1. Junji Urakawa ( for collaborators ) March 6 2007 KEK at LNF
Fast Ion Instability Studies at ATF (Preliminary results and proposal for almost perfect experiment)
Junji Urakawa ( for collaborators )
March
KEK
at LNF
2018/11/28
ILCDR07 at INFN-LNF

2. Results obtained in 2004 Problems: meas. of vacuum pressure,
Unknown gas species, extraction kicker heating
2018/11/28
ILCDR07 at INFN-LNF

3. Measured beam profile by XSR monitor in normal vacuum condition
Single bunch/single train
2×1010 bunch/train
Ave: 2×10-7 Pa
X : 49.5±2.3 mm
Y : 8.1±0.7 mm
This profile was appeared
on normal beam operation
2018/11/28
ILCDR07 at INFN-LNF

4. Measured beam profile by XSR monitor in the vacuum condition with north ion pump off
Single bunch/single train
2×1010 bunch/train
Ave: 2×10-6 Pa (Maybe)
X : 46.8±2.9 mm
Y : 8.4±0.8 mm
We have not found
vertical beam size blow-up
in this vacuum condition
2018/11/28
ILCDR07 at INFN-LNF
Change 3train mode

5. Measured beam profile by XSR monitor on 3 train mode
Vacuum : 1×10-5 Pa
profile
profile BG BG
Sample 1
Sample 2
On a 3 train mode at 2×1010 /bunch, sudden large vertical beam blow-up was appeared. On XSR monitor, measured vertical beam size was not fixed on same sizes. We also see a vertical beam oscillation by turn-by-turn monitor.
2018/11/28
ILCDR07 at INFN-LNF

6. Measured beam profile by XSR monitor on 3 train mode (2)
Vacuum : 2×10-6 Pa
profile BG
Sample 1
Sample 2
On a 3 train mode at 2×109 /bunch (1/10 reduction than before), vertical beam blow up was also appeared. But this amplitude was reduced on XSR monitor. The measured beam sizes were 32.5±0.9 mm horizontally and 24.7±4.7 mm vertically. After changing single train, we did not find this vertical beam blow-up.
2018/11/28
ILCDR07 at INFN-LNF

7. Bunch Length Measurement (Synchronized Streak Camera)
2018/11/28
ILCDR07 at INFN-LNF

8. Laser wire beam size monitor in DR
14.7µm laser wire for X scan
5.7µm for Y scan
(whole scan: 15min for X,
6min for Y)
300mW 532nm Solid-state Laser
fed into optical cavity
Expert had a cold during study. Measurements was cancelled.
2018/11/28
ILCDR07 at INFN-LNF

9. Summary of Feb. 23 Study
We found the vertical beam blow-up at 3 train mode above 2×10-6 Pa between 2×109 and 2×1010 /bunch.
We did not find the vertical beam blow-up at single bunch/ single train mode below 2×10-6 Pa.
2018/11/28
ILCDR07 at INFN-LNF

10. Study in Feb. 28 3 bunches/train injection with 2.8ns bunch spacing
Problem : beam loading compensation system could not work. We repair it soon.
Total intensity : 2.43x1010 electrons/train
No beam blow-up (4.5x10-7 Pa, ~8.76mm)
3 bunches/train, 3train ~19mA, IP off
beam blow-up, not clear (4.8x10-6 Pa, ~11.5mm)
2018/11/28
ILCDR07 at INFN-LNF

11. Summary of Feb. 28 Study 3 bunches/train x 3 train operation, 18mA
Storage mode, 6.6x10-5 Pa,
beam blow-up
IP01 On (3.7x10-6 Pa), IP02 On (3.7x10-6 Pa),
IP03 On (2.4x10-6 Pa), beam size gradually reduced.
No blow-up
IP04 On, IP05 On, IP06 On, IP10 On,
IP11 On (1.6~1.5x10-6 Pa)
2018/11/28
ILCDR07 at INFN-LNF

12. Gas Inlet Chamber : N2 etc.
Energy spread monitor
Laser wire monitor system
X-SR Monitor,
Bunch length monitor
2018/11/28
ILCDR07 at INFN-LNF

13. Good pressure bump From vacuum gauge, we evaluate the Beam sees 24mm
pressure distribution
precisely.
Beam sees 24mm
diameter beam
pipe with pumping
slots.
2018/11/28
ILCDR07 at INFN-LNF

14. Necessary preparation and overhaul
Multi-bunch energy compensation system in ATF Linac (Repair it soon.)
Check laser wire
20GHz signal sampling system in DR
Tuning for high quality beam injection
(beam stability, high current injection more than 70mA/train)
2018/11/28
ILCDR07 at INFN-LNF

15. Who's Planning What? (An incomplete list…)
ANL CI
Cornell
DESY
FNAL
IHEP
KEK
LBNL
LNF
SLAC
kickers 
e-cloud
impedance X
lattice design
low-y
ions
vacuum
acceptance
RF system
RF controls
align/support
mech.integration
instrumentation
feedback system
wiggler
main magnets
KNU, PAL X
X X
2018/11/28
ILCDR07 at INFN-LNF

16. ATF R&D Items
Demonstration of Fast Kicker Performance with multi-bunch flat beam (No beam extraction, Measurement of Coherent Oscillation precisely), using strip-lines and FID pulse power supplies. ( ongoing )
Design and Installation on extraction fast kicker for ATF2, Specification : bunch-by-bunch extraction for generation of 30 bunches/train or 60 bunches/train. (late 2008 or 2009)
Almost perfect experiment for fast ion instability. (2007)
Impedance measurement of ATF DR (almost perfect bunch length measurement). (2008)
Micro-wave instability study (CSR measurement). (2008)
1pm vertical emittance generation study if possible. (2009)
Other miscellaneous R&D (Instrumentation Development).
2018/11/28
ILCDR07 at INFN-LNF

17. Goals of the experiment (according to Two proposals (L. Wang, T
Goals of the experiment (according to Two proposals (L. Wang, T. Raubenhimer and G. Xia, E. Elsen)
Distinguish the two ion effects: beam size blow-up and dipole instability.
Quantify the beam instability growth time and tune shift. The growth rate is related to the ion density (vacuum pressure, average beam line density, emittance, betatron function and so on).
Quantify the bunch train gap effect
Provide detailed data to benchmark simulations with experiment.
2018/11/28
ILCDR07 at INFN-LNF

18. Detailed Experiment plan
Measurement of vacuum pressure and the main components of gas species.
Effects of pressure and bunch current:
With different pressure conditions (2.0x10-5 Pa
in pressure bump) by injecting nitrogen gas);
With different beam: 1 train, N of bunch =2~20,
5x109~2X1010/bunch
Gap effect
repeat B with 2 and 3 bunch trains,
repeat B with different length of gaps.
repeat above with a different emittance (emittance ratio :changed by skew quads from 0.5% to 10%.)
2018/11/28
ILCDR07 at INFN-LNF

19. Announcement for efficient collaboration
ATF Web is involving and making international data communication page.
Welcome to the ATF International Collaboration
Announcements
4th Joint meeting of TB and SGCs on May at Daresbury
Call for new R&D proposals at ATF
New system for KEK dormitory reservation KEK users office prepared the online system for user support. It will be activated on March 1st for the dormitory reservations from April 1st. Please read announcements by Users Office. (English) (Japanese)
What's new?
1 March XTF has been cleared for ATF2 construction
Next pictures show the ATF2 area before moving(left) and after moving(center and right) the X-band test station. Floor refurbishment will be start on June after moving Crab-cavity items. Yellow line shows the boundary of floor refurbishment(left side).
2018/11/28
ILCDR07 at INFN-LNF

20. http://atf.kek.jp/collab/ Studies about the Fast Ion Instability
This is a starting point for data sharing within the collaboration of the fast-ion R&D program. It is just started. Therefore we have no tools converting the internal data format into your environment at present. Raw data are distributed in some computers at ATF because of the developments of monitors are done by several groups. Each beam-monitor system has their own format on the different operating system, 8, 16, 32 or 64 bits. It is very difficult to gather them in a server at present. Your help or work to establish the data sharing tools for near future is necessary. Anyway, we will keep to upload the results for your works.
Nobuhiro Terunuma, March 1st, 2007.
Data and Summary
Logging into the ATF web system is required. If you have no account on the ATF web system, please visit the user registration page .
2007/Feb/28
2007/Feb/23
2018/11/28
ILCDR07 at INFN-LNF