CEA /DSM Dapnia Linear Collider and other HEP Accelerator R&D O. Napoly CEA-Saclay, DAPNIA.
Frascati, 28 Maggio 2003 Accelerator Physics and Design Working Group Summary 2/2 O. Napoly.
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Transcript of Frascati, 28 Maggio 2003 Accelerator Physics and Design Working Group Summary 2/2 O. Napoly.
Frascati, 28 Maggio 2003
Accelerator Physics and DesignWorking Group
Summary 2/2
O. Napoly
Frascati, 28 Maggio 2003
CEBAF Energy Recovery ExperimentMichael Tiefenback
• GeV scale Energy Recovery demonstration. – Testing the potential of ERLs– Demonstration of high final-to-injection energy ratios -
20:1 and 50:1– Optimized beam transport in large scale recirculating
linacs (320 SC cavities) - RF steering and skew field compensation for accelerated/decelerated beams
56MeV injection
56MeV
/2 phase delay chicane
1L21
2L21
56MeV 556MeV
556MeV1056MeV
556MeV1056MeV
56MeV 556MeV
deceleration
acceleration
deceleration
Frascati, 28 Maggio 2003
0.15
0.10
0.05
0.00
-0.05
-0.10
Vo
lts (
mV
)
4003002001000Time (s)
with ER without ER
Gradient Modulator Drive Signals (SL20 Cavity 8)
Graph Courtesy C. Tennant
CEBAF Energy Recovery ExperimentMichael Tiefenback
rf power measurement - selected cavity at the end of South Linac
Standard arc BPMs go dead with ER beam: - BPM signal at RF fundamental- Decelerated beam is λ/2 delayed from primary beam signals destructively interfere in BPM antennae
Frascati, 28 Maggio 2003
CEBAF Energy Recovery ExperimentMichael Tiefenback
synchrotron light monitor – accelerated/decelerated beams at 556 MeV
Emittance measurements and Halo measurement Beam quality is essentially preserved (80 µA)
500
400
300
200
100
0
35 30 25 20 15 10 5 0
56 MeV Beam
Wire scan at 2L22: X, X-Y, Y
1056 MeV Beam
mm
current
CW Energy Recovery Linac for Next Generation of XFELs
General Thoughts based on TESLA XFEL-TDR
TJNAF: A. Bogacz INFN:INFN: M. Ferrario, L. SerafiniDESY:DESY: D. Proch, J. Sekutowicz, S.
SimrockBNL: I. Ben-ZviLANL: P. ColestockUCLA: J. B. Rosenzweig
TESLA_TTF Meeting Frascati, May 26-28, 2003
Frascati, 28 Maggio 2003
RF
-Gu
n
?B
C I
: 0
.14
GeV
BC
II
: 0.5
0
GeV
BC
III
: 2
.50
GeV
En
= 1
0÷
20
GeV R
~150
m
1.8 km
~3 km
Dump (0.5 MW)
3xSASE 2xUndulators
Possible layout can be very similar to the present pulsed linac
• energy recovery 95%
Frascati, 28 Maggio 2003
0.00
0.25
0.50
0.75
1.00
201816141210
En [GeV]#
bun
ches
/s [
1E6
]
0
5
10
15
20 B
eam
Pea
k Po
wer
[MW
]
# of 1nC bunches/ s
Beam peak power
Any combination of the bunch charge and the spacing of bunches giving nominal current is OK
Example: 1 mA= 1 nC @ spacing 1 µs
Frascati, 28 Maggio 2003
Conclusion
Needed R&D :• cw RF gun• suppression of microphonics• more experience with the
energy recoveryTotal cost without experiments should be < 400 MEurosTotal AC power for Cryoplant + RF < 10 MWBut we will have :
6 x more bunches /s very flexible time structure of the beam.
Frascati, 28 Maggio 2003
* TESLA Meeting - Frascati - 27 May 2003 * TESLA Meeting - Frascati - 27 May 2003 **
Towards a Towards a Superconducting High BrightnessSuperconducting High Brightness
RF PhotoinjectorRF Photoinjector
M. Ferrario, J. B. Rosenzweig, J. Sekutowicz, L. SerafiniM. Ferrario, J. B. Rosenzweig, J. Sekutowicz, L. Serafini
INFN, UCLA, DESYINFN, UCLA, DESY
Frascati, 28 Maggio 2003
Main Questions/ConcernsMain Questions/Concerns
• RF Focusing vs Magnetic RF Focusing vs Magnetic focusing ? focusing ?
• High Peak Field on Cathode ?High Peak Field on Cathode ?
• Cathode Materials and QE ?Cathode Materials and QE ?
• Q degradation due to Magnetic Q degradation due to Magnetic Field ?Field ?
Frascati, 28 Maggio 2003
2 10-5
4 10-5
6 10-5
8 10-5
0.0001
0.00012
0.00014
0.00016
0.00018
0 10 20 30 40 50 60 70
BNL_SCRF_CAT
QE
QE
G [MV/m]
SCRF GUN
Measured
Limited by the available voltageLimited by the available voltage
Measurements at room T Measurements at room T on a dedicated DC on a dedicated DC
systemsystem
Extrapolation to Extrapolation to Higher Field Higher Field
Frascati, 28 Maggio 2003
Splitting Acceleration and Splitting Acceleration and FocusingFocusing
25 cm10 cm
50 cm
• The Solenoid can be placed downstream the cavity The Solenoid can be placed downstream the cavity
• Switching on the solenoid when the cavity is cold Switching on the solenoid when the cavity is cold prevent any trapped magnetic fieldprevent any trapped magnetic field
-20
-10
0
10
20
30
40
50
60
-0.05
0
0.05
0.1
0.15
0.2
0 0.2 0.4 0.6 0.8 1
Ez_[MV/m] Bz_[T]E
z_[M
V/m
]B
z_[T
]
z_[m]
Frascati, 28 Maggio 2003
0
1
2
3
4
5
6
0 5 10 15
HBUNCH.OUT
sigma_x_[mm]enx_[um]
sig
ma
_x_
[mm
]
z_[m]
Q =1 nCQ =1 nC
R =1.5 mmR =1.5 mm
L =20 psL =20 ps
thth = 0.45 mm-mrad = 0.45 mm-mrad
EEpeakpeak = 60 MV/m (Gun) = 60 MV/m (Gun)
EEacc acc = 13 MV/m (Cryo1)= 13 MV/m (Cryo1)
B = 1.9 kG (Solenoid)B = 1.9 kG (Solenoid)
I = 50 AI = 50 A
E = 120 MeVE = 120 MeV
nn = 0.6 mm-mrad = 0.6 mm-mrad
nn
[mm-mrad][mm-mrad]
Z [m]
HOMDYN Simulation
6 MeV6 MeV
3.5 m
scaling laws for Q and Escaling laws for Q and Epeakpeak available available
Progress on Helical Undulator for Polarised Positron Production
Duncan Scott
ASTeC
Daresbury Laboratory
Frascati, 28 Maggio 2003
SC Magnet Undulator Prototype
Prototype Magnet Design for 14mm period: Beam Stay Clear 4mm Helix Diameter 6mm
Frascati, 28 Maggio 2003
Permanent Magnet Undulator Design
• 14mm Period, 4mm Bore “Halbach” undulator • (Klaus Halbach NIM Vol. 187, No1)
• Rotate many rings to create Helical Field
• PPM blocks create Dipole Field
Frascati, 28 Maggio 2003
• Vacuum Problems• TESLA requirements of ~10-8 mbar vacuum CO equivalent• For the SC magnet :
– this can be achieved, as long as the number of photons above 3eV hitting the vessel wall is not greater than 1017 s-1 m-1
• For the Permanent magnet : – theoretical maximum for a 5 m long 4mm bore vacuum pipe is 10-
7mBar – A NEG coated vessel is needed, thought to be feasible although
no-one has ever NEG coated a 4mm diameter tube
• Hope to build two ~20 period prototypes (one of each design) to measure the magnetic field this year
Progress on Helical Undulator for Polarised Positron Production
TESLA Damping Ring: Injection/Extraction Schemes with RF Deflectors
D. Alesini, F. Marcellini
Frascati, 28 Maggio 2003
DR
SEPTUM
RF Defl. Extr.
RF Defl. inj.
VRF Train 1
Train 2
Injection
CTF3-LIKE INJECTION/EXTRACTION SCHEME (simple scheme)
*
TL
TDR
=TL/F
MAX
(deflection angle)
Extr./Inj. bunch
1) If the filling time (F) of the deflectors is less than TDR it is possible to inject or extract the bunches without any gap in the DR filling pattern.
2) should be * depending on the ring optics and septum position. Considering a single RF frequency
/MAX=1-cos(2/F)
Extracted bunches
MAIN LINAC
Extraction
1st train 2nd train
NB/F TL
LINAC TRAIN
Rec. factor
Frascati, 28 Maggio 2003
DEFLECTOR PARAMETERS (/2)6 Deflectors (3 inj. + 3 extr.)
Defl 1 fRF1 = 433*1/ TL = 1284.87 [MHz]Defl 2 fRF2 = 438*1/ TL = 1299.70 [MHz]Defl 3 fRF3 = 443*1/ TL = 1314.54 [MHz]
Total beam deflection = 0.87 [mrad]Deflection defl.1 = 0.29 [mrad]Deflection defl.2 = 0.29 [mrad]Deflection defl.3 = 0.29 [mrad]
P = 9 [MW]L = 0.64 [m]F = 48 [nsec]n. Cells/defl = 11
P = 5.00 [MW]L = 0.86 [m]F = 64 [nsec]n. Cells/defl = 15
MAX = 69 %
3 Frequencies
maximization of MAX in the range [430*1/ TL 450*1/ TL] =1.276 1.335 GHz no bunch length
3 distant freq. case
3 close freq. case
Frascati, 28 Maggio 2003
FINITE BUNCH LENGTH
New optimization procedure:
- to increase 1
- (if possible) to reduce the RF slope over the bunch length
z=6 mm, the same 2 freq. optimized in the previous case give:
1 = 9 %
Extracted bunch
How to avoid the effect of the RF curvature on the extr. bunches
Frascati, 28 Maggio 2003
DEFLECTOR PARAMETERS (/2)6 Deflectors (3 inj. + 3 extr.)
Defl 1 fRF1 = 444*1/ TL = 1317.51 [MHz]Defl 2 fRF2 = 437*1/ TL = 1296.74 [MHz]Defl 3 fRF3 = 435*1/ TL = 1290.80 [MHz]
Total beam deflection = 1.05 [mrad]Deflection defl.1 = 0.35 [mrad]Deflection defl.2 = 0.35 [mrad]Deflection defl.3 = 0.35 [mrad]
P = 9 [MW]L = 0.78 [m]F = 58 [nsec]n. Cells/defl = 13
P = 5.00 [MW]L = 1.04 [m]F = 77 [nsec]n. Cells/defl = 18
3 Frequencies
1 = 57 %
maximization of 1 in the range [430*1/ TL 450*1/ TL] =1.276 1.335 GHz
bunch length z=6 mm
3 distant freq. case
3 close freq. case
Frascati, 28 Maggio 2003
F=100 LDR2.85 Km maximization of 1
in the range [430*1/ TL 450*1/ TL] =1.276 1.335 GHz
bunch length z=2 mm
P = 9 [MW]L = 1.6 [m]F = 119 [nsec]n. Cells/defl = 28
P = 5.00 [MW]L = 2.15 [m]F = 160 [nsec]n. Cells/defl = 37
DEFLECTOR PARAMETERS (/2)6 Deflectors (3 inj. + 3 extr.)
Defl 1 fRF1 = 447*1/ TL = 1326.41 [MHz]Defl 2 fRF2 = 440*1/ TL = 1305.64 [MHz]Defl 3 fRF3 = 436*1/ TL = 1293.77 [MHz]
Total beam deflection = 2.16 [mrad]Deflection defl.1 = 0.72 [mrad]Deflection defl.2 = 0.72 [mrad]Deflection defl.3 = 0.72 [mrad]
1 = 28 %
3 distant freq.
Frascati, 28 Maggio 2003
OUR EXPERIENCE WITH RF DEFLECTOR FOR CTF3
1. STUDY AND NUMERICAL SIMULATIONS
2. MECHANICAL DRAWING
3. CONSTRUCTION
4. MEASUREMENTS
1st turn - 1st bunch train from linac
2nd turn
3rd turn
4th turn
Frascati, 28 Maggio 2003
20 30 40 50 60 700
0.5
1
1.5
2
2.5
3
3.5
a [mm]
de
flect
or
len
gth
(L
) [m
]
P=5 MWP=9 MW
20 30 40 50 60 7050
100
150
200
250
300
a [mm]
Fill
ing
tim
e (
f) [n
sec]
20 30 40 50 60 700
5
10
15
a [mm]Dis
sip
ate
d p
ow
er
pe
r u
nit
len
gth
(d
P/d
z) [k
W/m
] @
5 H
z, 1
ms
RF
pu
lse
20 30 40 50 60 70-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
a [mm]
kick
3MH
z/kic
k nom
MODE /2; DEFLECTION=0.5 mrad; fRF
=1.3 GHz; DISK THICKNESS=11.53 mm; CELL LENGTH=57.65 mm
/2 MODE
Deflection = 0.5 mrad
fRF = 1.3 GHz
Disk thickness = 11.53 mm
Cell length = 57.65 mm
Frascati, 28 Maggio 2003
Module III Module II
OFF
q = 3.5 nCfb = 2.25 MHzTp = 780 s
Agilent E8563Espectrum analyser
zero span
HOM 2
HOM 1
Att10 dB
GPIB
Spectrum analyser
Beam
• used as aparametric bandpass filter:– central frequency– resolution bandwidth
• signals in time domain
ON
Beam Position Measurements in TTF Cavities using Dipole Higher Order Modes
G. Devanz, O. Napoly, CEA, Gif-sur-YvetteA. Gössel, S. Schreiber, M. Wendt, DESY, Hamburg
Frascati, 28 Maggio 2003
Dipole mode measurements
-10
-8
-6
-4
-2
0
2
4
6
8
10
0 1 2 3 4 5 6 7 8 9 10
cavity index
bea
m p
osi
tio
n (
mm
)
2 positions computed using 2 modes with the same beam
High gradient in cavities (~ 20 MV/m) orbit is expected to cross ACC1 module axis if entering at an offset
Scattering Parameter Calculationfor the 2x7 Superstructure
TESLA Collaboration Meeting
INFN Frascati May 26-28, 2003
Karsten Rothemund, Dirk Hecht, Ulla van Rienen
Frascati, 28 Maggio 2003
2x7-Superstructure
-e
7 Cell TESLA Cavity
HOM-Coupler
Input-Coupler
Images: I.Ibendorf
Radius Adapter
Frascati, 28 Maggio 2003
HOM-Coupler (HOM 2 + HOM 3)
HOM 2
HOM 2HOM 3 HOM 1
Input
rotate
HOM 3
shift planes
27.4 mm27.4 mm
Frascati, 28 Maggio 2003
7 Cell TESLA Cavity
f=1.5-3.0 GHz
TE11
TM01
TE21
Plot: MWS, simulation: MAFIA, 2D, time domain
f/GHz
|S..|/dB
f/GHz
|S..|/dB |S..|/dB
Frascati, 28 Maggio 2003
CSC-Computation
Calculation of overall S-matrixopen ports: beam pipe, 3x HOM-, 1x Input-coupler
1500 values computed in 1.5-3 GHz frequency range shown here: 2.46-2.58 GHz (3rd dipole passband)
481 frequency-points + interpolation
S-valuesof 7-cell cavity
f/GHz
|S..|/dB
Frascati, 28 Maggio 2003
Results
Coupling between HOM1 and HOM2 to beam pipe modes
HOM1
HOM2
downstream beam pipe
upstream beam pipe
f/GHz
|S..|/dB
f/GHz
|S..|/dB
Frascati, 28 Maggio 2003
Summary
• S-parameter of 2x7 TESLA-Superstructure have been calculated (an open structure) with CSC• 5 modes have been considered in the structure• S-parameter of subsections were computed with
• CST-MicrowaveStudioTM (coupler sections, 3D)• MAFIA (TESLA cavity, 2D-rz-geometry)• analytically (shifting planes, rotation)
• some exemplary coupling parameters have been presented• computation times for S-parameters of subsections in order of days• additional computation times whole structure then in the order of minutes• parameter tuning (e.g. rotation angles, distances) possible
Start-to-End Simulationsfor the
TESLA LC
A Status Report
Nick WalkerDESY
TESLA collaboration Meeting, Frascati, 26-28th May 2003
Frascati, 28 Maggio 2003
Ballistic Alignment
bi qi
Lb
quads effectively aligned to ballistic reference
angle = i
ref. line
with BPM noise
62
Frascati, 28 Maggio 2003
New Simulations usingPLACET and MERLIN
• 14 quads per bin (7 cells, = 7/3)• RMS Errors:
– quad offsets: 300 m– cavity offsets: 300 m– cavity tilts: 300 rad– BPM offsets: 200 m– BPM resolution: 10 m– CM offsets: 200 m– initial beam jitter: 1y (~10 m)
• New transverse wakefield included(~30% reduction from TDR)[Zagorodnov and Weiland, PAC2003]
wrt CM axis
Frascati, 28 Maggio 2003
Ballistic Alignment
Less sensitive to • model errors• beam jitter
average over 100 seeds
Frascati, 28 Maggio 2003
Ballistic Alignment
average over 100 seeds
We can tune out linear y and y’ correlation using bumps or dispersion correction in BDS
Frascati, 28 Maggio 2003
Beam-Beam Issues
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
20 22 24 26 28 30
L [1
034
cm-2
s-1]
y [nm ]
L1off
Langapprox.
optimise beam-beam offset and angle
OK for ‘static’ effect
D. Schulte. PAC03, RPAB004
Frascati, 28 Maggio 2003
Simulating the Dynamic Effect
Realistic simulated ‘bunches’ at IPRealistic simulated ‘bunches’ at IP– linac (PLACET, D.Schulte)linac (PLACET, D.Schulte)– BDS (MERLIN, N. Walker)BDS (MERLIN, N. Walker)– IP (GUINEAPIG, D. Schulte)IP (GUINEAPIG, D. Schulte)– FFBK (SIMULINK, G. White)FFBK (SIMULINK, G. White)
bunch trains simulated with realistic bunch trains simulated with realistic errors, including ground motion and errors, including ground motion and vibrationvibration
LINAC BDS IR BDSIR
IP FFBK
All ‘bolted’ together within a MATLAB framework by Glen White (QMC)
Frascati, 28 Maggio 2003
Simulating the Dynamic Effect
IP beam angle IP beam offset
Frascati, 28 Maggio 2003
Simulating the Dynamic Effect
21034 cm2s1
Only 1 seed: need to run many seeds to gain statistics!
NEW DESIGN OF THE TESLA INTERACTION REGION WITH l* = 5 m
O. Napoly, J. Payet CEA/DSM/DAPNIA/SACM
Advantages from the detector point-of-view
– Larger forward acceptance at low angles
– Final doublet moved out of the calorimeter
less e.m. showers in the detector
– Lighter Tungsten-mask and simpler support
Frascati, 28 Maggio 2003
0
100
200
300
0 100 200 300 400 500
0,00
0,05
0,10
0,15
hx
hx (m)
bx1/2
bz1/2
s (m)
b1/2 (m1/2)
SF1, SD1
SF
SD2
SF
Beamstrahlung Dump
NLC-like Optics
0.73 6.6 10-14
x (m.rad)L/L0 @ 0,4%FFS
TDR 3 0.0
l* (m) h 'x (mrad)
NLC-like 5 10.0 0.86 5.6 10-14
Frascati, 28 Maggio 2003
Simulating the Extraction Line
Part of the extraction line included in BRAHMS:
Shadow:• Distance from IP: 45m• 2m long• 5mm thick• 7mm vertical distance from nominal beam (~156 µrad)• Copper
Septum Blade:• Distance from IP: 47m• 16m long• 5mm thick• ~7mm vertical distance from nominal beam• Copper
Frascati, 28 Maggio 2003
Realistic Beam
• Shadow:
Average deposited power: ~15 kW
• Septum blade:
Average deposited power: ~80 W