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Table 4: Monthly beam stability index of TLS Downtime and failure
analysis
Month < 0.1% < 0.2% Month < 0.1% < 0.2% Facility Status
In 2016, in total there were 55
January 95.3% 99.9% July 97.0% 99.9% beam trips with an average recov-

February 98.0% 99.9% August 95.9% 99.8% ery time 1.8 h for each trip event.
As Table 5 illustrates, 11 beam
March 99.0% 99.9% September N/A N/A
trips were attributed to others,
April 99.5% 99.9% October 98.1% 99.8% including partial beam loss, sag of
ACTIVITY REPORT 2016
May 97.1% 100.0% November 97.5% 99.8% electric power and earthquakes;
5 faults to power supplies of the
June 97.0% 99.9% December 97.7% 99.8%
magnets, nine faults to SC mag-
nets and six failures of the injec-
tion system, including incorrect fir-
ing of kickers. A partial beam loss
during injection in top-up opera-
tion was still a major problem of
TLS, as before, as the RF protection
loop detected an abnormal power
change and then activated the
interlock to trip the RF system so
as consequently to kill the stored
beam. Many tiny fluctuations and
rapid abnormal behaviors of in-
jection-related units could cause a
partial beam loss; a diagnostic sys-
tem with a rapid transient record-
er was hence built to identify the
occasional event. Figure 4 shows
a partial beam-loss event with an
abnormal timing trigger wave-
Fig. 3: Quarterly beam performance of TLS for user time in 2015 and 2016. form from a pulsed power supply
of the kicker. The main board of
the kicker controller was then
replaced as an attempt to solve
Table 5: Summary of major trip events this trigger problem. The rapid
Subsystem Event Beam trips diagnostic system assisted greatly
Others Partial beam loss without a clear reason 6 to decrease the partial beam-loss
Others Sag of electric power 2 events, but unclear consequenc-
Others Earthquake 3 es still occurred. Further effort is
Power supply Power supply of sextuple magnet failure 3 required to improve this system
Power supply Power supply of corrector magnet failure 8 and to examine the consequences
Power supply Power supply of quadrupole magnet failure 3 and reasons.
Transport line power supply of dipole magnet fail,
Power supply 1 Table 5 shows clearly also that
lower than user beam definition.
Magnet SC magnet fail 9 some components of the subsys-
Injector Incorrect firing of kickers 5 tems, such as power supply and
Linac Aged klystron modulator power supply relay 1 injection system, are approaching
their lifetimes. This occurrence
affects all subsystems of TLS after
construction nearly three decades
RF system: ago. As some components are
• Beam processing on the SRF module was applied by adjusting various even unavailable any more, prepa-
tuning angles with large beam currents after a scheduled shutdown pe- ration work such as to modify the
riod, to increase the reliability of the RF system as a vacuum burst event interfaces in advance at scheduled
in a SRF module was eliminated. shut-down periods is critical to
upgrade the old components with
new modules before failure.