SPEAR3 Commissioning News

February 2004

SPEAR3 Commissioning Continues Smoothly

SPEAR3 commissioning continues to proceed remarkably smoothly, thanks to the efforts of the SSRL staff and visitors from laboratories world-wide. 100 mA was first stored on January 22. Since then the lifetime has been steadily increasing with vacuum scrubbing, reaching 13 hours and climbing at 100 mA prior to the week-long shutdown starting February 23.

Measurements of the electron orbit show that it is very stable. The absolute orbit can be placed in the storage ring magnet centers to within a couple tens of microns. The fill-to-fill reproducibility of the orbit at the beam positions monitors (BPMs) is about 1 micron. Without feedback, the orbit drifts only a few tens of microns over the course of many hours. With orbit feedba ck, this is reduced to about 1 micron, as measured by the BPMs. The rms orbit motion in frequencies between 1 and 100 Hz is about 2 microns, which compares well to other 3rd generation light sources. Later this year, we will be implementing a fast orbit feedback to further damp these frequencies. We see some small beam oscillations at the vertical betatron frequency (300 kHz). These oscillations appear to be associated with ions, and ar e disappearing as the vacuum improves.

The linear optics functions have been corrected to within a couple percent of design. Measurements of the nonlinear optics distortions are also quite close to predictions, which has resulted in good injection efficiency and lifetime (for this stage of vacuum conditioning).

The remaining days of storage ring commissioning will be dedicated to investigating how much we can push the optics to allow smaller gaps in future IDs, commissioning the LIONs (a beam containment system), and preparing to deliver beam to beamlines.

The speed and relative ease of commissioning is a testimony to the excellent design, engineering, and construction work done by the SSRL and SLAC staff.

January 22, 2004

SPEAR3 Achieves 100 mA Stored Current Milestone

Stored current in SPEAR3 reached 100 mA at about 10 pm Th ursday Jan 22. The newly repaired Stored Current Interlock stopped injection at 105 mA as specified. The lifetime at 100 mA was ~4.5 hr - not bad for now. We expect it to improve by a factor of 10 or more when the ring is fully scrubbed and tuned up. Thanks to the EE, EDM, Accel Phys and Operations staff who perservered in solving the Current Interlock problems and enabling us to reach the 100 mA goal.


January 20, 2004

SPEAR3 Achieves 100 mA Stored Current Milestone

Over the MLK holiday weekend the commissioning team was able to verify the integrity of the Orbit Interlock for protecting narrow-gap insertion device chambers from mis-steering of upstre am dipole radiation. Consequently, we proceeded with the program to fill to 100 mA with IDs open, but were thwarted at ~52 mA by a mis-function of the Stored Current Interlock. No problems were encountered with vacuum chamber pressure, heating, or beam instability.
The Current Interlock problem is expected to be resolved during the Tuesday maintenance period, and the Orbit Interlock also will be modified to permit ID operation at 100 mA. We hope to be operating at 100 mA soon.
A dedication celebration is planned for Thursday, January 29th to recognize the people who made the project successful as well as the state-of-the-art science that SPEAR enables. More about this celebration will be posted here as available. Please join in celebrating this milestone on January 29th!

Januar y 1, 2004

Excellent Commissioning Progress over the Holiday Break

The commissioning of SPEAR 3 has progressed extremely well during the December holiday break. The following message was sent by James Safranek, head of the commissioning team, on New Year's Day, 2004:

"SPEAR3 commissioning has been going remarkably well. The first beam was stored on December 15th. Since then, we have been working to commission the diagnostics, correct the orbit, and correct and control the linear optics. To date we have limited the fills to 20 mA to avoid damaging the vacuum chamber. We expect to push to higher currents sometime within the next week.

"The speed and lack of problems with commissioning to date is a testimony to the high quality of the accelerator. High praise goes to those who designed and built SPEAR3!"

December 15, 2003

First Accumulated Beam in SPEAR3!

The first accumulated beam in SPEAR 3 occurred at 17:13:45 on Monday Dec. 15, 2003. It was stopped at ~1 mA to allow conditioning of the vacuum system. The staff is now pursuing measurements of beam parameters. Congratulations to all those who have contributed to the SPEAR 3 project!

As has been the case throughout the SPEAR3 project, extraordinary teamwork has been a key component. The SPEAR3 upgrade was made possible by the joint support and funding by the U.S. Department of Energy and the National Institutes of Health. Construction and installation work was performed jointly by contractors and staff from SSRL along with numerous other divisions at SLAC. The major milestone of first electrons circulating around SPEAR was made possible by the accelerator staff here with assistance from the A dvanced Light Source (ALS). We particularly want to acknowledge David Robin and Christoph Steier from the ALS for their late-night help in obtaining the first turns. Congratulations and thank you to everyone who has made and continues to make the SPEAR3 project both possible and successful!

December 12, 2003

First Electrons Circulate in SPEAR3!

Major milestones were observed this week as SPEAR operators reported the first beam signals at SPEAR3 on December 10th - right on schedule! The following day around 2 am, the first injection into SPEAR3 occurred when a single 3 GeV bunch was inj ected into SPEAR3 and made a complete turn around the ring. By the afternoon of December 11th, 10-15 turns were observed, which is as much as was expected without the RF system. On December 12th, operators plan to turn on the RF system which will enable the possibility of actually storing beam. These activities demonstrate that most of the major systems are working as planned and provide encouragement that starting and commissioning thi s third generation light source at SSRL will continue to proceed smoothly.



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last updated: MAR 09, 2004 a.mueller