status of the top-implart proton linac p. nenzi 1, f. ambrosini 3, a. ampollini 1, g. bazzano 1, f....
TRANSCRIPT
International Particle Accelerator Conference6th
May 3-8, 2015 Richmond, VA, USA
STATUS OF THE TOP-IMPLART PROTON LINACP. Nenzi1, F. Ambrosini3, A. Ampollini1, G. Bazzano1, F. Marracino1,
L. Picardi1, C. Ronsivalle1, C. Snels2, V. Surrenti1, M. Vadrucci1
1ENEA Frascati Research Center, Frascati, Italy, 2ENEA Casaccia, Roma, Italy, 3Università «La Sapienza», Roma, Italy
AbstractIn this work we present the latest update on the construction of the TOP-IMPLART proton LINAC at the ENEA C.R. Frascati Accelerators Laboratory. TOP- IMPLART is a 150 MeV proton accelerator for protontherapy applications funded by Regione Lazio (Italy). We have successfully commissioned the first 3GHz LINAC structure reaching the energy of 11.6 MeV (from 7 MeV), demonstrating the first proton acceleration in a SCDTL structures at this energy. The second SCDTL LINAC has been tuned and brazed and in delivery to the installation site, the third one is under construction.
SCDTL-1
Conclusion: The medium energy section of the TOP-IMPLART accelerator is under construction at the ENEA Frascati. The first two structures have been completed. The first one is routinely used for experimentation. The second one is going to be delivered for installation and commissioning. The third structure has been simulated and the drawings are under finalization. The design of the fourth structure will start soon.
SCDTL-2 SCDTL-3
The TOP-IMPLART LINACat ENEA-Frascati
Experimental vertical line
7 MeV Injector: Hitachi-AccSys PL7 Model
MEDIUM ENERGY PART (7-35 MeV)
under development
0
5
10
15
20
25
30
35
40
45
100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850
Trans
mitte
d cur
rent
(m
A)
Aluminium thickness (mA)
measurements RF off
measurements RF on
SRIM 11.63 MeV
SRIM 7 MeV
0
20
40
60
80
100
120
0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6
Acce
lera
ted
char
ge n
orm
aliz
ed
to m
axim
um v
alue
(%)
Power (MW)
Simulation
Measurements
Computed energy spectrum at SCDTL-1 exit
Energy measurement from range in Aluminium
Transmitted charge after 700 µm Al vs RF Power
Behaviour under pulse operation
0 0.2 0.4 0.6 0.8 12.96
2.97
2.98
2.99
3
3.01
3.02
3.03
3.04
phi (pi units)
Fre
quen
cy(G
Hz)
SCDTL Module 3
w1(GHz)= 3.00574
w2(GHz)= 2.99380
k= 0.01933
k1= -0.00649k2= 0.00257
Stop Band(GHz)= 0.00162
The TOP-IMPLART (Intensity Modulated Proton Linear Accelerator for RadioTherapy) accelerator is a proton LINAC designed for medical applications. The accelerator, when completed, will deliver a proton beam with energy variable in the 85 MeV to 150MeV range. TOP-IMPLART accelerator consists of: a commercial injector (up to 7 MeV), the PL7 model produced by Hitachi-AccSys (425 MHz, 100 μs pulse, 100 Hz pulse repetition frequency, maximum), a medium energy section (7 MeV to 35 MeV), consisting of 4 SCDTL structures (2997.92 MHz, 4 μs pulse), a high- energy section (35 MeV to 150 MeV), consisting of 12 CCL structures (2997.92 MHz, 4 μs pulse). The injector section is connected to the first SCTDL structure by a LEBT consisting of a first quadrupole doublet followed by a deflecting magnet and a second quadrupole doublet. The LEBT is meant to focus the beam to fit the SCDTL pipe that has 4 mm diameter, whereas the injector pipe is 35mm diameter. The deflecting magnet is used to deliver the proton beam to a vertical beam-line used in radiobiology experiments.
Low Energy Beam Transfer Line with the vertical line in the middle
The SCDTL based medium energy section is actually driven by a TH2090 15MW klystron tube installed in a pulse forming network modulator. Klystron RF signal is generated by a DDS unit and amplified by an AM10 solid state power amplifier.
The system will be upgraded with a TH2157A (10MW) klystron and a solid state modulator to improve pulse to pulse amplitude variability (<0.1%).
Parameter Value
Length 1.1 m
# of tanks 9
# cells/tanks 4
RF power 1.3 MW
Status Operation
Parameter Value
Length 1.1 m
# of tanks 7
# cells/tanks 5
RF power 1.6 MW
Status Tuning
Smith Chart (measured) showing the overcoupling of the structure. The value of β=1 can be obtained on the fully brazed structure by adding stubs in the RF feed. This procedure allows to compensate changes that may occur during the finalization of the structure.
Resonance modes of the SCDTL-2 structure excited from the central tank (in reflection).
Parameter Value
Length 1.35 m# of tanks 5# cells/tanks 6RF power 2 MW
StatusUnder
constructionInstallation is foreseen in September 2015
Modal dispersion of SCDTL-3
Computed longitudinal electric field on axis in the π/2 mode ( 2998.5 MHz, E0=15.62 MV/m).
Numerical calculations highlight that, with increase of tanks length, higher order modes move towards the operation band. In particular this is true for the transverse mode TE111, which is directed in the orthogonal direction to the stem axis. To move this mode away from the operation band, post couplers are required in the two final tanks.
3000
3020
3040
3060
3080
3100
3120
3140
115 120 125 130 135 140 145
MHz
Tank length(mm)
Modo fondamentale (TM010)
Primo modo superiore
Fundamental mode
First higher order mode
2700
2750
2800
2850
2900
2950
3000
3050
0 0.5 1 1.5 2 2.5
Freq
uenz
a m
odi T
E (M
Hz)
penetrazione post (cm)Post penetration (cm)
TE m
odes
freq
uenc
y (M
Hz)
Frequencies of the fundamental and first higher order mode at increasing tank length.
Post penetration into the cavity moves away the frequency of the TE higher orders modes from the operation band.