Post Off Ice Box 1663 Los Alamos, New Mexico 87545 ... A New Low-Energy ..... New York:Rhll. Potter. J M, Wil?iams. S W, Humphry F J, and Rodenz C W 107q ...
TITLE :
THERF QUAJJR~OLE
LINAC
:
A NEW LOW-.NERGY ACCELERATOR
L.
D.
Hansborough,
J.
E.
Stovall,
AUTHOR(S): R.
W. Harem, K.
R. Crandall,
C.
W. Rodenz,
R.
C.
W. Fuller,
M. D, Machal.ek,
H. Stokes,
R. A.
J.
M. Potter,
D. A. Swenson,
Jameson,
K. A. Knapp,
T. and
P. S.
Wangler, W. Williams
SUBMITTED TO:
lnternatiorml University
Conference of
Bath
on Low Energy
- 14th-17th
April.,
Ion
Beams
2,
1980
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0
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LOS ALAMOS SCIENTIFIC LABORATORY Post Off Ice Box 1663 Los Alamos, New Mexico 87545 An Affhnative Action/Equal OpportunityEmployer
UN ITCIJ I) RPANTMMNT --..-—. —..
ET ATKs oF’
Kl:KtQov
The W Quadruple
Linac:
A New Low-Energy
Accelerator*
.
R. W. Ham,
K. R. Crandall,
R. A. Jameson,
E.
A.
Knapp,
G. W. Rodenz, D. A. Swenson,
Los
*work
Alamos
performed
National
National
under
Cancer
Los
Alamos
T.
the
auspices
14. D. Machalek,
Stokes,
R.
H.
P.
Wangler,
Scientific
J. and
Laboratory,
of
L.
the
U. S.
E.
S.
Los
D. Flansborough J.
M. Potter,
Stovall, W. Williama~
Alamos,
Department
NM 87545
of
Energy
USA
aud
the
Institute.
~West~nghouse/Hanford the
C. W. Fuller,
National
Engineering
Development
Scientific
Labort?tory.
Laboratory
employee
working
at
-2-
A new concept quadruple
in (RFQ)
National
Scientific
both
focusing
It
the can
accept
particle
is
linac,
Laboratory. and
The
accelerator
haa
proton
RFQ linac.
‘1’his test
than
80%,
lifie
of
the
In
this
th(~ basic
experimi’ntal
applications
In
keV in
this
are
performance
verified
1.1
the
new accelerator
the
has
meters
design
of
with
structure
from
dc
with
produced ion
accelerated
are
accelerator. are
diacusfied.
Alamos structure
as
fields. it
with
78 mA of
RFQ linac
presented Finsllv,
in
a
a lo~~energv
construction
efficiency the
rf
hunch
structure
successful
of
Los
bv the
beam and
this
description
t~st
the
accelerating
a capture
procedure
radio-frequency at
new linear
forces
a general
RFQ linac results
of
been
paper
this
the
developed
low-velocity
linear
100 keV to 640
being
accelerating
efficiency.
from
accelerator,
currently
a high-current,
capture
high
low-energy
of
r,
protrins
greater and addition several
an olltto
-3-
Introduction
1.
Conventional drift-tube
linac,
bunching Large
for
electrostatic
input
heen
energy
opveral
he uoed
❑agnetic
radial
previous
lower
WIIII initiated
Alamoa
National conc~pt,
1970)
A nerien
in
which
a prototype
Recent
has
generated
of
this
was ba~cd
the
codes
rf
the
idea
cold
have
r~dio-fraquencv
led
reducing
there
have
lq63; fields
need
for
could
external
becaune
rf
wan proponed
on a four-conductor quadruple
gaps
or
develop mod~ln co the
focua{nR
waveguideq
forces,
Technolo~:y to
1956
requirement,
fneueing
(L4S1.)
for
elect~ic
●lectric
Acrelerntor
interest
velocity.
ohfiped
localizcvl
and
and Teplyakov,
eliminate
of
oource,
ideas Since
●nergy
specially
evoilitionary
simulation
required.
uniform
Laboratory of
are
accelerating
injector
form
used
1978
hunchers,
independent
LO produce in
of
would
{I npatially
propoaala
Scientific
te~ting
~ig
forcer
produced
beam dynnmico
the
ion
cavity
Anisimov
that
the
rf
c and a rf
from an
●fficiency.
capture
prorising
accelerator
●ffort
Iinac@
1?56;
1963)
and Teplyakov, that
the
focusing
n particularly
conventional
successful
al..
an electric
The
computer
et
in
configuration
wifh
v > 0.04
dc beama
systems
focused
magnetically
velocity
complex
(Vladimirakii,
●nd also
(Kapchinnkii
this
increasing
focuoing
Tn 1~70
beams
ion
the
of
kV),
beam transport
Fer
for
self-focusin~
field,
(>500
and
1964;
particle
injectors
euggestiong
Teplyakov, al~o
an input
acceleration
intense
as
ouch
●fficient
low-energy
acceleratin~
the
accelerator,
req-lire
system
complicated in
linear
Div{nicm
of
th~
model
Lhe nanistance
construction
quadruple
a
An intensive
● wrkin~
and
in
(RFQ)
LoH
of of
and accelerator,
-4-
2,
Description In
the
●rranged
of
RFQ the
tips
equal
have
quadruple half
●trength
independent
in
one
●re
through
one
modulation where
field
at
plnne
of
io generated
two orthogonal Adjacent
evary
other
The
unit cell
shape fieldn
solution
for to
defocusing
tip
contains frnm
of
radii
are
radius
when
the
lenRth
the
have
the
a transverse
the
other
Iowat
hv an (Stok@a
beam with
the
vane
Fig.
!.
tips
the
excitation. the
correapondfi
tip
vane
a cut
at
the
racliusi (3A;?,
longitudinal
The
one
the
structure,
minima
in
tlw
acceleration
fieldH
The
●lectric
field
no that
onlv
distribution
●nd hnn bem
functitwt
and Teplvakrw,
ln70).
tips
neceanarv
●qu{potential
eurface
minimum
the
a
orthogonal
2 shown
axial
potentinl
●l,,
the
vane to
with
with
directed
bunch,
@t
in
the
longitudinal
param~ter
of
van~
giving
a
in
cell
between
half, syotem
Figure
radius
rf
●ach plane
varied,
● unit
oppositely
waler
focusing
a constant
in
focusing
of
cell
a partifilc
deecribecl
onlv
periodically
the
length
unit
hyperhola-likr
structure
●ccelerate
cell
the
in
and defines
(Knpchinnk;i
the is
th~
th~~
then
during
velocitv.
an shown
thir
celln
described
electric
eeaary
and
are
is
at
1.
vane
tips
z-axin, field
●djacent
vane
To generate
vanen,
within
planes,
can be obtained previously
the
●nd A in the wavelength
v/c
flap.
If
particle
radiun,
m,
sign.
electric
vanes in Fig.
time,
ent
vane
the
any given
the
by four
schematically
an alternating-~radi
a minimum
a maximum
parameter
~ :
the
the
plarw
●t
of of
fields
and
seen
at
denigrated This
as
generated
bo that
oppooite
period
is
beam axi.a,
pwer
present. rf
distribution
the
rf of
properties
accelerating
plane
ie the
of
the
with
be~m axis,
field
structure
tips
●round
voltages
the
along
field
electric
●xcited
are
during
RFQ
e~etrically
The vanea
radius
the
to
pro.lute the
in
1~70).
The
correct
loco,
●nd thin
is
the
corrwt
electro~tatit
nhap~
in
accompliahwi
ntwIw
-5-
fabricating
these
(Fuller,
Williams
Several the
and
four-vane
aymnetrical, the
coupling
circuit
used
vane
tip
could
and
tapered
to
a very
short
matchorl
into and
accelerated. thv
beam
mill
that
et
cavity
fields
necessarv
1979).
bem
previously
a
spe:.1.~1
manifolc!
having
model
the
rf
addition,
the
al.,
and
and
In
lo-power
Rl\~ as
circuit
detemnined
surface
(Williams
tunera
A coupled
197qJ.
cavity the
end
of the
by a coaxial
resonant
(potter,
develop
drive
to
a serieq
to
with
cavity.
four-vane
four-vane
After
cavities
that
power
a pow~r
sparking
limit
far
:
test
of
the on
accelerat
Precedurc
the
accelerating
driven
this
developed
showed
approach
at
LASL
1979).
In
the
and Wangler,
sections:
vertical
resonant
been
mode
1979),
the
obtained
RFQ Design
shaper
been
has
a TE210-like
to
for
1968).
IJWL effort
al.,
of
an unmodulated
The RFQ dcsiRn
.
et
suggested
Stepanov,
coupling
has
be reiiably
Stokes
and
in
properties
fields
been
the
(Potter
multislot
de~cribes
that
have
operating
tenninatioas
controlled
1979).
❑odels,
cavity
a numerically
Potter,
RFQ (Teplyakov
on various
vane
with
configurations
four-vane
studies
3.
surfaces
radinl
matching
section.
In
adjust
th~
distance the the
At reachen
most
section,
the
strength
to allow
the
focusing.
huncher,
end
itn
final
of
the
the
gentle
value
und
almost
injected Tn the
beam
is
to
into
the
hunched
combines
and
full
i~ then
the
is value
structure
two sections,
synchronous
four
aperture
ita
bun
beam
fCrandall,
buncher,
vane
zero
next
the
it
gentle the
ndiabqticallv
buncher, the
the
nectirm
from
dc beam
clencribed
application,
shaper,
matching
focusing
the
gen~rnl
the
radial
time-dependent gentle
11:s
in
to he th~
!\ed am it
phaae accelerated
in
angle
of in
-6-
the
final
phase
section.
angle
eration
are
the
frequency
inn and
the
vane These
z-axis. focusin~,
will
functions
are
constant
and
voltage
parameters
and
independent
the
vane
values
work,
radius,
vane
modulation
to
obtain
the
maximum
and
final
energy
tire
bl’t
and
possible
arrangement.
of
accel-
640
enerRy, of
the
have
shown
calculations.
input
the capture
i!iput that
energy the
This
used
test
and
the
the
the radial
specified for
for
these complex
emittance
growth.
accelerator
RF(J cavity
and
42SKHZ
rf
RFQ was optimized The RFQ design
available.
along
accelerator.
an exieting
The
for
was
Figure
? is
power
manifold
source, the
yielded
a
rf
fre-
a f:.nal
structure. of
efficiency,
RFQ performs
test’
given
more
RFQ as a low-energy
showinR
110,8-cm
feasibility
leases
determined
forms
increases
the
is
criteris
simple
force
power
injector.
beam c[lrrent the
full
accelerator
Froton
keV for
A
the
are
and
to produce
other
cu?~ents,
p~rticle
accelerator,
test
and
To establish
tion
this
100-keV
quency,length, energy
of
of
and
space-charqe
evaluating
construction
This
and
in
angle
determined
length,
low beam
the
he
given,
RFO design
phase
must
growth,
as
the
synchronous
to minimize
step
view
specified,
functions
necessary
and
are
For
An essential design
initial
the
emittance
Results
cavity,
the
intervane
Experimental
schematic
final
section,
application.
functions
the
at
~pecies
capture,
a particular
4.
held
this
gradient.
If
when
In
the
and and
RFQ as
emittance
the
near
a low-energv
rf
field
the
levels
RFQ ham operated
rel.iahlv
growth
were
h~!ldied
These
level. predicted at
acr.eleratnr,
rf
as
n func-
mcneurerncnt:,
by the fields
tho
beam
ciynnmir~
35% Rroater
-7-
than
the
desiign
beam
injected
magnetic be as
small
as
tip
and
rms
Fig.
5.
proton
in
field
of
of
All
by
apply
to
640
80% of
keV,
as
beam
the
a 38-mA proton
verified energy
to
of
-.
with
a 45°
spread
can
the
as
(100-keV)
reauita
beam
cw operation
the
of
in
from are
the
However,
power.
of
for
due
to
in
and
limitations
injector
the
a
100 keV
experimental
cliugnostics with
the
pulsed
and
shown
the
the
etruc-
transmission are
from
for
the
44 kV,
calculated
primarilv
of
into
beam currents
beam
limits
injected
and
input
being
transmission
voltage
The difference
experimental
rf
intervane
injected
~crtmnrad.
and
a 37-mA beam an
different
dissipation
and measured
The measured
MV/m.
be explained
tlleae
injector
results
of
than
calculated
RFQ with
low-energy
the power
available
the
rms emittance
can the
the
for
was 0.007
of
of
29.6
growth
results
required
energy
corresponds
field
injector
these
results
The normalized
structure.
5s
the
emittance
transport
more
With a 15-mA injected
atrengtha
surface
calculated
accelerated
a final
system.
The design
vane
has
3% FWHM.
field
ture.
and
100 keV to
4 shows
relative
the
at
analyzing
Figure
the
value,
to
in
the
RFQ
operation, equipment
necessary
and
inpui
by
power,
structure,
RFQ Applications In addition
several
RYQ linacn
an 80-MHz portion
to
of
RFQ to
the
proton
now being accelerate
a loo-mill,” 35-MeV,
Fusion
Materials
1979),
(2)
irradiation
a 440-MHZ protou
test
accelerator
studied
from
cw linac Teat
RFQ for
designed
or
deuterons
described at
(FMTT] the
LASL.
100 keV to
to be unecl as facility low-enerRv
above, These
2 MeV aa
a neutron
(Kemp, portion
th~re
are
include. the
initial
generator
Liaka, of
and a Pion
(1)
for
Machal~k, Generator
a
-8-
for
Medica I Irradiation
RFQ as
the
fusion
(Swenson,
Icw-energy
acceleration 1980),
of
(5)
6.
the
1980), all
of
(4)
io
a 200-MHz
low-energy
(Knapp
portion
Swenson,
ion
the
(Harm, of
to
a multichannel
inertial
confinement
research
1 MeV/nucleon
(Stokes
of highly
and
existing
for
(3)
physics
acceleration 1979),
1980)s
driver
a general-purpose
RFQ for
portion
and
a heavy
s up to Peon,
Ream Ion Source
Electron of
(PI@fI)
(6)
proton
and
charged
a 201.25-MHz linac
RFO for
the
Wangler,
ions
from
RFQ for
an
improvement
facilities.
Conclusions Other
applications
utilization
as
increase. dc ion
beam
applications. space-charge
a
of
These.
features allowing
for the
it
RF() are
to
a conventional are large
already both
adiabatically
I accelerate into
have
accelerator
protons),
injection
force,
RFQ linac
advantages
(50-keV (>90%),
for
the
a low-energy
The major
efficiency venient
of
light that
bunch an energy
it
with limits
suggested,
and
it
heavy
will
with
a high
lirlac minimnl with
so ions
accept
(several
drift-tube
accomplished currept
been
mnall
for
should
a low-energv capture
MeV) that or
its
is
con-
other
effects emittance
frorr,
t+e
growt6.
-9-
References
Anisimov
G M and Teplyakov
Crandall
K R, Stokes
Conf. Fer
F,
Linear Fuller
R H, and
(Montauk,
Lapostolle
New York: P,
Beith
Accelerators
(Montauk,
Kemp E L, Conf. Knapp
therapy
D J,
(Montauk,
E A and
J M 1979
Potter
J M, Wil?iams Nucl.
Stokes
Proc.
NS-26
R H, Crandall
Nucl. Stokes
Sci.
New York:
Sci.
Proc.
1979
C 1963
J M 1979
Accelerator
Linear
Proc.
Proc.
NS-26
R H and Wangler
Conf.
V A 1970 Prib.
Accelerator
Int.
Conf.
on
1979 Linear
Accelerator
M D 1979
(Montauk,
Tekh. Proc.
Eksp. 1979
New York:
EtW.).
~ 19.
Linear
Accelerator
BNL).
D A 1979
(Kyoto,
Potter
Cabrespine
Potter
and Machalek
Swenson
Conf.
T P 1979
~ 21.
JINR~.
1979 Linear
I M and Teplyakov Liska
Eksp.
New York:BN1.).
Hanm R k! 1Q79 Proc. Kapchinskii
Tekh.
BNL).
C, and
S W, and
Prib.
Wangler
(Dubna:
C ‘J, Williams Conf.
V A 1963
Proc.
High
LI?T and
Allied
Arean
{n
Radio-
Japan).
1979 Linear S W, Humphry
Accelerator
Conf.
F J,
and
Rodenz
J E,
and
Swenson
(Montauk, C W 107q
New York:Rhll. IEEE Trans.
on
3745. K
. Stovall
D A 1~79
3469. T P 1980,
private
conm!unication.
IEEE Trans.
on
-1o-
Swenson
D A 1980 Proc.
of
Heavy
Ion
Fusion
Accelerator
Study
(Berkeley,
CA:
Physics
13 1724. —
LBL ) . Teplyakov
V A 1964 Prib.
Teplyakov
V A and
Vladimirskii Williams
Stepanov
V V 1956 S W, Rodenz
Accelerator
Tekh.
Conf.
Frib.
Eksp.
V B 1968 Tekh.
Radio
Eksp~
G W, Humphry (Montauk,
~ 24.
F J,
Eng.
and Electronic
35. and Potter
New York:BNL).
J M 1979 Proc.
1979
Linear
-11-
List
Fig.
1
Schematic
Fig.
2
The
Fig.
3.
Schematic
Fig.
4.
Transmission
of
points
the
view
RFQ vane-tip
shows
generated 5.
of
of
predictions
Captions
LASL four-vane
the
the
the
from
RFQ as
beam
structure.
the the
test
accelerator.
a function
of
values dynamics
injected
growth give
425-MHz
meaaured
particles
RMS emittance The poi;ts
the
Figure
geanetry.
view
prediction
Fig.
of
of
and
the
transmission values dynamics
the
excitation.
solid
cal-uation
into
measured beam
and
rf
curve
for
5000
The is
the
randomly
RFQ.
for and
various
the
calculations.
solid
input
curves
currents.
are
the
-12-
Title
THE RY QUADRUPLE LTNAC: A NEW LOW-ENERGY ACCELERATOR
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