Transcript iop-pab-recent-developments-at-diamond

Recent Developments at Diamond
Ian Martin
On behalf of the Diamond Team
Particle Accelerators and Beams Group Meeting
Daresbury Laboratory
10th April 2013
Talk Outline
 Diamond overview
 ARPES beam line
 Reduced coupling operation
 Low alpha with top-up
 Improved current stability
 Improved CSR spectral stability
 Possible future upgrades
 Diamond II options
 Modifying a single cell of existing ring
 Conclusions
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Overview of Diamond
 3rd Generation Synchrotron Light Source
 100 MeV Linac
 3 GeV booster synchrotron (158.4m)
 3 GeV storage ring (561.6m)
 Mix of BM and ID beamlines (long and
standard straight sections)
 Several modes of operation (all top-up):
 Standard (900 bunches / 300mA)
 Hybrid (686 bunches / 300mA + 1 bunch / 3mA)
 Two low-alpha modes (Short x-ray pulse / THz users)
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Overview of Diamond
Operational (15 ID, 4 Dipole)
Optimisation (4 ID)
Construction (4 ID, 2 Dipole)
Design (3 ID, 1 Dipole)
Anticipate all straights assigned
and operational by 2017
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
ARPES (I05) Undulator
For the ARPES beamline, a 5m long APPLE-II device was installed in Nov 2012:
 Long straight section, beta functions larger than standard
 Large tune-shifts in both planes that need to be compensated
 Significant impact on the machine (reduction in dynamic aperture, lifetime)
Photon Energy
Device Period
Number of Periods
Nominal Length
Technology
Minimum Gap
Peak Field
Magnetic Material
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
18-240 eV
140 mm
34
4.995 m
APPLE-II
23.5 mm
0.9T (H) / 0.53T (C) / 0.63T (V)
NdFeB
y (mm)
Dynamic multipole fields compensated using
active shim wires
5
5
0
0
-5
-5
-40
-20
0
x (mm)
20
40
-20
0
x (mm)
20
40
0.2
x (mrad)
0.1
Vertical
Polarisation
Circular
Polarisation
Horizontal
Polarization
Uncorrected
Corrected
Uncorrected
Corrected
Uncorrected
Corrected
Tune Shift (ΔQx / ΔQy)
-0.043 / 0.032
0.003 / 0.003
-0.030 / 0.026
0.005 / 0.004
-0.003 / 0.015
0.008 / 0.008
Beta Beat (x / y)
33% / 32%
3% / 3%
22% / 23%
2% / 2%
2% / 13%
5% / 6%
0
-0.1
-0.2
-40
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Active shim wires
Insertion device
Residual kick
wire current (A)
ARPES (I05) Undulator
Reduced Vertical Emittance
In response to request from Science Division, emittance coupling has been
reduced from 1% to 0.3% for user operation (27 pm.rad to 8 pm.rad)
 Initially confined to machine development periods
 Two week period from 17th October to 1st November 2012
 Standard operational mode since 6th March 2013
Benefits include increased brightness / transverse coherence, smaller spot size
1% coupling
-0.15
-0.1
-0.1
-0.05
-0.05
y (mm)
y (mm)
-0.15
0
0
0.05
0.05
0.1
0.1
0.15
0.15
-0.2
-0.15
-0.1
-0.05
0
0.05
x (mm)
0.1
0.15
0.2
0.3% coupling
-0.2
-0.15
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
-0.1
-0.05
0
0.05
x (mm)
0.1
0.15
0.2
Reduced Vertical Emittance
coupling
lifetime
current
Coupling feedback started
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Reduced Vertical Emittance
Reducing vertical emittance leads to small focus on sample
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Courtesy K. Sawhney
Reduced Vertical Emittance
Reducing vertical emittance leads to higher spatial coherence
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Courtesy K. Sawhney
Low Alpha
The Diamond storage ring is run in a dedicated ‘low alpha’ mode 2-3 times per year
Since Oct 2012, this has been in top-up with hourly injection cycles
Short pulse mode (NANOSCIENCE beamline I06):
 Single bunch for time-resolved science
 Electron bunch length reduced to ~3.5 ps
 Priority on increased single bunch charge over minimum pulse duration (stable!)
THz mode (MIRIAM beamline B22):
 Above bursting threshold to increase CSR gain in THz region
 Priority to extend CSR spectrum towards 100cm-1
Momentum Compaction Factor
Number of bunches
Bunch current
Emittance coupling ratio
Lifetime
Injection efficiency (IDs open)
VRF
Micro-bunching instability threshold (SB)
Bursting threshold (SB)
Short Pulse Mode
-1×10-5
400 + 1
50 µA (93 pC)
0.3%
~20h
30-40%
3.4MV
~30-35 µA
~55-60 µA
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
THz Mode
-4.5×10-6
200
50 µA (93 pC)
1%
~20h
15-20%
3.4MV
~15 µA
~25-30 µA
MIRIAM (B22) Spectrum
03/10/2012
04/10/2012
05/10/2012
Courtesy G. Cinque
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Diamond Upgrade
Starting to take a look at possible options for a future upgrade of the
Diamond lattice*
 Initial criteria
 Reuse tunnel and beamlines
 Reuse as much hardware as possible
 Phased installation (avoid long shutdown)
 Different ‘flavours’ under consideration
 Evolution of 4 Bend Achromat (BA), 5BA, 7BA, ...
 More beamlines vs. lower emittance
*see poster by T. Pulampong
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
4 Bend Achromat
10
8
6
4
Original DBA
Y[m]
2
0
Modified 4BA3.35m
3.35m
-2
4BA
-4
-6
-8
0
5
10
15
X[m]





Magnet arrangement allows 24 additional short straight sections
Natural emittance 275 pm.rad (factor 10 reduction on present lattice)
Magnets and vacuum design challenging (high gradients / small apertures)
Design utilises gradient bending magnets
Harmonic number lowered by 1 to minimize transverse offset for existing
beamlines (circumference reduced from 561.6m to 561.0m)
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
20
5 Bend Achromat
10
8
6
4
Original DBA
Y[m]
2
0
5BA
-2
-4
-6
-8
0
5
10
15
20
X[m]
 Length of existing straight sections reduced to accommodate additional magnets
 Natural emittance 155 pm.rad (factor 17 reduction on present lattice)
 Phase advance across two cells matched to odd integer to help cancel sextupole
driving terms and increase dynamic aperture (~4mm):
  x , cell  4 . 5
  y , cell  2 . 5
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
7 Bend Achromat
10
8
6
4
Original DBA
Y[m]
2
0
7BA
-2
-4
-6
-8
0
5
10
15
20
X[m]
 Natural emittance 45 pm.rad (factor 58 reduction on present lattice)
 Basic design includes dispersion bump between dipoles 1-2 and 6-7 to ease
correction of natural chromaticity
 Maximum sextupole strength factor 2 lower as a result
 Intra-beam scattering places upper limit on beam current that still allows low
emittance to be maintained
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
MBA Comparison
Existing DBA
Modified 4BA
5BA
7BA
Circumference (m)
561.6
561
561.6
561.6
Natural Emittance (pm.rad)
2600
276
155
45.7
Tune Point (Qx / Qy)
27.20 / 13.37
50.76/18.36
53.66/28.87
75.42/52.17
Natural Chromaticity (ξx / ξy)
-80.4 / -35.6
-128/ -94
-130/-50
-348 / -119
Momentum compaction
1.66×10-4
1.02×10-4
1.30×10-4
0.80×10-4
Max Quad. Strength (m-2)
<2 (1.99)
<7
<7
< 10
Max Sext. Strength (m-3)
<35 (20.0)
< 380
< 700
< 326
-
288
192
103
11.3 / 8.3
9.1 / 6.7 / 3.2
9.5/6.5
8.0 / 5.0
Emittance with IBS* (pm.rad)
Length of straight sections# (m)
*Intra-Beam Scattering calculated using ELEGANT for 450mA / 900 bunches / 10% coup / 3.3MV
#Quadrupole to quadrupole separation
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
‘DIAD’ Beamline
Dual Imaging and Diffraction (DIAD) beamline requires high flux in the 4-40keV range
Considering replacing existing cell with a modified 4BA cell
 Introduces an additional straight
section (bending magnet beamline
upgraded to ID beamline)
 Serves as a prototype for low
emittance lattice upgrade
 In line with phased upgrade
 Lots of R&D required (magnet design
challenging, vacuum with small
apertures, engineering integration, etc)
modified
4BA cell
Additional straight
Still work in progress; need to find solution with adequate dynamic aperture and
lifetime before it could be considered. Other options include modified DBA cell or
replacing second bending magnet with a 3T normal conducting super-bend.
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Conclusions
Work at Diamond is continuing on different fronts, partly by increasing the
capacity of the facility by adding new beamlines, but also by upgrading
existing beamlines and improving the performance of the accelerator itself
(e.g. improving MTBF, reducing coupling, increasing beam current, beam
stability, ...)
Other current topics not mentioned so far:
 Low emittance optics for existing lattice
 Girder re-alignment program
 ‘COLDDIAG’ – diagnostic device to study head load on cryogenic surfaces
 Fast polarisation switching during user time (I10)
 Increasing beam current (350mA tests soon, working towards 500mA)
 4th RF cavity
Ian Martin
IOP PAB Group meeting, DL, (April 2013)
Acknowledgements
ARPES (I05)
S. Mhaskar, E. Longhi, B. Singh, R. Fielder, R. Bartolini
Reduced Coupling Studies
D. Hicken, M. Abbott, C. Thomas, R. Bartolini, K. Sawhney
Low Alpha
R. Bartolini, G. Cinque, M. Frogley, P. Karataev, A. Morgun, G. Rehm, W. Shields,
C. Thomas, R. Walker
Diamond Upgrade
R. Bartolini, C. Bailey, M. Cox, N. Hammond, R. Holdsworth, J. Jones, J. Kay, L.
Malysheva, N. Marks, S. Mhaskar, T. Pulampong, R. Walker, ...
Ian Martin
IOP PAB Group meeting, DL, (April 2013)