EMMA Design and Construction

1
EMMA Design and Construction

• Bruno Muratori
• STFC, Daresbury Laboratory

21/01/09
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The EMMA Project

• EMMA (Electron Machine with Many Applications) is
  a design for a non-scaling FFAG the worlds
  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)

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INJECTION LINE ALICE to EMMA
ALICE
Vacuum valve
Tomography Section Screens x 3 (emittance
measurement)
SRS Quadrupoles x 3
Emittance measurement
Screen
Wall Current Monitor
SRS Quadrupoles x 2
Vacuum valve
Current measurement
Screen
Screen Vert. Slit
EMMA Ring
Beam Direction
BPM Position measurement
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

Ion Pump
New Dipoles x 2 (33) BPMs at dipole
entrance Position measurement
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Diagnostics injection line

• OTR Screen in ALICE before extraction dipole
• BPMs _at_ 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

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ALICE to EMMA injection line (2)
Tomography diagnostics also used to better
control beam
All matches achieved to good accuracy
wyaiwyg what you ask is what you get
Different match for all energies (10-20 MeV)
Twiss parameters and dispersion and its
derivative are different for every energy and
have to be precise
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EMMA Ring
IOT Racks (3)
Waveguide distribution
Injection Septum 65
Kicker
Kicker
Septum Power Supply
Wall Current Monitor
Wire Scanner
Kicker Power Supplies
Cavities x 19
Extraction Septum 70
Screen
Kicker
Screen
Kicker
Septum Power Supply
D Quadrupole x 42 F Quadrupole x 42
Kicker Power Supplies
Wire Scanner
BPM x 82
16 Vertical Correctors
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6 CELL Girder Assembly
Location for diagnostics
F Magnet
Cavity
D Magnet
Ion Pump
Girder
Beam direction
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2 Cell Section (standard vacuum chamber)
Standard vacuum chamber per 2 cells
Bellows
Field clamp plates
BPM 2 per cell
Beam direction
Vertical Corrector
QD
QF
Cavity
Location for diagnostic screen and vacuum pumping
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Injection Extraction (1)
Screen
Septum
Cavity
Cavity
Kicker
Kicker
Injection
Injection scheme shown Extraction is Kicker,
Kicker, Septum arrangement
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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

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EMMA Kicker Magnet Fast Switching

• 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

Applied Pulse Power Collaboration Design and
construction of thyristor prototype units using
magnetic switching and Pulse Forming Network
techniques
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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
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Septum Concept
Electrical feedthroughs (conductor path to power
supply requires to be short to reduce inductance)
Translation rotation in-vacuum bearings
0 - 7
Motorised linear actuators external to vacuum
-7 to 15 mm
Vacuum flange Aluminium wire seal
Conductor connections with flexibility to
feedthrough to accommodate septum movement
Pole gap 25 mm

• Complete septum assembly mounted
• from top section of vacuum chamber lid.
• 2 linear actuators provide translation
• and rotation of septum.

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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
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Cavity Design
110 mm
Cavity machined form 3 pieces and EB welded at 2
locations
Input coupling loop
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
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Diagnostics /Extraction line
spectrometer dipole
ALICE
SRS quadrupoles
EMMA
New quadrupoles
TD Cavity
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NEW DIAGNOSTICS BEAMLINE LAYOUT
Spectrometer BPM _at_ dipole entrance Screen Faraday
Cup
Extracted momentum
Screen x 3 Tomography Section
SRS Quadrupoles x 6
New Quadrupoles x 4
Emittance measurement
Screen Vert. Slit
E-O Monitor
Wall Current Monitor
Current measurement
Longitudinal profile
BPM Valve
Location for Transverse Deflecting Cavity (NOT IN
BUDGET)
Screen
ALICE
New Dipoles (43) BPMs at dipole entrance
New Quadrupoles x 4
Position measurement
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Diagnostic line
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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

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TDC Resolution (1)

• In absence of quadrupoles resolution increases
  with distance (L) from TDC to screen

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TDC Resolution (2)

• 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

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Transverse deflecting cavity (1)

• Transfer Matrix to screen gives

ßd deflector, ßs screen

• Want R12 big ? sin?? 1, ßs fixed ? make ßd
  large

• Transverse displacement on screen is

• Beam size on the screen

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Transverse deflecting cavity (2)
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Transverse deflecting cavity (3)

• Reverse of formula gives requirement of cavity
  voltage
• Take ?µ 65 and f 0
• For streaked bunch to be comparable to
  un-streaked bunch
• ßx,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 _at_ 1.3 GHz
• Equality gives a streaked beam which is v2 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

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Measurements with TDC

• Slice emittance transverse profiles given by
• knowledge of R12 from TDC to screen
• one dimension on screen gives slice emittance
• other dimension gives bunch length
• Slice energy spread given by
• streaked beam and spectrometer

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Milestones

• ALICE shutdown (Cable management installation) 25
  Oct 21 Nov 2008 1 month
• Diamond drilling of ALICE wall, cable tray
  installation
• 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

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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

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Acknowledgements

• All the EMMA team
• Internal staff
• Collaborators