Vacuum Control System for SuperKEKB

Transcription

1 Vacuum Control System for SuperKEKB S.Terui, H. Hisamatsu, T. Ishibashi, T. T. Nakamura J. Odagiri, Y. Suetsugu (KEK), N. Yoshifuji (EJT)

2 Contents Overview of SuperKEKB vacuum control Upgrade of configuration Interlock system High speed data acquisition of CCGs pressure values Conclusions

3 Overview of SuperKEKB Vacuum Control System Components AI AO DI DO Vacuum Switch 67 Gate Valve Stopper CCG Ion Pump NEG Power Supply Flow Meter Temperature Sensor SuperKEKB is a two ring electronpositron collider with asymmetric energies

4 Needs for Upgrading Control System Vacuum Control System of KEKB had been operated successfully based on: VME based IOC CAMAC (scanning ADC and DI/DO) SuperKEKB is expected to be in operation for decades from 2014 Availability of CAMAC modules will be a serious issue We decided to apply Embedded EPICS concept to upgrading the system with up to date controllers and data loggers

5 Upgrade of Configuration We chose F3RP61 (made by YOKOGAWA) as IOC Can work with ordinary PLC s CPU side by side on the same PLC bus Can run LINUX We chose CompactRIO (crio, made by NI) Can run Channel Access (EPICS protocol) Server on crio High analogue I/O channel density in compact chassis (32ch/module) Can execute high speed data acquisition on built in FPGA OPI IOC (VME) Ladder Program makes the final decision in ON/OFF control Old System Configuration CPU Channel Access PLC CAMAC DO GPIB DO DI DI AI CPU OPI PLC New System Configuration DO DI Channel Access Channel Access crio IOC (F3RP61) The new system is simpler than the old system. DI AI

6 IOC and Data Logger Upgrade IOC (VME ) IOC (F3RP61) CAMAC (very heavy) crio (very light) Before After

7 Concept of Interlock We built the normally closed interlock logic with digital input or output modules and the sequence CPU module of the PLC unit to ensure the safety in the operation of the vacuum start up and the steady state after it. The source components of the input signal are temperature sensors, flow meters, gate valves and beam stoppers, vacuum switch, CCGs.

8 Interlock Logic (Introduction) We put a CCG and ion pump every 10 m in SuperKEKB main ring. Gate valves divide the vacuum region to ensure serviceability of the vacuum components. At least one vacuum switch is installed in the region between two gate valves. Gate valve Vacuum switch VSWs detect pressures higher than 1 Pa. Ion Pump

9 Interlock Logic (CCG) CCG E00201 HV on/off request The CCG usually emits gases at the beginning of discharge. The interlock logic has a delay time of 60 seconds. TIMER T sec. (close after 60 sec.) X00301 vacuum switch status E00201 HV on/off request X00317 discharge status Y00601 HV output The relay of vacuum switch status is closed when the pressure is less than about 1 Pa. T00201 delayed timer status Schematic diagram of ladder program The CCG controller returns normal discharge status when the pressure is less than about 10 3 Pa. Meaning in Ladder sequence program E: shared relay, I: internal relay, X: digital input relay, Y: digital output relay, L: FA Link relay, U: UNIWIRE relay, T: delayed timer relay

10 Interlock Logic (Steady state, Gate valves) In the steady state, where some of CCGs in the region operate stably, it becomes possible to apply HV to ion pumps and to activate NEG pumps. steady state Without any request to open, the valve remain in close position. E04001 E04101 I00301 L00002 Y open request close request steady state steady state next door open Gate valve

11 Interlock Logic ( Ion pump and NEG activation) When the pressure in the region gets worse in cases, the HV of CCGs is turned off at first. Then the status is no longer a steady state, and the HV of ion pumps and the heater power for NEG activation are turned off immediately by the interlock logic Ion Pump I00301 steady state X00301 vacuum switch status I00301 steady state X00529 E00501 interlock kill request magnets state HER only E00701 restrict output request Y00813 ion pump HV ready These relays kill the request to stop the IP baking and the NEG activation process irrespective of CCGs status. U00001 NEG activation ready NEG X00301 vacuum switch status E00601 interlock kill request This relay inhibits the output from power supplies for NEG activation. It will be used for the case where the beam pipe is exposed to air for maintenance, for example.

12 A procedure of the vacuum start up Start rough pumping with a turbo molecular pump (0.26 m3/s for N2) and a scroll type dry pump (0.2 m3/min) Check the vacuum switch status TMP HV is applied to CCGs and ion pumps in the region Scroll Start baking of IPs for 1 2 days Activate NEG pumps with a pattern operation for days Target pressure is less than 1E 7 Pa after the NEG activation

13 Typical trend of pressures in a region between two gate valves after IP baking and NEG activation NEG activation end NEG activation start This point shows the pressure values is less than 1E 7 Pa. Baking of IP start The test result was good

14 High speed data acquisition of CCGs Problem pressure values The pressures are usually recorded every several seconds by CCGs located every 10 m in the ring. In an accidental case, therefore, it is sometimes difficult to localize the leak point where the pressure must have risen at first. Concept of solution High speed recording of pressures for at least several minutes before the accident will help the identification of problem. Request from solution Assuming that the propagation speed of pressure rise is same to that of sound (~350 m/s), the frequency of data acquisition of 35 Hz or more is required for every CCG. We chose 100 Hz scanning!

15 What s each crio doing Role sharing of high speed data acquisition crio AI(CCGs pressure value) D11 D10 D12 D1 D2 KEKB MainRing D3 D4 D5 CPU FPGA:Scanning cycle of 10 ms Real Time(RT) OS :Make from accumulated data with the time stamp to the array of circular buffer. Ethernet D9 D8 D7 D6 There are twelve crio in KEKB. These crio connect to the control network. crios synchronize with a NTP server WindowsPC:Monitoring event triggers. Analyzing pressure data from memory of crios.

16 Flow of the high speed data acquisition (1) The data acquired every twenty minutes are stored in the memory of the crio as the circular buffering system until the trigger is generated. (2)If the first signal of the pressure rise is excited as the trigger at some stations, the signal is provided to other stations. (3)After the trigger is generated, the data of the pressure, with time stamp for 5 minutes before entering the trigger and for 15 minutes after entering the trigger, is created on the each crio as text file. (4)The signal as the trigger is monitored by the alarm system. When the operator notice exciting the signal, the operator can get the data from the crio. The test at 2 stations is on the way. It is difficult to establish both RT, which runs CA Server, and FPGA.

17 Conclusions PLC based IOC was applied to upgrading the vacuum control system of SuperKEKB Consolidation of IOC and PLC considerably simplified the configuration of front end control The test of the control system has been succeeded according to the normally closed interlock logic. High speed data acquisition of CCGs pressure values is built and under test now.

18 Thank you for your attention