New Milestone for SPEAR3
By Francoise Chanut
SPEAR3, SSRL’s recently upgraded
synchrotron radiation source at SLAC, reached 500 milliamps (mA) for the
first time on June 20, and again on June 21.
“We were able to go to the design current without any
problem related to instability in the electron beam,” Piero Pianetta (SSRL)
shows the duration of the high-current run.
(Image courtesy of
The milestone was achieved as part
of a series of tests designed to bring SPEAR3 to its full design
performance. SPEAR3 has been running at 100 mA for the past year and a
half but will ultimately operate at 500 mA routinely, generating
brighter X-ray beams that will make new experiments possible. “It was a
major step, the fruition of almost nine years of hard work and a lot of
meetings!” Bob Hettel (SSRL) said. The SPEAR3 upgrade was first
discussed in 1996 and made possible by funding from DOE and NIH, he
Hettel and members of a
multi-disciplinary team tested SPEAR3 on June 20 and 21. They gradually
increased the electron beam intensity from 100 to 500 mA over the course
of four hours, carefully checking for potential damage to the equipment
at every step. They did not encounter any problems, Hettel said. The
electron beam did show some instability at first, but the problem was
easily corrected the second night with the help of engineers from the
CPE and Klystron/Microwave groups, he said.
“This achievement is a demonstration of the tremendous
energy and teamwork of the SSRL SPEAR3 accelerator group working closely
with other key staff at SLAC,” said Photon Science Director Keith
Hodgson. “Achieving maximum design performance so smoothly reflects the
quality of the accelerator and control system and reinforces the value
of the significant investment by DOE and NIH in building the new
A test run of SPEAR3
at 200 mA a year ago had gone similarly smoothly, but further
preparation was needed to meet the requirements of a DOE-mandated
Accelerator Readiness Review before the 500 mA test.
The next big step now is to complete the upgrade of the
synchrotron radiation beam lines. The first beam lines ready for 500-mA
operation will be available to users in 2006, Hettel said.
“Operating at maximum performance levels, SPEAR3 will
provide SSRL’s users with capabilities equivalent to the best in its
class in the world, and enable scientific discovery in areas like study
of nano-structured materials and microcrystal diffraction which will
take full advantage of the high brightness of SPEAR3,” Hodgson said.