Transcript SCDTL study for ERHA design

SCDTL study for ERHA
C. Ronsivalle, L. Picardi
ADAM meeting Geneve, 09-02-2010

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TOP-IMPLART (ENEA-ISS-IFO Project in
Rome) and EHRA Project (Ruvo di Puglia) do
not require radioisotopes production at low
energy and foresee for their protontherapy
complex a completely linear structure.
In the following the design of a SCDTL structure
up to 35 MeV is presented to be used for TOPIMPLART and EHRA Projects; the first part up to
17.5 MeV is equal to the structure under
development in the framework of the ISPAN
Project launched by ENEA-ISS-NRT-CECOM
(funded for about 500 K€)
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ISPAN (“Irraggiamento Sperimentale con
Protoni per modelli cellulari ed Animali”) Project

The Project foresees the realization
of a test facility at ENEA-Frascati
laboratories by using as injector a
PL7 425 MHz linear accelerator
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SCDTL
Outline
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DESIGN CRITERIA OF SCDTL35
SCDTL35 LAYOUT AND PARAMETERS FROM DESIGN
CODE OPTIMIZATION
BEAM DYNAMICS IN SCDTL35:
- LINAC code results
- Matching with the 7 MeV injector (PL7)
- Losses distribution (checked also with TSTEP code)
- Errors and tolerances study in SCDTL35
- Start-to-end up to 235 MeV including LIGHT35 (from DeGiovanni dataDecember 2009 version)
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CONCLUSIONS
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Main design criteria and constraints
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INJECTION ENERGY: 7 MeV
OUTPUT ENERGY: 35 MeV
ONE 10 MW KLYSTRON WITH A POWER CONTINGENCY
OF 3 MW (P<7 MW)
NUMBER OF MODULES: 4
EXTERNAL PMQs WITH A MAXIMUM GRADIENT OF 220
T/m (useful radius for protons =2.9 mm) FROM ASTER
MAIN DIFFERENCES RESPECT TO SCDTL DESIGN FOR
TOP linac (ENEA Technical Report RT/INN/9717,1997)
RELEVANT FOR BEAM DYNAMICS:
-The old design assumed internal PMQ (Leff=30 mm) with an intertank
distance varying in the range 7-35 MeV between 43 and 65 mm too short
for allocating external PMQs  (Transverse acceptance1/max, and
max  Lperiod)
- Higher electric field gradient (limited to12 MV/m in the old design) are
required to reduce the total length: attention to keep /maxconst. In the
allowed range of PMQ gradients and to avoid parametric resonances and
longitudinal instability) (phase longitudinal advance l  EOT)
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SCDTL35 LAYOUT
Modules 1-2
Modules 3-4
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SCDTL35 ELECTRICAL PARAMETERS
* Include flat stems and 20% of coupling losses
Total RF power consumption= 6.57 MW
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RF EFFICIENCY
FLAT stems for an
efficient stem cooling
P=1.4 MW
Cylindric stems
(diameter=5 mm):
no stem cooling
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THEORETICAL BEAM DYNAMICS
PROPERTIES (from DESIGN data, assuming constant
normalized transverse, that means negligible coupling between
transverse and longitudinal planes and perfet matched FODO lattice)
Transverse acceptance (At=r2/TWISSmax)= 8.7  mm-mrad
 Longitudinal
phase stable
area (foreseen phase
acceptance58.5°=3|s|)
 INJECTOR: PL7 OUTPUT BEAM PARAMETERS

Exun Exun Eyun Eyun
(100%) (rms) (100%) (rms)
 *
(deg)
DW *
El
(keV) ( deg-MeV)
-----------------------------------------------------------------------------6.6 (100%) 1.1
4.4 (90%)
7.2(100%) 1.2
59°
4.8(90%)
(at 2998 MHz)
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93.3
5.411
(at 2998MHz)
* Half width
BEAM DYNAMICS: LINAC CODE RESULTS FOR
AN IDEAL MATCHING BETWEEN PL7 AND
SCDTL35 (distance from injector=0)
M1
100
90
80
70
60
50
40
30
20
10
0
M2
M3
M4
Transmission (%)
Energy(MeV)
0
0.5
1
1.5
2
2.5
3
3.5
z(m)
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4
4.5
5
5.5
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Input coordinates

Accepted coordinates in the three phase space planes

SCDTL35 output beam: transmission=46.3%
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BEAM QUALITY IN THESE CONDITIONS: EMITTANCE
3
Exun_rms
Eyun_rms
mm-mrad
2.5
RMS unnormalized
emittance
at 35 MeV:
0.7  mm-mrad
2
1.5
1
0.5
0
0
0.5
1
1.5
2
2.5
3
z(m)
3.5
4
4.5
5
5.5
0.4
Exn_rms
Eyn_rms
0.35
mm-mrad
0.3
RMS normalized
emittance
at 35 MeV:
0.2  mm-mrad
0.25
0.2
0.15
0.1
0.05
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
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z(m)meeting Geneve, 09-02-2010
5.5
Phase half width
(deg at 2998 MHz)
EFFECT OF INJECTOR BUNCH LENGHTENING ON
300
SCDTL
TRANSMISSION
250
Bunch lenghtening
due to velocity spread
in a drift following the
injector
200
150
100
50
0
0
20
40
60
80
100
120
Injector-SCDTL distance (cm)
140
PL7 425 MHz
PL7 428 MHz
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transmission vs
distance between
injector output and
center of the first PMQ
on SCDTL: (matched
beam on transverse
planes)
MATCHING PL7 at 425 MHz – SCDTL35 (3 EMQs in a LEBT 1
m long before the PMQ at the SCDTL entrance) compatible with
the current Frascati installation and ISPAN scheme
Total length (up to the middle of the
PMQ at the entrance of
SCDTL)=1131.74 mm

X-envelope
-
+
Y-envelope
-
+
-----------------295--- ------------><-------150-------<--70-------150-------70---------150---------------231.74------------><15
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MATCHING PL7 AT 428 MHZ-SCDTL (3 PMQs in the a very
short LEBT before the PMQ at the SCDTL entrance) to be
discussed with ACCSYS
Total length (up to the middle of
the PMQ at the entrance of
SCDTL)=293.33 mm

X-envelope
-
+
-
+
<--16 -><----30-----<----------------80--------------------------30-----<----------------80----------------------------30---<12.33><15
Y-envelope
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LINAC code output in these conditions
Accepted

PL7 output coordinates in the three phase space planes
SCDTL35 output: beam transmission=33.7%
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TSTEP code: LOSSES DISTRIBUTION IN SCDTL
TANKS AND AVERAGE ENERGY OF LOST
PARTICLES
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TSTEP code: LOSSES DISTRIBUTION IN TERMS
OF POWER
Lost Power for 1 uA of injected beam (W)
1.2
1
0.8
0.6
0.4
0.2
7
T2
5
T2
3
T2
1
T2
9
T1
7
T1
5
T1
3
T1
1
T1
T9
T7
T5
T3
T1
0
Plot normalization: injected current from PL7=1 A
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ERRORS AND TOLERANCES STUDY
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ERRORS AND TOLERANCES: PMQs
Nruns=50, Random errors
(uniformly distributed in  |error|)
Effect on transmission:
markers position on the points
corresponding to a factor=0.9 on
transmission for a loss with probability
of 90% - Rot. angle=2°,
gradient=4%, displacement=50m
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ERRORS AND TOLERANCES: TANKS
Nruns=50, Random errors
(uniformly distributed in  |error|)
Effect on transmission:
markers position on the points
corresponding to a factor=0.9 on
transmission for a loss with probability
of 90% - Field amp. error=2%, tank
displacement=150 m
entire tank is displaced
independently in x,y
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each end of tank is
independently displaced (tilt)
ERRORS AND TOLERANCES: PHASE SHIFTS
Nruns=50, Random errors (uniformly distributed in  |error|)
Effect on transmission:
markers position on the points corresponding to a factor=0.9 on transmission
for a loss with probability of 90% error in distance between tanks=150 m,
error in the length of the cells=50 m
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ERRORS AND TOLERANCES (Total Np=100K, nruns=300)
PMQs: Rot. angle=2°, gradient=4%, x-y displacement=50m
TANKS AND CELLS ERRORS: Field amp. error=2%,
tank displacement=150 m
error in distance between tanks=150m,
error in the length of the cells=50 m
Prob=90% of
transmission/max.
transmission>50%
Prob=90% of
Exn<0.28 mm-mrad,
Eyn<0.29  mm-mrad
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THE LOW ENERGY SCDTL PART 7-17.5 MEV IS MORE CRITICAL
RESPECT TO TOLERANCES (that can be relaxed in the last two modules)
7-35 MeV
17.5-35 MeV
tolerance on
tank field
amplitude
error from
2% to 6%
7-35 MeV
17.5-35 MeV
tolerance on
PMQ
displacement
from 50 m
to 100 m
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START-TO-END
(7-235 MeV)
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START-TO-END: SCDTL35+LIGHT35(retrieved
from DeGiovanni DESIGN data-December 2009)
SCDTL35
beam portion that is transmitted up to 235 MeV in LIGHT35
The total capture drops from
33.7 % at SCDTL output to
20 % at LIGHT35 output.
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START-TO-END: possible revision of LIGHT35 to
optimize the matching between the two structures
and reduce losses at high energy
REASONS OF THE CAPTURE REDUCTION IN LIGHT35
parameter
SCDTL35
s
Number of cells/tank
Intertank distance at 35 MeV
LIGHT35
(TERA DESIGN)
-18°
-13°
6 (i.e 6 ) 18 (i.e 9 )
3.5
4.5
With some modifications in the part at fixed energy (35-100 MeV) it is
possible (as it will be shown in the next slides) to increase the
longitudinal and transverse acceptance of LIGHT35, so improving
the matching between the two structures and avoiding losses at
high energy without getting a longer structure (inter-tank distance in
the last two modules from 2.5  to 1.5 )
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LIGHT35 ORIGINAL
module
1
2
3
4
5
6
7
8
T O T AL
phis
n. tank
°
-13
4
-13, -14
4
-14
4
-14
3
-14,-15
3
-15
3
-15
3
-16
3
27
n c ell
72
72
72
54
54
54
54
54
486
E nerg y E nerg y g ain L eng th P eak P ower
MeV
MeV
m
MW
53
18
1.45
6.70
75
22
1.74
6.98
100
25
2.01
7.00
124
24
1.54
6.52
150
26
1.68
6.66
177
27
1.80
6.54
205
28
1.92
6.51
235
30
2.02
6.57
200
14.16
53.47
LIGHT35 MODIFIED (three more tanks, but no greater final length)
module
-
phis
°
n. tank
-
1
2
3
4
5
6
7
8
TOTAL
-16
-16
-15
-15
-15
-15
-15
-15
-
5
5
5
3
3
3
3
3
30
n c ell
-
E nerg y
MeV
70
52
75
74
75
100
54
124
54
150
54
177
54
205
54
235
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-
E nerg y g ain
MeV
L eng th
m
17
1.46
22
1.90
26
2.08
24
1.54
26
1.68
27
1.80
28
1.75
30
1.84
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200
14.06
P eak P ower
MW
6.57
6.98
7.02
6.57
6.69
6.53
6.57
6.71
53.64
NEW START TO END FROM 7 to 235 MeV
PL7 at 428 MHz
 LEBT 29 cm long
 SCDTL35
 LIGHT35 (modified)
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LAYOUT:
30%
SCDTL35
LIGHT35
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20%
NEW START TO END FROM 7 to 235 MeV
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Accepted SCDTL35 output coordinates by LIGHT35
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LIGHT35 output beam: transmission from the
injector=30%
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START TO END
7 - 235 MeV:
EMITTANCE
Final un-normalized
RMS emittance:
0.25  mm-mrad
Final normalized
RMS emittance:
0.2  mm-mrad
ADAM meeting Geneve, 09-02-2010
CONCLUSIONS
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A SCDTL structure up to 35 MeV with a length <5.4 m to be used as the
first part of ERHA linac has been designed: a prototype of the first two
modules up to 17.5 MeV is under realization in the framework of ISPAN
Project
the transverse emittance of the PL7 output beam is inside the
transverse acceptance of SCDTL. The losses are due to longitudinal
mismatching due to the jump of RF frequencies
the longitudinal capture can be improved passing from 425 MHz to 428
MHz for the PL7 linac (to be discussed in the next contacts with
ACCSYS)
A proper revision of the LIGHT35 structure design allows to optimize
the matching between the low and high energy parts of the linac,
bringing the total transmission (in absence of errors) to 30% (near to the
typical values of captures in medical electron linacs) and reducing
losses at high energy
The total length from the injector output from 7 to 235 MeV is  20 m
ADAM meeting Geneve, 09-02-2010
ADDENDUM: SCDTL35 drawings
ADAM meeting Geneve, 09-02-2010
ADDENDUM: SCDTL35 drawings
ADAM meeting Geneve, 09-02-2010