The TRASCO Project
Carlo Pagani*
University ofMilano and INFN Milano LASA
Via Fratelli Cervi, 2001,1-20090 Segrate (Milano), Italy
Abstract. TRASCO is a joint INFN/ENEA program, started in 1998, aiming at the design and the technological
investigation of the main components of an accelerator driven system (ADS) for nuclear waste transmutation. The
proposed 30 mA, 1 GeV, proton linac (TRASCO-AC) is briefly outlined, together with the ongoing R&D work on
several key components.
INTRODUCTION
The disposal of radioactive waste represents a
problem that is not yet fully solved, especially in terms
of environmental and social acceptability. By using
partitioning and transmutation technologies the most
hazardous materials could be separated (partitioning)
from the nuclear wastes and, then, converted to
shorter-lived elements (transmutation). Transuranic
elements would be transmuted by fission and Fission
Products by neutron capture and beta decay.
Accelerator Driven Systems (ADS) are generally
believed to be particularly suited for assessing the
transmutation of nuclear waste and have become a
major R&D topic in Europe [1].
Important ADS activities are also going on or are
being planned outside Europe e.g., in Japan (the
JAERI/KEK Joint Project), in USA (the AAA project)
and in Korea (the KOMAC Project).
TRASCO PROGRAM OUTLINE
On the basis of a growing interest on the ADS
concepts in Italy, the basic R&D program TRASCO
has been funded in 1998 by the Ministry of the
University, Scientific and Technological Research, and
has been followed by an industrial program, in which
major Italian research institutions and industries are
involved [2]. TRASCO aims to study the physics and
to develop the technologies needed to design an ADS
for nuclear waste transmutation.
The TRASCO program consists of two main parts,
regarding, respectively, the accelerator and the subcritical system. The first part falls under the
competencies of INFN and the second under those of
ENEA, which are the two institutions jointly
responsible of the TRASCO activities, which include
also Italian industrial partners.
The program covers all the main subsystems of an
ADS (accelerator, window/target, sub-critical reactor).
However, due to the limited available financial
resources, all the efforts are concentrated on starting a
few significant and qualified experimental activities, in
view of the goal of a future participation in an
International project dedicated to the study and
construction of an ADS prototype, like, for example,
the PDS-XADS program of the 5th framework
programme of the European Commission.
Reference Accelerator Parameters
The TRASCO accelerator program [2] is focussed
on the conceptual design and the realization of
prototypical components for a 30 MW (1 GeV, 30
mA) CW proton linear accelerator, which is the
candidate for an industrial size transmuter with a
thermal power in the range of 1500 MW.
The coupling of the accelerator with the subcritical
system leads to rather tight requirements on the
accelerator reliability and availability. This reliability
issue therefore is at the base of the linac design,
leading to conservative choices on all components
with respect to the "state of the art" technologies, and
to an appropriate amount of redundancy in the system,
in order to increase the tolerance to component faults
and to achieve beam delivery to the target in the
presence of faulty components, in the time between
regularly scheduled maintenance periods.
General layout
The linac consists in a microwave discharge proton
source, operating at 80 kV, capable of providing 35
mA of CW proton beam, followed by a 352.2 MHz
RFQ up to 5 MeV. A 352.2 MHz superconducting
linac with independently phased resonators brings the
energy to approximately 100 MeV, and the beam is
finally brought to the nominal energy of 1 GeV by a
* On behalf of the TRASCO Linac Group
CP642, High Intensity and High Brightness Hadron Beams: 20th ICFA Advanced Beam Dynamics Workshop on
High Intensity and High Brightness Hadron Beams, edited by W. Chou, Y. Mori, D. Neuffer, and J.-F. Ostiguy
© 2002 American Institute of Physics 0-7354-0097-0/02/$ 19.00
99
three section
section superconducting
superconducting linac
linacthat
thatuses
usesmulticell
multicell
three
elliptical
cavities
at
704.4
MHz.
elliptical cavities at 704.4 MHz.
The main
main objectives
objectives of
of the
the TRASCO
TRASCOprogram
programare:
are:
The
•• The
Theconceptual
conceptualdesign
designofofthe
thewhole
wholelinac;
linac;
The design
design and
and construction
construction ofof the
the proton
proton
•• The
source and
and of
of the
the RFQ
RFQpre-accelerator;
pre-accelerator;
source
The design,
design, construction
construction and
andtest
testofofprototypes
prototypes
•• The
of the
the superconducting
superconducting cavities,
cavities, mainly
mainlyfor
forthe
the
of
high-energy linac.
linac.
high-energy
A schematic
schematic layout
layout of
of the
the TRASCO
TRASCO linac
linac isis
presented in
in Figure
Figure 1.1.
352MHz
352
MHz
SOkeV
100 MeV
MeV
80
keV 55MeV
MeV
100
CW
CW RFQ
RRJ
Low
Lowenergy
energy
Microwave
Microwave
superconducting
superconducting
Proton Source
Source linac
linac(ISCL)
(ISCL)
model has
has been
been built
built and
andhas
hasdemonstrated
demonstratedthethe
model
capability
of
field
stabilization.
Tests
fabrication
capability of field stabilization. Tests ofof
thethefabrication
technology
have
been
performed
on
a
short
model
and
technology have been performed on a short model
and
thefull
fullRFQ
RFQstructure
structureisisnow
nowunder
underfabrication.
fabrication.
the
TABLE1.1.TRASCO
TRASCORFQ
RFQ
Parameters.
TABLE
Parameters.
mA
BeamCurrent
Current
Beam
3030
mA
Beam
Emittance
mmmrad
0.2
n
Beam Emittance
mm mrad
0.2 π
OutputEnergy
Energy
MeV
Output
55
MeV
TotalLength
Length
7.13
Total
7.13
mm
RFInput
InputPower
Power
850
kW
RF
850
kW
MV/m
PeakElectric
ElectricField
Field
Peak
3333
MV/m
704MHz
704
MHz
GeV
1 1GeV
High
Highenergy
energy
su
superconducting
pe rcon ductinglinac
linac
(3(3sections)
sections)with
with
elliptical
ellipticalcavities
catties
FIGURE
FIGURE 1.
1. The
The schematic
schematiclayout
layoutofofthe
theTRASCO
TRASCOlinac.
linac.
In the following sections
sections the
the status
status of
of the
the design
design ofof
the components
components of
of the
the TRASCO
TRASCOlinac
linacwill
willbe
beoutlined,
outlined,
together with
with the
the R&D
R&D ongoing
ongoingactivities.
activities.
TRIPS:
TRIPS: TRASCO
TRASCO Intense
Intense Proton
ProtonSource
Source
High
High intensity
intensity proton
proton sources
sources of
ofseveral
severaltens
tensofofmA
mA
already
already exist
exist but
but additional
additional R&D
R&D efforts
efforts are
are still
still
necessary
necessary for
for ensuring
ensuring the
the availability
availability and
and reliability
reliability
required
by
the
ADS
system.
TRIPS
design
required by the ADS system. TRIPS designisisbased
basedon
on
the
principle
of
microwave
discharge,
off-resonance,
the principle of microwave discharge, off-resonance,
and
and itit is
is aa modified
modified version
version of
of the
the source
source SILHI
SILtfl
operating
at
CEA/Saclay
since
several
years.
operating at CEA/Saclay since several years.
With
With respect
respect to
to that
that source
source some
some things
things have
havebeen
been
changed
and
some
new
features
have
been
changed and some new features have been added.
added.
Mainly
Mainly the
the efforts
efforts have
have been
been concentrated
concentrated on
on the
the
design
of
a
new
extraction
system
with
the
aim
design of a new extraction system with the aim toto
increase the source availability and reliability, in order
increase the source availability and reliability, in order
to meet the requirement of a driver for an ADS system.
to meet the requirement of a driver for an ADS system.
RFQ
RFQ and
and low
low energy
energylinac
linac
Forthe
thelow
lowenergy
energylinac
linacseveral
severaloptions
optionshave
havebeen
been
For
investigated:a anormal
normalconducting
conductingDTL,
DTL,and
anda afew
few
investigated:
superconductinglinac
linacoptions
optionsbased
basedonondifferent
differenttypes
types
superconducting
independently phased
phased resonators
resonators (single
(single gap
gap
ofof independently
reentrant
reentrant cavities,
cavities, half
half wave
waveresonators
resonatorsand
andmore
more
recently
spokes).
recentlyspoke
spokecavities,
cavities,with
withone
oneorortwo
two
spokes).
The
The choice
choice ofof a a superconducting
superconducting linac
linac with
with
independently
independently phased
phased cavities
cavities seems
seems thethe most
most
attractive
attractiveboth
bothininterms
termsofofpower
powerconsumption
consumptionand
andin in
terms
termsofofreliability.
reliability.Spoke
Spokecavities
cavitiescan
canallow
allowa large
a large
beam
beamaperture
apertureand
andcan
canbebedivided
dividedininfew
fewfamilies,
families,asas
done
part
donefor
forthe
theelliptical
ellipticalcavities
cavitiesininthe
thehigh
highenergy
energy
part
The
Thehigh
highenergy
energylinac
linac
From
of of
Fromenergy
energyofofabout
about100
100MeV
MeVthethetechnology
technology
elliptical
superconducting
cavities
represents
the
most
elliptical superconducting cavities represents the most
efficient
efficientand
andcost
costeffective
effectiveone
onetotoaccelerate
acceleratethethebeam
beam
totohigher
higherenergies.
energies.The
TheRF
RFfrequency
frequencyhas
hasbeen
beensetsetto to
704.4
704.4MHz
MHz(twice
(twicethat
thatofofthe
theRFQ
RFQand
andlow
lowenergy
energy
linac)
to
use
the
bulk
Nb
technology
for
linac) to use the bulk Nb technology forcavity
cavity
fabrication,
fabrication, which
whichcan
cannow
nowguarantees
guaranteesoutstanding
outstanding
performances,
performances,thank
thanktotothe
thework
workdone
doneininthethepast
pastyears
years
ininthe
framework
of
the
TESLA/TTF
Collaboration.
InIn
the framework of the TESLA/TTF Collaboration.
order
to
cover
the
desired
energy
range
(from
order to cover the desired energy range (from
~100
areare
-100MeV
MeVtoto1 1GeV),
GeV),three
threedifferent
differentlinac
linacsections
sections
required
and
sufficient,
with
the
cavity
betas
required and sufficient, with the cavity betassetset
respectively
respectivelytotothe
thevalues
valuesof:of:0.47,
0.47,0.65
0.65and
and0.85.
0.85.
These beta choices, while efficient, leave a large
These beta choices, while efficient, leave a large
margin for energy ugrade (ut to 2 GeV). Table 2
margin for energy ugrade (ut to 2 GeV). Table 2
summarizes the main parameters of the three sections.
summarizes the main parameters of the three sections.
The TRASCO RFQ has been designed with the
The TRASCO RFQ has been designed with the
constraints of low beam losses (less than 4%), the use
constraints of low beam losses (less than 4%), the use
of a single LEP type klystron (1.3 MW nominal
of a single LEP type klystron (1.3 MW nominal
power) and a Kilpatrick factor of 1.8 (corresponding to
power)
and asurface
Kilpatrick
factor
of 1.8
(corresponding
a 33 MV/m
electric
field).
Table
1 summarizesto
athe33main
MV/m
surface
electric
field).
Table
parameters of the TRASCO RFQ.1 summarizes
theThe
main
the TRASCO
RFQ. coupled
RFparameters
structure isofsplit
in three resonantly
The
RF
structure
is
split
in
three
resonantly
coupled
segments (similar to the LEDA design). The vane
tips
segments
(similar
to
the
LEDA
design).
The
vane
tips
have a fixed transverse radius of 2.93 mm, and the
have
a
fixed
transverse
radius
of
2.93
mm,
and
vane voltage is kept constant along the structure, the
to
vane voltage
kept constant
along3 the
reduce
power isdissipation.
A cold
m structure,
aluminiumto
TABLE 2. TRASCO 704.4 MHz SC Linac Params.
TABLE 2. TRASCO 704.4 MHz SC Linac Params.
Section #
1
2
3
Section #
1 0.652
3
0.47
0.85
Section Geometrical βg
0.47
0.65
0.85
Section
Geometrical
p
Input Energy [MeV] g
90
190
480
Input Energy
90 480
190 1000
480
Output
Energy [MeV]
[MeV]
190
Output
Energy
[MeV]
190
480
1000
Lattice Period [m]
4.2
5.8
8.5
#Lattice
Lattice Period
Periods[m]
144.2
165.8
128.5
14
#
Lattice
Periods
16
# Cells/Cavity
5
5
6 12
#
Cells/Cavity
5
5
Cavity Eacc [MV/m]
8.5
10.3
12.36
Cavity
Eacc
[MV/m]
8.5
10.3
# Cavities/Cryomodule
2
3
412.3
# Cavities/Cryomodule
reduce power dissipation. A cold 3 m aluminium
100
2
3
4
A set of multicell cavities for all three linac sections
set of multicell cavities for all three linac sections
hasA been
designed, taking into account both the
has been designed, taking into account both the
optimization of electromagnetic performances (in
optimization of electromagnetic performances (in
terms of peak fields on the surface) and mechanical
terms of peak fields on the surface) and mechanical
performances (stability under vacuum load, stiffness
performances (stability under vacuum load, stiffness
for microphonics and Lorentz forces excitation).
for microphonics and Lorentz forces excitation).
Conservative
values with respect to the state of the art
Conservative values with respect to the state of the art
technology
of
used in
in
technology of the
the TTF
TTF cavities
cavities have
have been
been used
terms
of
maximum
peak
design
electrical
and
terms of maximum peak design electrical and
magnetic
30 MV/m
MV/m and
and
magnetic fields
fields on
on the
the surface
surface (set
(set to
to <
< 30
<< 50
mT),
in
order
to
increase
the
reliability
of
the
50 mT), in order to increase the reliability of the
proposed
technology.
proposed technology.
A total of four p=0.47 single cell cavities have been
A total of four β=0.47 single cell cavities have been
built
with the TRASCO industrial partners, two of
built with the TRASCO industrial partners, two of
which using low grade niobium sheets (RRR>30) and
which using low grade niobium sheets (RRR>30) and
two using high purity sheets (RRR>250). The vertical
two using high purity sheets (RRR>250). The vertical
tests were very successful in all four cases. Both the
tests were very successful in all four cases. Both the
cavities produced with low quality, and cheap,
cavities produced with low quality, and cheap,
niobium
exceeded the design parameters, showing a
niobium exceeded the design parameters, showing a
hard
quench
an accelerating
accelerating field
field value
valueofof10-11
10-11
hard quench atat an
MV/m.
The
best
of
the
other
two
cavities
(Z104)
MV/m. The best of the other two cavities (Z104)
reached the
the record
record accelerating
acceleratingfield
fieldofof22
22MV/m,
MV/m,the
the
reached
10
10 up to > 20 MV/m. The other
Q
staying
above
10
Q staying above 10 up to > 20 MV/m. The other
(Z103) was
was limited
limitedto
to20
20MV/m
MV/mby
byfield
fieldemission.
emission.
(Z103)
In
Figire
2
the
test
results
on
the
two
bestcavities
cavities
In Figire 2 the test results on the two best
are presented,
presented, showing
showing also
alsothe
thecorresponding
correspondingvalues
values
are
of
the
peak
electric
and
magnetic
fields.
Treatments
of the peak electric and magnetic fields. Treatments
and tests
tests were
wereperformed
performedatatTJNAF
TJNAFand
andCEA-Saclay.
CEA-Saclay.
and
Beam
simulations
Beam dynamics
dynamics analysis
analysis and
and simulations
The
high
The whole
whole linac
linac has
has been
been designed
designed using
using high
current
at minimizing
current beam
beam dynamics
dynamics criteria
criteria aimed
aimed at
minimizing
the
and particle
particle
theoccurrence
occurrence of
of beam
beam emittance
emittance growth
growth and
losses.
and
losses. In
In particular
particular structure
structure and
and tune
tune resonances,
resonances, and
strong
tune
depression,
have
been
avoided
in
the
strong tune depression, have been avoided in the
design
and
a
smooth
variation
of
all
linac
parameters
design and a smooth variation of all linac parameters
has
has been
been guaranteed.
guaranteed. Proper
Proper adiabatic
adiabatic matching
matching
procedures,
at the
the
procedures, have
have been
been developed
developed and
and employed
employed at
section
section interfaces
interfaces [4].
[4]. The
The validity
validity of the design has
been
been assessed
assessed by
by means
means of
of multiparticle simulations
with
withstandard
standardbeam
beam dynamics
dynamics codes.
11
10
10
11
Z103
Z104
Q0
1U
10
10
10
-design
designvalue,
value,BEM-50
mT;
=50 mT
p
"
EE=30.3
=30.3
MV/m,
E
=8.5
MV/m
p
acc
R&D
R&D ON
ON LINAC
LINAC COMPONENTS
COMPONENTS
io9y
10
In
In addition
addition to
to delivering
delivering a conceptual design report
for
foran
anADS
ADS driver,
driver, the
the TRASCO
TRASCO program
program foresees the
realization of
of prototypical
prototypical activities on critical
realization
critical
components of
of each
each section
section of the proposed linac. The
components
most representative
representative examples
examples of these activities are
most
are
described in
in the
the following
following paragraphs. More
described
information on
on the
the status
status of
of the
the different
different components
information
can
be
found
in
[4]
and
in
the
references
can be found in [4] and in the references there quoted.
Noquench
quench
No
0
20
20
0
10
10
00
22
44
40
40
20
20
66
60
60
30
30
8080
40
40
100
100
5050
1 Quench
Quench
120
120
6060
140
140
7070
i
.
88 1010 1212 1414 1616 1818 2020 2222
BBp p[mT],
[mT],EEp p[MV/m],
[MV/m],EEaccacc[MV/m]
[MV/m]
FIGURE
FIGURE2:
2:RF
RFtests
testsofofthe
theZ103
Z103and
andZ104
Z104cavities,
cavities,made
made
with
with high
high quality
qualityniobium
niobium(RRR
(RRR>>250).
250).
On
On the
the basis
basis of
of this
this experience
experiencethe
the construction
constructionofof
two
two complete
complete five
five cell
cell cavities
cavitieshas
has been
beenlaunched.
launched.AA
more
complete
description
is
given
in
ref
[4].
more complete description is given in ref [4].
TRIPS operation
TRIPS
The TRIPS
TRIPS source
source has
has been
been assembled
assembled in
in LNSLNSThe
Catania
in
May
2000,
commissioned
in
January
Catania in May 2000, commissioned in January 2001
2001
with aa 20
20mA
mA beam
beam at
at 60
60 kV
kV and
and finally
finally achieved
achieved 55
with
55
mA of
of beam
beam current
current with
with 90%
90% of
of proton
proton fraction
mA
fraction
duringbeam
beamtests
tests in
in August
August 2001
2001 [4].
during
[4].
REFERENCES
REFERENCES
[1]
[1] EU
EU Tech.
Tech. Working
Working Group
Group on
on ADS,
ADS, “A
"A European
European
Roadmap
Roadmap for
for Developing
Developing Accelerator
Accelerator Driven
DrivenSystems
Systems
(ADS)
(ADS) for
for Nuclear
Nuclear Waste
Waste Incineration”,
Incineration", April
April 2002,
2002,
http://www.neutron.kth.se/TWG22/default/index.html.
http://www.neutron.kth.se/TWG22/default/index.html.
[2]
[2]TRASCO
TRASCOPartners
Partnersfor
forthe
theaccelerator
acceleratorprogram
programare:
are:INFN
INFN
and
the
Italian
companies
HITEC,
CINEL,
Saes
and the Italian companies HITEC, CINEL, SaesGetters,
Getters,
CESI
CESIand
and ZANON.
ZANON.
Fabrication of
of the
the TRASCO
TRASCO RFQ
Fabrication
RFQ
The RFQ
RFQ design
design has
has been
been engineered,
engineered, in
The
in
collaboration
with
the
industrial
partners
collaboration with the industrial partners and
and the
the full
full
structure isis now
now in
in the
the fabrication
fabrication stage
stage [4].
[4]. Special
Special
structure
attention during
during the
the design
design has
has been
been dedicated
dedicated to
to the
the
attention
optimisation
of
the
cooling
channels.
optimisation of the cooling channels.
[ ]
[3 ]
3 The
The TRASCO_AC
TRASCO_AC Group,
Group,“Status
"Statusofofthe
theHigh
HighCurrent
Current
Proton
Accelerator
for
the
TRASCO
Program”,
Proton Accelerator for the TRASCO Program",INFN
INFN
Report INFN/TC-00/23, December 2000, available from
Report INFN/TC-00/23, December 2000, available from
http://wwwsis.lnf.infn.it/pub/INFN-TC-00-23.pdf.
http://wwwsis.lnf.infn.it/pub/INFN-TC-QO-23.pdf.
[4] Papers
THBLA002,
TUPLE121,
WEPLE109,
[4] Papers
THBLA002,
TUPLE121,
WEPLE109,
THPDO022, THPDO023, THPLE083 are being
THPDO022, THPDO023, THPLE083 are being
presented at EPAC2002 and will be in its Proceedings.
presented at EPAC2002 and will be in its Proceedings.
SC cavities
cavities for
for the
the high
high energy
energy linac
SC
linac
single gap SC re-entrant cavity (at the 352.2 Mhz
AA single
gap SC re-entrant cavity (at the 352.2 Mhz
frequency) has been designed and manufactured. A
frequency) has been designed and manufactured. A
report of the performances obtained is found in ref [4].
report of the performances obtained is found in ref [4].
101