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SCDTL study for ERHA. C. Ronsivalle, L. Picardi. 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.

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Scdtl study for erha

SCDTL study for ERHA

C. Ronsivalle, L. Picardi

ADAM meeting Geneve, 09-02-2010


  • 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 TOP-IMPLART 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€)

ADAM meeting Geneve, 09-02-2010


Ispan irraggiamento sperimentale con protoni per modelli cellulari ed animali project
ISPAN (“Irraggiamento Sperimentale con Protoni per modelli cellulari ed Animali”) Project

SCDTL

  • The Project foresees the realization of a test facility at ENEA-Frascati laboratories by using as injector a PL7 425 MHz linear accelerator

ADAM meeting Geneve, 09-02-2010


Outline
Outline cellulari ed Animali”) Project

  • 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 data-December 2009 version)

  • CONCLUSIONS

ADAM meeting Geneve, 09-02-2010


Main design criteria and constraints
Main design criteria and constraints cellulari ed Animali”) Project

  • 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)

ADAM meeting Geneve, 09-02-2010


Scdtl35 layout
SCDTL35 LAYOUT cellulari ed Animali”) Project

Modules 1-2

Modules 3-4

ADAM meeting Geneve, 09-02-2010


Scdtl35 electrical parameters
SCDTL35 ELECTRICAL PARAMETERS cellulari ed Animali”) Project

* Include flat stems and 20% of coupling losses

Total RF power consumption= 6.57 MW

ADAM meeting Geneve, 09-02-2010


Rf efficiency
RF EFFICIENCY cellulari ed Animali”) Project

FLAT stems for an efficient stem cooling

P=1.4 MW

Cylindric stems (diameter=5 mm): no stem cooling

ADAM meeting Geneve, 09-02-2010


THEORETICAL BEAM DYNAMICS PROPERTIES cellulari ed Animali”) Project(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 *DW * El

(100%) (rms) (100%) (rms) (deg) (keV) (deg-MeV)

------------------------------------------------------------------------------

6.6 (100%) 1.1 7.2(100%) 1.2 59° 93.3 5.411

4.4 (90%) 4.8(90%) (at 2998 MHz) (at 2998MHz)

* Half width

ADAM meeting Geneve, 09-02-2010


BEAM DYNAMICS: LINAC CODE RESULTS FOR AN IDEAL MATCHING BETWEEN PL7 AND SCDTL35 (distance from injector=0)

M1 M2 M3 M4

ADAM meeting Geneve, 09-02-2010


  • Input coordinates BETWEEN PL7 AND SCDTL35 (distance from injector=0)

  • Accepted coordinates in the three phase space planes

  • SCDTL35 output beam: transmission=46.3%

ADAM meeting Geneve, 09-02-2010


Beam quality in these conditions emittance
BEAM QUALITY IN THESE CONDITIONS: EMITTANCE BETWEEN PL7 AND SCDTL35 (distance from injector=0)

RMS unnormalized emittance

at 35 MeV:

0.7  mm-mrad

RMS normalized emittance

at 35 MeV:

0.2 mm-mrad

ADAM meeting Geneve, 09-02-2010


Effect of injector bunch lenghtening on scdtl transmission
EFFECT OF INJECTOR BUNCH LENGHTENING ON SCDTL TRANSMISSION BETWEEN PL7 AND SCDTL35 (distance from injector=0)

Bunch lenghtening due to velocity spread in a drift following the injector

transmission vs distance between injector output and center of the first PMQ on SCDTL: (matched beam on transverse planes)

PL7 425 MHz

PL7 428 MHz

ADAM meeting Geneve, 09-02-2010


MATCHING PL7 at 425 MHz – SCDTL35 (3 EMQs in a LEBT BETWEEN PL7 AND SCDTL35 (distance from injector=0)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

ADAM meeting Geneve, 09-02-2010


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

ADAM meeting Geneve, 09-02-2010

Y-envelope


Linac code output in these conditions
LINAC code output in these conditions LEBT before the PMQ at the SCDTL entrance) to be discussed with ACCSYS

  • Accepted PL7 output coordinates in the three phase space planes

  • SCDTL35 output: beam transmission=33.7%

ADAM meeting Geneve, 09-02-2010


Tstep code losses distribution in scdtl tanks and average energy of lost particles
TSTEP code: LOSSES DISTRIBUTION IN SCDTL TANKS AND AVERAGE ENERGY OF LOST PARTICLES

ADAM meeting Geneve, 09-02-2010


Tstep code losses distribution in terms of power
TSTEP code: LOSSES DISTRIBUTION IN TERMS OF POWER ENERGY OF LOST PARTICLES

Plot normalization: injected current from PL7=1 A

ADAM meeting Geneve, 09-02-2010


Errors and tolerances study
ERRORS AND TOLERANCES STUDY ENERGY OF LOST PARTICLES

ADAM meeting Geneve, 09-02-2010


Errors and tolerances pmqs
ERRORS AND TOLERANCES: PMQs ENERGY OF LOST PARTICLES

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

ADAM meeting Geneve, 09-02-2010


Errors and tolerances tanks
ERRORS AND TOLERANCES: TANKS ENERGY OF LOST PARTICLES

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

each end of tank is independently displaced (tilt)

ADAM meeting Geneve, 09-02-2010


Errors and tolerances phase shifts
ERRORS AND TOLERANCES: PHASE SHIFTS ENERGY OF LOST PARTICLES

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

ADAM meeting Geneve, 09-02-2010


Errors and tolerances total np 100k nruns 300
ERRORS AND TOLERANCES ENERGY OF LOST PARTICLES (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

ADAM meeting Geneve, 09-02-2010


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%

tolerance on PMQ displacement from 50 m

to 100 m

7-35 MeV

17.5-35 MeV

ADAM meeting Geneve, 09-02-2010


Start to end 7 235 mev
START-TO-END RESPECT TO TOLERANCES (that can be relaxed in the last two modules)(7-235 MeV)

ADAM meeting Geneve, 09-02-2010


Start to end scdtl35 light35 retrieved from degiovanni design data december 2009
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.

ADAM meeting Geneve, 09-02-2010


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 LIGHT35

(TERA DESIGN)

s -18° -13°

Number of cells/tank 6 (i.e 6 ) 18 (i.e 9 )

Intertank distance at 35 MeV 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 )

ADAM meeting Geneve, 09-02-2010


LIGHT35 ORIGINAL matching between the two structures and reduce losses at high energy

LIGHT35 MODIFIED (three more tanks, but no greater final length)

ADAM meeting Geneve, 09-02-2010


New start to end from 7 to 235 mev
NEW START TO END FROM 7 to 235 MeV matching between the two structures and reduce losses at high energy

  • PL7 at 428 MHz

  • LEBT 29 cm long

  • SCDTL35

  • LIGHT35 (modified)

LAYOUT:

30%

20%

SCDTL35

LIGHT35

ADAM meeting Geneve, 09-02-2010


New start to end from 7 to 235 mev1
NEW START TO END FROM 7 to 235 MeV matching between the two structures and reduce losses at high energy

  • Accepted SCDTL35 output coordinates by LIGHT35

  • LIGHT35 output beam: transmission from the injector=30%

ADAM meeting Geneve, 09-02-2010


Start to end 7 235 mev emittance
START TO END 7 - 235 MeV: EMITTANCE matching between the two structures and reduce losses at high energy

Final un-normalized

RMS emittance:

0.25  mm-mrad

Final normalized

RMS emittance:

0.2  mm-mrad

ADAM meeting Geneve, 09-02-2010


Conclusions
CONCLUSIONS matching between the two structures and reduce losses at high energy

  • 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
ADDENDUM: SCDTL35 drawings matching between the two structures and reduce losses at high energy

ADAM meeting Geneve, 09-02-2010


Addendum scdtl35 drawings1
ADDENDUM: SCDTL35 drawings matching between the two structures and reduce losses at high energy

ADAM meeting Geneve, 09-02-2010


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