995)
440
998