1. Diamond Light Source Status and Future Challanges
R. Bartolini
Diamond Light Source Ltd
and
John Adams Institute
University of Oxford
DL-RAL Joint Accelerator Workshop
20 January 2009

2. DL-RAL Joint Accelerator Workshop
Summary
1) Introduction to Diamond
2) Status of the 3 GeV Storage Ring
Orbit correction; Optics control; IDs; Orbit stability;
3) Latest developments and future challenges
Top-Up operation;
Further ID installation; Customised optics;
Ultra short radiation pulse generation;
DL-RAL Joint Accelerator Workshop
20 January 2009

3. peripheral labs. and offices
Diamond Layout
100 MeV Linac
3 GeV Booster
C = m
3 GeV Storage Ring
C = m
Experimental Hall and Beamlines
technical plant
peripheral labs. and offices
office building
235 m
future long beamlines
235 m

4. Milestones and key facts
First LINAC beam (100 MeV)
First turn in booster
First turn in Storage ring
Beamline commissioning start
First users
300 mA
January 2009: 13 IDs operational
2007: h operation (uptime for users 92.4%)
2008: h operation (uptime for users 94.9%)
2009: h operation
31st August 2005
21st December 2005
3rd May 2006
23rd October 2006
29th January 2007
15th September 2007
DL-RAL Joint Accelerator Workshop
20 January 2009

5. Diamond storage ring main parameters non-zero dispersion lattice
Energy 3 GeV
Circumference m
No. cells 24
Symmetry 6
Straight sections 6 x 8m, 18 x 5m
Insertion devices 4 x 8m, 18 x 5m
Beam current 300 mA (500 mA)
Emittance (h, v) 2.7, 0.03 nm rad
Lifetime > 10 h
Min. ID gap 7 mm (5 mm)
Beam size (h, v) 123, 6.4 mm
Beam divergence (h, v) 24, 4.2 mrad
(at centre of 5 m ID)
48 Dipoles; 240 Quadrupoles;
168 Sextupoles (+ H / V orbit correctors + Skew Quadrupoles );
3 SC RF cavities; 168 BPMs

6. DL-RAL Joint Accelerator Workshop
Diamond Storage Ring
DL-RAL Joint Accelerator Workshop
20 January 2009

7. Storage Ring Closed Orbit < 1m (first achieved 22th October 2006)
The beam orbit is corrected to the BPMs zeros by means of a set of 168 dipole corrector magnets:
the BPMs can achieve sub-m precision; the orbit rms is corrected to below 1 m rms:

8. (see ICFA newsletter, Dec’07)
Correction of linear optics with LOCO (Linear Optics from Closed Orbit)
LOCO: fits quadrupoles to reproduce the theoretical closed orbit response matrix
circles = model
crosses = measured
Modified version of LOCO with constraints on gradient variations
(see ICFA newsletter, Dec’07)
 - beating reduced to 0.4% rms
Quadrupole variation reduced to 2%
Results compatible with mag. meas.

9. Emittance and energy spread measured using two X-ray pinholes cameras
Measured emittance very close to the theoretical values confirms the optics
Emittance
2.78 (2.75) nm
Energy spread
1.1e-3 (1.0e-3)
Emittance coupling
0.5%
Emittance coupling is now routinely corrected to 0.1% with LOCO
Closest tune approach 0, rms Dy 1 mm

10. 13 Insertion Devices operational
Beamline ID
Type
I02
U23
In-vacuum
I03
U21
I04
I06
HU64
APPLE-II
I15
SCW
3.5 T Superconducting Multipole Wiggler
I16
U27
I18
I22
U25
I07
I11
U22
I19
I24
I04.1
30.8 mm
Short ex-vacuum
7 IDS in Phase I
and
first ID of Phase II
were installed and commissioned in early 2007
10 in-vacuum undulators
1 variable polarization APPLE-II device
1 3.5T superconducting wiggler
1 short ex-vacuum

11. Orbit stability requirements at Diamond
Beam stability should be better than 10% of the beam size and divergence
but IR beamlines will have tighter requirements
for 3rd generation light sources this implies sub-m stability
For Diamond nominal optics (at the centre of the short straight sections)
Strategies and studies to achieve sub-m stability
identification of sources of orbit movement
passive damping measures
orbit feedback systems

12. Ground vibrations to beam vibrations
Amplification factor girders to beam: H 31 (theory 35); V 12 (theory 8);
1-100 Hz
Horizontal
Vertical
Long Straight
Standard Straight
Position (μm)
Target
17.8
12.3
1.26
0.64
Measured
3.95 (2.2%)
2.53 (2.1%)
0.70 (5.5%)
0.37 (5.8%)
Angle (μrad)
1.65
2.42
0.22
0.42
measured
0.38 (2.3%)
0.53 (2.2%)
0.14 (6.3%)
0.26 (6.2%)

13. Significant reduction of the rms beam motion up to 100 Hz;
Global fast orbit feedback at Diamond
1-100 Hz
Standard Straight H
Standard Straight V
Position (μm)
Target
12.3
0.64
No FOFB
2.53 (2.1%)
0.37 (5.8%)
FOFB On
0.86 (0.7%)
0.15 (2.3%)
Angle (μrad)
2.42
0.42
0.53 (2.2%)
0.26 (6.2%)
0.16 (0.7%)
0.09 (2.1%)
Significant reduction of the rms beam motion up to 100 Hz;
Higher frequencies performance limited mainly by the correctors power supply bandwidth

14. Summary of Current Machine Status
Target Achieved
Energy 3 GeV 3 GeV
Beam current 300 mA 300 mA Machine Development
250 mA User Mode
Emittance
- horizontal 2.7 nm rad 2.7 nm rad
- vertical 27 pm rad 4-50 pm rad ~ 27 pm in User Mode
Lifetime at 300 mA > 10 h ~ 18 h
Min. ID gap 7 mm 5-7 mm User Mode, dep. on ID
Stability < 10% 2.3% (H), 6.3% (V) No feedback
of beam size 0.7% (H), 2.3% (V) Feedback, Hz
& divergence
DL-RAL Joint Accelerator Workshop
20 January 2009

15. Top-Up motivation
Top-Up operation consists in the continuous (very frequent) injection to keep the stored current constant to prevent the natural beam current decay
Higher average brightness
Higher average current
Constant flux on sample
Improved stability
Constant heat load
Beam current dependence of BPMs
Flexible operation
Lifetime less important
Smaller ID gaps
Lower coupling
BPMs block stability
without Top-Up  10 m
with Top-Up < 1 m
Crucial for long term sub- m stability

16. DL-RAL Joint Accelerator Workshop
User-Mode Operations
“Standard” operation: 250 mA maximum, 2 injections/day
DL-RAL Joint Accelerator Workshop
20 January 2009

17. DL-RAL Joint Accelerator Workshop
Top-Up operation
First operation with external users, 3 days, Oct th
No top-up failures, no beam trips due specifically to top-up
Now Top-Up is the regular user operation mode
DL-RAL Joint Accelerator Workshop
20 January 2009

18. Future Insertion Devices
Beamline
date
Type
I12
Mar 09
4.2 T Superconducting Multipole Wiggler; contract with BINP;
Beamline extending outside diamond buliding
I20
Jun 09
2 x hybrid wigglers 2T, W83, construction in-house;
I07
End 09
Cryogenic Permanent Magnet Undulator (U17.7) contract with Danfysik. Will substitute the in-vacuum U23 device installed as a temporary measure.
I10
2010
Two APPLE II devices with 10 Hz polarization switching using 5-kicker scheme; engineering implications under study
 2 girder changes
I13
Two In-vacuum undulators with “double mini-beta” optics proposed;
beam dynamics and engineering implications under study.
1 or 2 girder changes
I09
2011
Helical undulator + in-vac. CPMU, with “double mini-beta” optics proposed; beam dynamics implications under study.
 1 or 2 girder changes

19. Customised optics in long straight sections
A long straight sections is divided into two by a triplet of quadrupoles
to achieve double mini beta in V and a virtual focus in H for coherence applications
Pos. ‘A’

20. DL-RAL Joint Accelerator Workshop
I13 beamline
DL-RAL Joint Accelerator Workshop
20 January 2009

21. Ultra-short radiation pulses in a storage ring
There are three main approaches to generate short radiation pulses in storage rings
e– bunch
1) shorten the e- bunch
2) chirp the e-bunch + slit or optical compression
3) Laser induced local energy-density modulation
Low – alpha optics
Higher Harmonic Cavities
RF voltage modulation
Crab Cavities
Synchro-betatron kicks
Femto–slicing

22. z depends on the magnetic lattice (quadrupole magnets) via 
Low alpha optics
If high current effects are negligible the bunch length is
 = 1.710–4; V = 3.3 MV;  = 9.6 10–4
z = 2.8 mm (9.4 ps)
z depends on the magnetic lattice (quadrupole magnets) via 
We can modify the electron optics to reduce 
 (low_alpha_optics)  10–6
z  0.3 mm (1 ps)

23. Machine tests with 1 ps lattice
fs = 340Hz => α1 = 3.4×10-6, σL = 1.5ps
fs = 260Hz => α1 = 1.7×10-6, σL = 0.98ps
fs=340Hz
fs=260Hz
ε = 34 nm.rad; κ = 0.03%
Qx = ; Qy =

24. DL-RAL Joint Accelerator Workshop
Future Work
Continue optics optimisation
maintain nominal optics, lifetime characterisation, injection efficiency;
characterisation of the non-linear optics (pinger magnet installed by end of 2007)
Continue ID commissioning (Phase II and Phase III ID installation till 2014)
optics compensation vs gap, DA effect, lifetime vs gap, frequency map vs gap
ID request operation at 5 mm gap
High current operation (300 mA) and TMBF
impedance database; characterization of the instabilities (multi-bunch, single bunch)
Maintain/Improve Top-up, FOFB performance
Low alpha optics for users
Thanks to R. Fielder, E. Longhi, I. Martin, B. Singh, J. Rowland and staff from Diagnostics, Controls, Operations, IDs, RF, …
DL-RAL Joint Accelerator Workshop
20 January 2009