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Status of the TLS Accelerator Facility Status

Introduction are amazingly equipped inside the compact storage
As the first synchrotron light source of NSRRC to ring of TLS as Fig. 1 shows. Table 2 lists the main
serve public users beyond two decades, Taiwan Light parameters of these insertion devices.
ACTIVITY REPORT 2016
Source (TLS) is capable of storing an electron beam
up to 360 mA at energy 1.5 GeV. Being a third-gen- Table 1: Beam parameters of TLS storage ring
eration light source, the electron storage ring of TLS Energy (GeV) 1.5
has circumference 120 m of six-fold symmetry with Number of buckets 200
6-m straight sections for injection, radio frequency Current (mA) 360
(RF) cavity and long insertion devices, respectively. A Bunch length (ps) 31
significant maintenance effort is required to enable Horizontal emittance (nm rad) 22
this mature accelerator to function regularly at high Vertical emittance (pm rad) 88
availability and excellent stability; as a result the TLS Tunes (ν x/ν y) 7.302/4.17
accelerator still features top-up injection, supercon- Vertical (rms) orbit stability (μm) 1.0
ductive RF-module operation, and various traditional Coupling (%) 0.4
and superconducting insertion devices.
RF voltage (MV) 1.6
Lifetime (hour) 6
TLS machine parameters
Table 1 lists the major beam parameters of the TLS
storage ring. This accelerator has a compact circum- Statistics of TLS machine operation
ference and only four straight sections available for From the beginning of the 200-mA top-up injection
long insertion devices; short superconducting (SC) operation in 2005 October, TLS gradually increased
magnets are installed at small gaps to accommodate the stored beam current to 360 mA in 2010 and
the demands to provide more beamlines with high stayed there in the following years because of the
brightness. An SC wavelength shifter is located be- limitation of available RF power after installation of
tween injection kickers K3 and K4 at the injection the SRF module. We always aimed to improve the
section; one SC wiggler is situated downstream of the performance of the facility as indicated by availabil-
superconducting radio frequency (SRF) module; three ity, mean time between failures (MTBF) and beam
in-achromat SC wigglers (IASW) squeeze between stability index. Availability is defined as the ratio of
the bending magnets at separate bending sections. delivered user time to the scheduled user time; MTBF
Accompanying the traditional insertion devices as the ratio of scheduled user time to number of
(EPU56, U50, U90, and W200), nine insertion devices faults; the beam stability index is the time ratio of the
photon intensity variation shot to shot of the diag-
nostic beamline better than 0.1%. Together with the
scheduled user time and the operating mode, these
performance indicators for TLS operation from 2003
to 2016 are listed in Table 3. Figure 2 shows the
related performance indicators from 2006, while the
accelerator operation was steady.

The operational perfor-
mance of TLS in 2016
is mostly better than
in 2015; on the basis
of scheduled user time
5526 h, the delivered
user beam time was
5427 h, to achieve avail-
ability 98.2%; the MTBF
and the beam stability
Fig. 1: Layout of TLS accelerator. index increased to 100.5