1. Topup Operation on Diamond
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

2. Topup Operation on Diamond to EPICS Meeting 2008
Decay Mode Operation
Electrons are injected on periodic basis
Determined by Life Time
During injection Shutters are Closed
Part of PSS SR Operate
IDs may be opened, but are put under Control Room control
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

3. Thermal Induced Disturbances
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

4. Topup Operation on Diamond to EPICS Meeting 2008
What is Topup?
Electrons are injected into the Storage on a periodic basis
Injection period determined by stability requirement of stored beam and photon beam
2mins for Diamond
During initial injection Shutters are Closed but once a stored beam is established Topup injection can proceed with Shutters open
Part of PSS in Topup mode
IDs are closed and under beamline control
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

5. Topup Operation on Diamond to EPICS Meeting 2008
Advantages of Topup
Higher average brightness
Higher average current
Constant flux on sample
Improved stability
Constant heat load
Machine components
Beamline optics
Beam current dependence of BPMs
Flexible operation
Lifetime less important
Smaller ID gaps
Lower coupling
Hybrid mode with different life times in MB and SB
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

6. What does it mean for beamlines ?
Safety
Concern that the injection process could fail and the injected electrons would end up in the beamline
Beamline shielding is designed to contain Photons, not electrons or by-products ( Neutrons ) produced by electron interactions
Influence of injection process during topup on photon beam stability.
Imperfections in the injection process disturb the stored beam
Injected beam has to damp down on to the orbit of the stored beam
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

7. Safety Tracking Studies
Carried out tracking studies to establish that each Beam-line is safe for top-up.
This analysis:
Electrons travelling forwards from straight section cannot pass down beam-line
Electrons travelling backwards from beam-line cannot pass through to straight section
Electrons travelling in either direction do not have same trajectory at any intermediate point
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

8. Safety tracking failing Dipole
Dipole bending magnets steer electrons away from beam-line opening
If bending magnets fail, electrons go straight forward (following path of x-rays)
B = 100%
B = 0%
B = 25%
B = 75%
B = 50%
Phase-space borders overlap if B<23%
Stored beam lost if B<~99%
Beam-line I02 safe for this type of error
Plans for Top-Up at Diamond
Ian Martin
ESLS-XV 22nd Nov 2007

9. Safety Interlocks Implemented
To exclude the possibility of transmission of injected electrons into an optics hutch, allowing all possible magnet errors (lattice independence), requires
Stored beam interlock, to exclude single dipole failure upstream of a beamline
Energy interlock, to exclude difference in energy of > 5% between injected and stored beams
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

10. Health Physics Interlock
BL Radiation Monitors are being upgraded to include sensitivity to Neutrons. ( Produced when electrons collide with matter)
Currently interlock is on Dose Rate greater 4uSv/hr
Add a new Interlock on the the Integrated Dose over 4hours at a level of 2uSv.
Gives sensitivity to lower ongoing losses
The 4 hour integrator is integral to monitor
Will be resent by a 4 Reset signal produced every 4 hours by the Timing system.
Resets will be synchronised to start of shift.
HP Interlocks are part of the PSS
On M/C prevent interjection
On BL close Shutter
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

11. Fill Pattern Measurement
Actual fill pattern measured using PicoHarp time-correlated single photon counting system.
Average fill pattern over period between top-up cycles.
Fill pattern is used to determine the buckets to be filled, but number of buckets is determined from overall beam current, measured by DCCT
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

12. Topup Process Establish stored beam (shutters closed)
Close IDs / open shutters
Switch to top-up mode
Test injector (single bunch into BTS stop)
Gun off / switch on BTS dipole
Warm up storage ring pulsed magnets
Identify low-charge bunches from fill pattern
Inject until above stored current threshold
Turn off injector / BTS dipole
2 min delay between injections
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

13. Topup Operation on Diamond to EPICS Meeting 2008
Topup application
Application written in Python
uses the Qt GUI
matplotlib for graphs.
Allows parameters of top-up to be varied.
Provides interface for failure diagnosis.
Allows display of top-up statistics.
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

14. Topup application: Interlocks
Not part of Safety
Intention is:
to prevent top-up from being started in inappropriate circumstances,
to stop top-up before a PSS trip occurs so that the machine falls back to decay mode operation and beam is not lost.
When an error is detected, top-up process stops as cleanly as possible and sets top-up state to “Failed”.
Interlocks includes:
Transfer efficiency B to BTS, Transfer efficiency BTS to SR Stored Beam current, Beam lifetime, Charges in individual SR buckets, shots to correct buck, valves open, and BST correct optics
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

15. Topup Application: Statistics Generated
Statistics are generated to detect any drift in top-up performance.
Generate averages for:
Last 10 cycles
Last hour
Last 6 hours
Last 24 hours
For
Overall, LTB, BTS, and SR
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

16. Topup Operation on Diamond to EPICS Meeting 2008
Topup Test
Total current stable at 128.4mA to 0.1%
Pk-pk ~ 0.2mA
σ ~ 0.06mA
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

17. Imperfections in the Injection Process
160
8.3
22 (nominal)
Septum K1 K3 K4
456.40
(max , min )
233.60
(min , max )
1870mm
850 mm
900 K2
13.7 (nominal)
16 (nominal)
8.5° V
coll H
190
2560
740
8300
At injection the Stored Beam is bumped toward the Septum magnet by a half sine wave pulse lasting ~ 6usec.
Realised use kickers (K1, K2, K3 and K4 )
If perfectly, matched then there is no disturbance to Stored Beam.
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

18. Topup Operation on Diamond to EPICS Meeting 2008
Real Kicker Waveforms
Kicker Pulse are ~6usec and 3900A
There are differences in the PSUs and magnets (asymmetries) and in the coating of the vessels.
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

19. Real Injection Disturbance
Stored beam is disturbed
± 250 um horizontally,
± 150 um vertically
Lasts 10 to 12 msec
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

20. Topup Operation on Diamond to EPICS Meeting 2008
Gating Signals
Top up every 2mins
Top-up requires around 10 shots into the SR
200msec between each shot
Each shot disturbing the stored beam for around 10 to 12 msec. Overall injection period for a top-up cycle would last for around 2 seconds every 2 mins.
At present we are not able to prevent the beam disturbance
Gating signals will be available to stop motion and or the detector, when the beam is disturbed.
Short Gate shot by shot
Long Gate over the whole injection period.
Software and hardware gating signals are provided
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

21. Topup Operation on Diamond to EPICS Meeting 2008
Thanks
C. Bailey, R. Bartolini, P. Bonner, C. Christou, Y. Chernousko, T. Dobbing, A. Gonias, N. Hammond, I. Martin, C. Ide, V. Kempson, E. Longhi, G. Rehm, B. Singh, S. Singleton, R. P. Walker, M Wilson
H. Nishimura, D. Robin, A. Terebilo
And many more…
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

22. Topup Operation on Diamond to EPICS Meeting 2008
Decoded Gate Signals
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

23. Gating Signal Interface
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

24. Possible Beamline EVR Application
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

25. Topup Operation on Diamond to EPICS Meeting 2008
Gating Signal Levels
Ch.0 – Ch.4.
TTL signals on BNC
Ch.5 and Ch.6
TTL levels (coax LEMO)
PECL levels (2-pin LEMO)
LVDS levels (2-pin LEMO).
Ch. 7
Restored RF-CLK PECL ( 2-pin LEMO)
Some channels have fixed names (Short Gate, Long gate, SR CLK and RF CLK)
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

26. Topup Operation on Diamond to EPICS Meeting 2008
References
TDI-CTRL-REQ-009 Beamline Top-up gating requirements summarise requirement for beamlines, I02,I03,I04, I06, I15, I16, I18, I22, I24 and B16.
Now out of date.
TDI-CTRL-TI-SPEC-BL-001 Details the interface for gating signal on beamlines.
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008

27. Topup Operation on Diamond to EPICS Meeting 2008
Topup Super Cycle
Mark Heron
16/10/2008
Topup Operation on Diamond to EPICS Meeting 2008