How to treat PETS. CTF3 operation made easy

Transcription

1 How to treat PETS CTF3 operation made easy PETS OPERATION on one page... 2 Introduction Scope... 3 Conditioning process (by automated software)... 3 General remarks, Safety... 3 Operation procedure... 4 Operational Tools... 5 Operations console PETSOP... 5 VISTAR... 5 OP Display... 7 ALARM program GHz RF Automatic Conditioning Application... 8 CTF3 Layout... 9 Further reading... 9 Expert list... 9 Failure modes Klystron trip Power converter failures Gun problems

2 1. PETS OPERATION on one page The CTF3 PETS operation is controlled from the operations console for the user petsop with the common operational password. The task of the PS complex shift team is to survey the CTF3 automatic conditioning outside normal working hours. The automatic conditioning program will switch on and off the beam. The beam presence can be seen on the CTF3 Vistar (see Figure 1), but the beam will temporarily disappear and should reappear. If it does not reappear for several minutes, check for problems. The most common problem is a trip of a klystron (CK.MKS02, 03, 05, 06, 07). To detect this, check the klystron status on the Vistar. All five boxes should be green. If one is not, follow the instructions in the section Klystron trip on page 10 to reset the klystron. You can avoid having to check Figure 1: Typical Vistar display yourself for problems if you set up an automatic message in the conditioning program: You can have an SMS sent to a given phone number in case of problems, so you will be automatically notified. Please refer to section 30 GHz RF Automatic Conditioning Application on page 8 for details. You will find more detailed information on the following pages. In case the problem is not a klystron trip, have a look in the ALARM program for possible causes. If you cannot resolve the problem, no further action is expected from you and the specialist will investigate later. Please note you actions, comments and problems in the CTF elogbook. Thanks a lot! - 2 -

3 2. Introduction Scope The R&D programme for the future CLIC linear collider requires an extensive testing of 30 GHz accelerating structures and RF components. The CTF3 test facility provides the electron beam to produce 30 GHz RF power in a special RF structure (PETS Power Extraction Transfer Structure) for these tests. In order to maximize the testing time with limited manpower, the operation will be surveyed by the PS complex shift team during nights and week-ends. The beam will be initially set up by the CTF3 specialists, the task of the operator is to check regularly the status of the beam and eventually debug certain problems. The conditioning itself is controlled from an automated program that handles the control of the 30 GHz RF parameters. In case of an irresolvable problem, no further action is required from the operator and the CTF3 specialist will diagnose the problem at his return. Conditioning process (by automated software) For the conditioning of the 30 GHz structures, the power and pulse length of the RF pulses have to be increased gradually while observing RF breakdowns and vacuum levels. Accordingly, the conditioning program disables the gun trigger in case of a breakdown, shortens the pulse length, enables the gun trigger and lengthens the pulse in steps again. The program also surveys the status of the klystrons that generate the RF power for acceleration and waits in case of faults. This means that there can be periods where no beam is present without any intervention required by the operator. Only if there is no beam for more than about 5 minutes, the operator needs to check if there is some faulty equipment that he can reset. General remarks, Safety If there is any indication that CTF3 is not running properly (like radiation alarms, high beam losses, etc.), do not hesitate to stop the beam. To do this, pause the automatic conditioning (see description page 8) and disable the gun trigger CX.SGUN (if you disable the trigger without pausing the automatic conditioning, it will re-enable the trigger). Alternatively, you can shut the first vacuum valve (CL.VVS01-32) from the CTF3 Access Program and an interlock will prevent the gun from pulsing

4 Operation procedure The beam will be set up by the CTF3 specialists. They will assure that the beam conditions are suitable for the RF conditioning. They will start the automatic conditioning program and the logging of the data. They will save the present settings of the machine to the reference settings. Finally they will inform the PS complex shift team that CTF3 is ready for being taken over by the CCC. From that moment, the operator should regularly check the presence of the beam on the CTF3 Vistar (see below) and/or set up the automatic notification in the automatic conditioning program. If there is an apparent problem or if the beam is absent for a period of more than 5 minutes, the operator can try to establish beam again. Failures and down-time should be noted in the CTF elogbook, together with the problems that one encounters to diagnose the failure, in the spirit of improving this documentation and increasing the efficiency of the PETS operation. The CTF3 specialist will inform the PS complex shift team when the supervision is not required any more

5 3. Operational Tools Operations console PETSOP The console manager has been configured for the 30 GHz ( PETS ) operation of CTF3 to show only these equipments that are used for PETS operation. The console manager is started by logging in as petsop (password like other operation accounts). The PLS USER normally used for PETS operation is SETUP. Several tools have been put in place to facilitate the supervision of the conditioning. VISTAR The Vistar displays an overview of the present status of the beam and the most critical elements in CTF3. In particular, it displays the beam current along the linac to the PETS power generating structure, the status of the klystrons, the bending magnet currents and the status of the gun (see Figure 2). It allows the operator to get a one-look view if the beam is present and permits a very first diagnostic of the most common failure (klystron trips). In case the Vistar stops updating, it can be restarted by left-clicking on the console background and selecting Restart -> Restart CTF3 Vistar. The Vistar video source signal is Video Source SE23 of the Media Center

6 Figure 2: Typical VISTAR display. The beam direction for the current readings is from left to right. The gun status will show Timing CX.SGUN disabled if the gun trigger has been disabled. Since the automatic conditioning program does this after a breakdown, this will occasionally happen. Only if there is another evident fault or if no beam is present for 5 minutes, an operator intervention is required. The beam current will always decrease from left to right and particularly the last BPM (that is located after the PETS structure) shows a smaller current due to losses in the PETS structure. The klystron status is green if the klystron is pulsing correctly. If the colour is different, please refer to the section below (page 10) to put back the tripped klystron in operation (K2 stands for CK.MKS02, etc.). The bending current shows the current acquisition of the required dipole bending magnets in the beam path. Open the working set STEERING in case of a zero current reading

7 OP Display The OP Display for CTF3 permits the operator to control the most critical items for CTF3 and also gives a view of the present operation. It is configured to show the beam current at the PETS structure and the RF signals of the klystrons and allows the control of the klystrons and the gun (see Figure 3). It can be started from the GENERAL tab of the operations console. Figure 3: Typical OPDISPLAY window The top left graph shows the beam current pulse before and after the PETS power production structure. The right graph shows the RF pulses of the 5 klystrons. All RF pulses should show a relative flat region around t=5000ns. The panels below show the gun equipment and the gun timings. CX.SGUN is the start timing, CX.TGUN is the end pulse trigger with their corresponding fine delays (CX.xGUN-F). The klystron panel shows the RF->Gun interlock CK.GUN-INHIBIT that prevents the gun from pulsing in case of klystron problem but also when a vacuum valve is closed. Finally, it contains the klystron control. ALARM program The ALARM program for PETS operation has been configured to display only the relevant equipments. Besides the Vistar, it is a good starting point to diagnose problems

8 Ideally, no alarm messages should be present except a warning for CL.VVS0132 (locked this can only be controlled from the Access Console) and messages for CK.AMPLMKS0x for being in local which is correct. If these equipments CK.AMPLMKS0x show an error PEI maximum a specialist intervention is required. 30 GHz RF Automatic Conditioning Application This program can be started from the Control menu in the console manager. It allows to start/stop the automatic 30 GHz RF conditioning and the expert can set the conditioning parameters. The feature used by the operator is the pausing of the conditioning by pressing the marked button in the application (see Figure 4) and the setting up of an automatic notification in case of problems. By clicking on the bell icon, one gets to the panel (Figure 5) where one can enter a phone number for an SMS to be sent to. Clicking on Activate switches this feature on. In this case, a message will be send if the conditioning has been not OK for 5 minutes or in case of errors. Do not forget to disable this feature when the CCC supervision stops, otherwise you will keep receiving messages! Figure 4: 30 GHz conditioning application - 8 -

9 Figure 5: Notification settings CTF3 Layout A layout of the CTF3 accelerator with the different girders from the gun to the PETS structure is available in the Console Manager under SYNOPTIC. Further reading CTF3 description CTF shutdown lecture 2006 CTF3 design report CLIC study web site Expert list For any further questions, you can contact one of the CTF3 specialists: Frank Tecker Alberto Rodriguez Roberto Corsini Steffen Döbert Peter Urschütz

10 4. Failure modes Problems can be detected and diagnosed by checking the Vistar, Alarm Display or Op Display. Klystron trip The most common failure is the trip of a klystron (Equipment name CK.MKS0x, x:2,3,5,6,7). These can be reset in most cases by the operator. (If all klystrons except MKS02 trip, there is a problem with a CTF3 water cooling station and an intervention by TS/CV is required. Please see with TI in this case. Once the water station problem is solved, you can restart the klystrons.) A certain sequence of commands has to be respected: First, lower the PFN Voltage of the klystron by 10 kv. Next, pause the automatic conditioning (see description above) and set CX.SGUN to Disable to stop the gun trigger. Depending on the present status of the klystron, follow the full action sequence to the bottom (to PULSING): Status Action OFF RESET HEATER (waiting time of 20min if the klystron was OFF) (The klystron should pass to status HEATER now.) HEATER RESET STANDBY (waiting time 120sec) (The klystron will pass to Status to-stby and should pass to STANDBY after a RESET once the waiting time has passed.) STANDBY RESET PULSING The klystron should pass to mode PULSING now. If this is not the case, you can try to set the klystron to HEATER and redo the full sequence. If the klystron still does not pulse, a specialist intervention is required. Since an interlock (CK.GUN-INHIBIT) prevents beam in this case, CTF3 will stay in a safe state. Then you will have to raise the PFN slowly (timescale ~1-2 min) to the previous value. Finally, you have to restart the 30 GHz conditioning program by pressing the PAUSE/START button there. This program should now enable the gun trigger again and the beam should appear

11 Power converter failures In case a power converter trips and the beam gets lost before reaching the end of the beam line, an interlock (CP.CPILOSS, see working set GUN- INTERLOCK) disables the gun trigger. Please check the power converters in the working sets FOCUSING (solenoids and quadrupoles) and STEERING (bending magnets and dipole orbit correctors). Gun problems If the gun is not pulsing, this can be due to external interlocks to the gun or due to the gun itself. - Make sure first that the gun timings CX.SGUN and CX.TGUN are enabled. If CX.SGUN is disabled, try to enable it. If it gets directly disabled again, this can be due to a software interlock (see Working set: GUN-INTERLOCK) or a 30 GHz RF breakdown event. - The interlock CK.GUN-INHIBIT (from the klystrons and a vacuum valve protection interlock) has to show status ON. If this is not the case, check the status of the klystrons and check if all the vacuum valves are open (Working set: VAC-VALVE_GAUGE). - If the gun equipment itself (CL.CTF3-GUN) shows a problem, pause the automatic conditioning program. Open the Sequencer Eqps program from the Sequence menu of the console manager. Select first the sequence Gun Off on the left panel and press the Start Sequence button. When the sequence has completed, select the sequence Gun On and start it. If the gun does not show the status Pulsing after the end of this sequence (takes about 2min), a specialist intervention is required