Beam Dynamics in LINACS: Advanced 2 - Paolo Puggioni

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16 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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A short course:
BEAM DYNAMICS IN LINACS
FOR HADRON THERAPY
1‐Introduction to Beam Dynamics and RF design
2‐Beam Dynamics in LINACS Basic
3‐Beam Dynamics in LINACS Advanced I: Energy modulation
4‐Beam Dynamics in LINACS Advanced II: 
‐treatment requirements on beam parameters
‐beam dynamics requirement on RF and mechanics
‐mechanical tolerances
‐RF tolerances
‐focusing with external magnets and foils (Adriano?!)
5‐DESIGN and LINAC tutorial
TOPICS:
Paolo Puggioni
LEC 4 –BD adv 2
Paolo Puggioni
TREATMENT REQUIREMENTS
LEC 4 –BD adv 2
-Longitudinal plane: Energy dispersion
monochromatic beam
RANGE STRAGGLING
-Transversal planeLATERAL STRAGGLING
~0.5 cm
Quadrupoles before the gantry
DR/R ~0.012
DR/R ~1.8 DE/E
Achromaticity of the beam:
DE ~
5 Mev @ 230 MeV
1.6 Mev @ 70 MeV
Simulations:
DR~13 mm @ 230 MeV
DR~1.6 mm @ 70 MeV
Paolo Puggioni
TRANSVERSE DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Transverse dynamicsPMQ:-transversal misalignment
-rotation angle
-tilts
-gradient error
-longitudinal misalignment
TANK:-transversal misalignment
-tilts
Paolo Puggioni
PMQ ERRORS
LEC 4 –BD adv 2
transversal
misalignment
rotation angle
tilts
longitudinal
Paolo Puggioni
PMQ ERRORS
LEC 4 –BD adv 2
transversal
misalignment
rotation angle
tilts
longitudinal
gradient
< 2%
< 1 mm ?
2-3 deg?
Agreement with: S.Nath BEAM DYNAMICS and ERROR SIMULATIONS, SNS Linac, 2000
Paolo Puggioni
TRANSVERSE DYNAMICS TANK ERRORS
LEC 4 –BD adv 2
Transverse misalignment
Tank tilts
Paolo Puggioni
TRANSVERSE DYNAMICS: SUMMARY
LEC 4 –BD adv 2
PMQs transversal misalignment < 0.1 mm
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
mechanics
power RF
RF response
of the accelerator
distance between tanksRF phase errors
power stability
Field non Uniformity
Tank Average non Uniformity
If the conditions are not satisfied, particles are NOT lost,
but exit with the wrong energy!
E (MeV)
E (MeV)
energy spread
mean value
small errors
big errors
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
mechanicsdistance between tanks
Lit
= (2n+1)boutl/2 + d
jout
∫j
in
@ 3GHz: 0.1 mm 0.5deg
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
mechanicsdistance between tanks
ΔW (MeV)0.1 mm0.5 mm1 mm
Nominal230.045230.045230.045
Mean ±Std dev230.05 ±0.06230.08 ±0.26230.04 ±0.37
min229.86229.33228.04
max230.22230.79
230.95
0
2
4
6
8
10
12
228.03
228.15
228.27
228.39
228.51
228.63
228.75
228.87
228.99
229.11
229.23
229.35
229.47
229.59
229.71
229.83
229.95
230.07
230.19
230.31
230.43
230.55
230.67
230.79
230.91
Frequency
ΔW (MeV)
1 mm
Mean value of energyEnergy spread
< ? 5 MeV @ 230 MeV
< ? 1.6 MeV @ 70 MeV
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Power RFPhase errors
ΔW (MeV)
0.5 deg1 deg2 deg3 deg4 deg5 deg10 deg
Nominal230.045230.045230.045230.045230.045230.045230.045
Mean ±Std
dev
230.05 ±
0.04
230.05 ±
0.08
230.05 ±
0.16
230.057 ±
0.237
230.064 ±
0.298
230.066 ±
0.345
229.893 ±
0.535
min229.92229.8229.55229.357229.22229.021227.03
max230.19230.32230.58230.8230.856230.903231.296
0
2
4
6
8
10
12
14
229.016
229.111
229.206
229.301
229.396
229.491
229.586
229.681
229.776
229.871
229.966
230.061
230.156
230.251
230.346
230.441
230.536
230.631
230.726
230.821
More
Frequency
ΔW (MeV)
5 deg
Mean value of energyEnergy spread
< ? 5 MeV @ 230 MeV
< ? 1.6 MeV @ 70 MeV
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Power RFPower stabilityRANGE STRAGGLING
AIM: Energy errors within 0.0025
(mean energy error –NOT SPREAD! –better than 0.5 MeV (1mm range) @ 230 MeV)
Power stability within 0.005
;;
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Tank Average
Non Uniformity
RF response
of the accelerator
50% split
Z1
Z2

shunt impedance
≤0.3%
< 3% (to be checked!)
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Tank Average
Non Uniformity
RF response
of the accelerator
50% split
∫1
Bridge coupler mistuning:
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Tank Average
Non Uniformity:
THE CAUSES
RF response
of the accelerator
Bridge coupler mistuning:
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
RF response
of the accelerator
Bridge coupler mistuning:
BCC error < 2 MHz!
Tank Average
Non Uniformity:
THE REQUIREMENTS
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Field non Uniformity in the cells
RF response
of the accelerator
AC error: 5MHz
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Field non Uniformity in the cells
RF response
of the accelerator
ΔW (MeV)0.50%1%2%
Nominal230.045230.045230.045
Mean ±Std dev230.044 ±0.002230.044 ±0.004230.04 ±0.01
min230.037230.032230.02
max230.052230.057
230.07
Not important effect
Los Alamos studies: errors up to 10% !!!
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Field non Uniformity in the cells:
THE CAUSES: CELLS MISTUNING
RF response
of the accelerator
Err CC (MHz)
Err AC (MHz)
Not a problem < 10%
Paolo Puggioni
LONGITUDINAL DYNAMICS REQUIREMENTS
LEC 4 –BD adv 2
Field non Uniformity in the cells:
THE CAUSES: BC MISTUNING
RF response
of the accelerator
Not a problem < 10%
Paolo Puggioni
LONGITUDINAL DYNAMICS SUMMARY
LEC 4 –BD adv 2
Intertankdistance errors: < 0.1mm
Phase error: < 1 deg ?
Power stability: < 0.005
Tank average non Uniformity
< 3%
50 % split between two modules!
BCC errors < 2 MHz
Field non Uniformity in the cells
< 10%
BAC errors < 5 MHz
AC and CC errors < 5 MHz
EASY!
mechanics
power RF
RF response of the accelerator
Paolo Puggioni
NATURAL QUESTION:
LEC 4 –BD adv 2
Why to tune the cells if the required precision
for the dynamics is about 5 MHz?
AC error: 5MHz
Power efficiency!!!
Paolo Puggioni
Accelerating cells errors:
LEC 4 –BD adv 2
Power efficiency!!!
Err AC (MHz)
Err CC (MHz)
97%
Paolo Puggioni
Bridge coupler AC error:
LEC 4 –BD adv 2
Power efficiency!!!
w BAC (MHz)
w BCC (MHz)
Paolo Puggioni
Summary: frequency errors in the cavities
LEC 4 –BD adv 2
Accelerating cavities:
Coupling cavities:
End cells:
0.5 MHz
4 MHz
0.2 MHz
Errors on the side of
the chain weight more
TANK
Bridge “Accelerating” cavity
Bridge coupling cavity
4 MHz
2 MHz
BRIDGE
COUPLER
Paolo Puggioni
Summary: frequency errors in the cavities
LEC 4 –BD adv 2
Accelerating cavities:
Coupling cavities:
End cells:
0.5 MHz
4 MHz
0.2 MHz
TANK
Bridge “Accelerating” cavity
Bridge coupling cavity
4 MHz
2 MHz
BRIDGE
COUPLER
Power efficiency
Tank average non uniformity
Field non uniformity in the cells
Paolo Puggioni
LEC 4 –BD adv 2
Thank you
-Everybody for the attention (?!)
-Alberto for the help in the energy modulation lecture
-Sara for the error study