Download EMMA design and construction

EMMA Design and Construction
Bruno Muratori
STFC, Daresbury Laboratory
21/01/09
The EMMA Project
• EMMA (Electron Machine with Many Applications) is a design for a
non-scaling FFAG – the world’s first
• Collaboration of : BNL, CERN, CI, FNAL, JAI, LPSC Grenoble,
STFC, TRIUMF
• Part of BASROC (British Accelerator Science and Radiation
Oncology Consortium) / CONFORM (COnstruction of a Non-scaling
FFAG for Oncology, Research and Medicine)
• Advantages:
– Linear fixed field magnets: large dynamic aperture
– Cheaper
• Disadvantages:
– Novel longitudinal & transverse dynamics
– Rapid tune variations: multiple resonance crossings
• Many potential applications
– Driver for ADSR, µ acceleration, medical (e.g. PAMELA)
INJECTION LINE ALICE to EMMA
Tomography Section
Screens x 3
(emittance
measurement)
Emittance measurement
SRS Quadrupoles x 2
Vacuum
valve
Screen
EMMA
Ring
SRS Quadrupoles x 3
Screen &
Vert. Slit
•
New Dipole 30°
& BPMs at dipole entrance
Position measurement
New Quadrupoles x 13
Match the probe beam to
the requirements of EMMA
Measure the properties of
the probe beam
ALICE
Screen
Wall Current
Monitor
Current
measurement
BPM
Position
measurement
•
Vacuum
valve
Ion Pump
New Dipoles x 2 (33°)
& BPMs at dipole entrance
Position measurement
Diagnostics – injection line
•
•
•
•
•
OTR Screen in ALICE before extraction dipole
BPMs @ entrance of every dipole in injection line
Straight ahead Faraday cup to measure charge & energy spread
OTR screen in dogleg for bunch length & energy measurement
Tomography section: 60 degrees phase advance per screen with
three screens for projected transverse emittance measurements
and profiles
• Last dispersive section:
– OTR screen & vertical slit in middle of first section together with
– OTR screen in final section for energy and energy spread
measurements
– Vertical steerers for position & angle before ring (to be used
with kickers for steering)
– BPM at entrance of EMMA ring for position before entering
ALICE to EMMA injection line (2)
Tomography
diagnostics also used
to better control
beam
Different match for all
energies (10-20 MeV)
All matches achieved to
good accuracy – wyaiwyg
‘what you ask is what you get’
Twiss parameters and
dispersion and its derivative
are different for every energy
and have to be precise
EMMA Ring
Waveguide distribution
IOT
Racks (3)
Injection
Septum 65°
Kicker
Kicker
Wire Scanner
Extraction
Septum 70°
Screen
Kicker
Wall
Current
Monitor
Septum
Power
Supply
Kicker
Power
Supplies
Cavities
x 19
Screen
Kicker
Septum
Power
Supply
Kicker
Power
Supplies
D Quadrupole x 42
F Quadrupole x 42
Wire Scanner
BPM x 82
16 Vertical
Correctors
6 CELL Girder Assembly
Location for diagnostics
F Magnet
D Magnet
Cavity
Ion
Pump
Girder
2 Cell Section
(standard vacuum chamber)
Field clamp plates
Standard vacuum chamber
per 2 cells
Vertical
Corrector
Bellows
BPM
2 per cell
QD
QF
Cavity
Location for diagnostic screen and
vacuum pumping
Injection & Extraction (1)
Screen
Septum
Cavity
Kicker
Kicker
Injection scheme shown
Extraction is Kicker, Kicker, Septum arrangement
Cavity
Injection and Extraction (2)
•
•
Have to match ‘orbits’ at all energy ranges &
for all settings (10 – 20 MeV)
– Kickers
– Septum rotation & motion
– In-house code (FFEMMAG - Tzenov)
– Vertical & Horizontal steerers in injection
line – also used for painting (3 mm rad
acceptance)
Kickers specified at 0.07 T
EMMA Kicker Magnet Fast Switching
Magnet length
0.1m
Field at 10MeV (Injection)
0.035T
Field at 20MeV (Extraction)
0.07T
Magnet Inductance
0.25H
Lead Inductance
0.16H
Peak Current at 10/20MeV
1.3kA
Peak Voltage at Magnet
14kV
Peak Voltage at Power
Supply
23kV
Rise / Fall Time
35nS
Jitter pulse to pulse
>2nS
Pulse Waveform
Half Sinewave
Applied Pulse Power Collaboration
Design and construction of thyristor prototype units using
magnetic switching and Pulse Forming Network techniques
Kicker Magnet Power Supply parameters are directly
affected by the compact design and require:
•
Fast rise / fall times 35 nS
•
Rapid changes in current 50kA/S
•
Constraints on Pre and Post Pulses
Injection and Extraction
•
•
•
•
Large angle for injection (65°) and extraction (70°)
very challenging !!
Injection/Extraction scheme required for all energies
10 – 20 MeV, all lattices and all lattice configurations
Minimise stray fields on circulating beam
Space very limited between quadrupole magnet
clamp plates
Final Parameters
25°
Septum Concept
Electrical feedthroughs
(conductor path to power supply requires to be short
to reduce inductance)
0 - 7°
Translation & rotation
in-vacuum bearings
Motorised
linear actuators
external to vacuum
Conductor connections with flexibility
to feedthrough to accommodate
septum movement
• Complete septum assembly mounted
from top section of vacuum chamber lid.
• 2 linear actuators provide translation
and rotation of septum.
Vacuum flange
Aluminium wire seal
Pole gap 25 mm
Septum Design
•
•
•
In house design of septum and vacuum chamber in
progress
Wire eroding of lamination stacks scheduled for
February, steel delivered.
Magnet measurements scheduled for April 09
Section view of septum in vacuum chamber
ISO view of septum with vacuum chamber removed
Plan view of septum in vacuum chamber
Cavity Design
110 mm
Cavity machined form
3 pieces and EB
welded at 2 locations
Parameter
Frequency
1.3 GHz
Input coupling loop
Theoretical Shunt
Impedance
2.3 M
Realistic Shunt
Impedance (80%)
2 M
Qo (Theoretical)
23,000 (23000)
R/Q
100 Ω
Tuning Range
-4 to +1.6 MHz
Accelerating Voltage
120 kV
180 kV
Total Power Required
(Assuming 30% losses
in distribution
90 kW
200 kW
Power required per
cavity
3.6 kW
8.1 kW
Coolant channels
Aperture Ø 40 mm
Probe
EVAC Flange
Capacitive post
tuner
Normal conducting single cell re-entrant
cavity design optimised for high shunt impedance
Value
Diagnostics /
Extraction line
spectrometer dipole
ALICE
SRS quadrupoles
New quadrupoles
TD Cavity
EMMA
NEW DIAGNOSTICS BEAMLINE LAYOUT
SRS Quadrupoles x 6
New Quadrupoles x 4
Screen
& Vert. Slit
BPM &
Valve
Screen x 3
Tomography
Section
Emittance measurement
Spectrometer Extracted momentum
BPM @ dipole entrance
Screen
Faraday Cup
Wall Current Monitor
E-O Monitor
Current measurement
Longitudinal profile
Location for Transverse
Deflecting Cavity
(NOT IN BUDGET)
Screen
ALICE
New Dipoles (43°)
& BPMs at dipole entrance
Position measurement
New Quadrupoles x 4
Diagnostic line
deflecting cavity
tomography
EO
spectrometer
Measurements
• Energy
– First dipole & spectrometer at end with OTRs
• Projected transverse emittance
– Quadrupole scans & tomography 60° phase advance / screen
– Equivalent set-up in injection line for comparisons
• Bunch length
– EO monitor downstream of the tomography section
– No profile information
• Possibility of introducing a transverse deflecting cavity (TDC) to
measure additional bunch properties
TDC Resolution (1)
x
deflecting voltage
0
x
z
σz
screen
deflector
bunch
L
• In absence of quadrupoles resolution increases with distance (L)
from TDC to screen
TDC Resolution (2)
deflecting voltage
x
z
σz
deflector
screen
bunch
• In the presence of interspersed quadrupoles this is not so and we
must take into account of the entire transfer matrix from TDC to
screen – there can be as many quadrupoles as desired
 x1   R11
 ' 
 x1   R21
R12   x0 
 
R22  x0' 
Transverse deflecting cavity (1)
• Transfer Matrix to screen gives
βd – deflector, βs – screen
•
Want R12 big → sinΔψ = 1, βs fixed → make βd large
• Transverse displacement on screen is
• Beam size on the screen
Transverse deflecting cavity (2)
deflecting cavity
tomography
EO
spectrometer
1.6
1.35
0.95
1.13
Δµy = 65°
Δµx = 90°
Transverse deflecting cavity (3)
• Reverse of formula gives requirement of cavity voltage
N
eV0 
pcm0c
 z | sin  cos  |
d

2
• Take Δµ = 65° and φ = 0
• For streaked bunch to be comparable to un-streaked bunch
• βx,y = 9 m at the deflecting cavity therefore we need, assuming an
emmitance degradation to 10 µm and a bunch length of 4 ps
eV0 ≥ 0.23 MV @ 1.3 GHz
• Equality gives a streaked beam which is √2 times un-streaked beam
– only rough idea of requirements
– not enough for ≥ 10 slices (what we would like) → ~ 1 MV ?
– longer bunch lengths / better emittance → lower voltage
Measurements with TDC
• Slice emittance & transverse profiles given by
– knowledge of R12 from TDC to screen
R12   d  s sin 
 x1   R11
 ' 
 x1   R21
– one dimension on screen gives slice emittance
– other dimension gives bunch length
• Slice energy spread given by
– streaked beam and spectrometer
R12   x0 
 
R22  x0' 
Milestones
ALICE shutdown (Cable management installation)
Diamond drilling of ALICE wall, cable tray installation
25 Oct – 21 Nov 2008
1 month
Off line build of modules
Oct 2008 – Jun 2009
9 months
ALICE shutdown
1st Mar – 12th Apr 2009
6 wks
ALICE shutdown
8th Jun – 13th Jul 2009
5 wks
Installation in Accelerator Hall
Mar – Aug 2009
6 months
Test systems in Accelerator Hall
May - Oct 2009
6 months
Injection line and ring complete
31st Oct 09
Commission with electrons starting
Nov 2009
Conclusions
•
•
•
•
All components of injector line ordered (most already at DL)
Order for Extraction / Diagnostic line to go out soon
Very Challenging & exciting project !
Good characterisation of the beam at injection & extraction even
without TDC
• Have good location for TDC should it be used in the future
– Realistic voltage parameters
– Extra beam properties not available with EO
– Currently looking at requirements for TDC with RF engineers
• Aim to be commissioning with electrons at DL in November 2009
• Aim to demonstrate that non scaling FFAG technology works and
compare results with the theoretical studies performed to gain real
experience of operating such accelerators
Acknowledgements
• All the EMMA team
– Internal staff
– Collaborators