ESRF
The facility now includes 26 operational beamlines, which will increase to
39 by the end of Phase II (end '98). The machine reliability is very good, with
95 % average up-time in '96 and mean time between failures of 41 hours. Reliability
has been increased significantly by the non-interruptable power supply, which
avoided more than 220 electrical fluctuations. Only occasional direct hits by
lightening now cause machine stoppage. Operation of a second klystron has also
reduced downtime due to the r.f. system. Seven different filling modes are currently
used. The lifetime increase in 2/3 filling compared to 1/3 filling clearly shows
that the Touschek effect also plays a role with high energy machines. Machine
developments in '96 have included new lattice functions with low vertical beta
in all straight sections, reduction of the coupling to 1 %, development of 8
mm internal/10 mm external copper-plated vacuum vessels, and the test of a Spring-8
in-vacuum undulator. The first new filters have also been installed on the beam
lines to allow the use of three undulator sections with 200 mA stored current.
The goals for 1997 are 5400 hours for user operation (with about 18% of the
total time dedicated to start-up and machine studies), commissioning of a third
r.f. plant and installation of the new low gap ID chambers. Studies will also
be made for a further reduction in the emittance (3 nmrad) and coupling
(0.3 %).
MAX II
The commissioning phase for MAX II has now ended and the operational phase
is beginning. Both the design energy and current have been reached. MAX I is
used as the injector providing 30 mA/shot, once per minute, allowing a re-filling
time of 10-20 minutes. The capture efficiency between the two machines is about
40 %. MAX II has non-zero dispersion in the straights. The sextupole fields
for chromaticity compensation are generated in the quadrupoles, with backleg
coils for adjustment. No major problems have been observed due to the integrated
sextupole fields; two different optics have been tried, although not greatly
different in sextupole strength. SIP's in the bending magnet chambers are used
for pumping and titanium sublimation pumps are used once per week. The lifetime
is lower than foreseen (0.7 Ah, instead of 2 Ah) and is probably due to the
lower coupling than expected (1 rather than 10%). The energy acceptance is 1.5%.
There is little demand for short bunch lengths and a greater demand for low
emittance and so rather than acting on the coupling to increase the lifetime
a Landau cavity, working at the third harmonic 1.5 GHz, will be installed to
increase the bunch length. At the same time it will combat multi-bunch instabilities
by providing synchrotron tune spread. No bunch length measurements have yet
been performed. The first phase of beamline construction foresees the installation
of four beamlines for insertion devices and two from bending magnets.
DORIS III
The last major rebuilding of the facility has been to remove the vertical
bending magnets in order to eliminate the vertical dispersion, as well as to
save money on electrical power. A new ID vacuum chamber has been installed with
11 mm internal and 15 mm external dimension, consisting of copper halves soldered
together with distributed NEG pumping. Nine photon beam position control loops
are in operation using information from photon beam monitors. Closed orbit movements
have been traced to the asymmetric heating of the dipole chambers at the ID
outlet, causing movement of the adjacent quadrupole chamber, and also of the
quadrupoles themselves. Six new chambers will therefore be installed in mid
'97 with additional cooling on the inner side of the chamber; at the same time
the fixing of the quadrupole vessels to the magnets will be removed. Overheating
of the vertical multibunch feedback limits the current that can be obtained
in the 5-bunch mode; to solve the problem a new design with water cooled ferrite
will be installed during the next summer shutdown.
DELTA
First stored beam at 1 GeV was achieved in DELTA on the 16th August, followed
by accumulation of 10 mA (limited by vacuum effects) in October. Radiation from
the FELICITA 1 undulator has been observed and also transported out of the shielding
wall. The ring is presently shutdown for bake-out and NEG activation. The linac
is operating at 70 MeV due to an r.f. power limitation. The booster has recently
been improved to increase the rep. rate (10 cycles/minute) and reduce beam losses.
Stray fields from the booster which affect the storage ring have been noted.
The plans for '97 are to commission the 4-bunch FEL mode as well as the 1.5
GeV SR user mode, to install the optical cavity and obtain lasing.
Kurchatov Synchrotron Radiation Source
The six-fold symmetric storage ring, SIBERIA II, achieved full energy (2.5
GeV) and 10 mA in July '96. By the end of the year 100 mA should be achieved,
as well as the first experiments performed on the first 3 VUV beamlines. The
chamber is made of aluminium with some parts in stainless steel. An 180 MHz
r.f. system has been adopted. SIBERIA I is used as injector (450 MeV) with a
cycling time of 30 seconds. A large number of beamlines are under construction.
A collaboration for LIGA technology is in progress with the university of Mainz.
In 1997 it is hoped to commence regular X-ray experiments with 300 mA beam current.
ELETTRA
ELETTRA is currently operating for a total of about 6100 h/yr. with 5000 h
for users, and with an average up-time of about 92 %. The major source of down-time
is due to storms, predominantly in the summer months. Injection is performed
once per day at 1 GeV, followed by ramping to 2 GeV, with an initial current
of 250 mA. The total time for a re-injection is around 20 minutes. There are
no requests at present to operate in single bunch mode. Five IDs are operational
as well as one bending magnet beamline. Higher order modes in the r.f. cavities
are cured by a combination of cavity temperature adjustment and HOM frequency
shifters. Some residual longitudinal excitation is accepted in order to increase
the beam lifetime. Developments in progress include substitution of BPM gaskets
to permit higher beam currents, installation of adjustable HOM frequency shifters
in all 4 cavities, development of a transverse coupled bunch feedback system
and a global orbit feedback system, and increased automation. An electromagnetic
elliptical wiggler has been designed and will be installed in 1997. Lower gap
ID vessels are also under study. prepared by C.J. Bocchetta and R.P.
Walker