Radio Frequency (RF) System and RFQ cavity

RF injection in the RFQ cavity up to 5% Duty Cycle (DC) was completed and conditioning up to 10%DC has now started with remote assistance by INFN. The conditioning reached stable 6,7%DC. Wednesday a low water coolant flow rate in HVPS (High Voltage Power supply) 3A appeared again: it was not possible to adjust the mass flow rate between the main leg and the HVPS leg of the RF WCS (Water Colling System) and reach a stable regime for the WCS, and the operation was stopped. Impurities have been found in the filters at the entrance and the exit of the HVPS. An investigation on the root cause is on-going as well as an accurate cleaning. The team is working hard to resume RF-RFQ conditioning ASAP.

Medium Energy Beam Transport (MEBT)

The conditioning of the bunchers started. CW RF power was injected into the buncher #1, by following the buncher conditioning procedure and a cavity voltage of 105 kV (nominal is 350kV) was achieved.

Beam Dump

The water circulation including the Beam Dump cartridge in Mode 1 (main operational mode during beam operation) was stable. The water treatment lines are running: on the one hand the decrease of O2 is monitored, on the other hand for the first time under Mode 1 operation the pH increase was succesfully achieved by chemical injection.

During the forced stop of RF-RFQ conditioning the vault could be open and the final alignement survey of the BD cartirdge was performed, confirming that the position is within the prescribed tolerances.

Control System

The installation activities of the MPS (Machine Protection system) cables for the common chiller were completed.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Injector

The injector conditioning using 6mm Plasma Electrode is currently on-hold waiting for the procurement of the cooling plates of the Power Supplies of the two Solenoid magnets. The plasma conditioning is on-going during the day when the vault is closed, and every night and weekend.

Radio Frequency (RF) System and RFQ cavity

RF injection in the RFQ cavity up to 5% Duty Cycle (DC) was completed and conditioning up to 10%DC has now started with remote assistance by INFN. The RF system is stable and no major event are observed. In the evening the system is let for night conditioning to NAT operators, while during the day time the on-site experts move to higher DC following the procedure defined with INFN requiring always tuning/adjustment of the system: for example the fine tuning of the mass flow rate balance among HVPS (High Voltage Power Supplies) and RF modules was necessary one day this week.

Medium Energy Beam Transport (MEBT)

The Personal Protection System (PPS) interface tests with the bunchers SSPA (Solid State Power Amplifiers) were successfully completed and the RF condition of the buncher cavities was started this week and is currently on-going.

Beam Dump

After the completion of the connection of the cooling loop to BD cartridge in the vault, the cartridge was successfully filled with water and the BD skid was successfully run in the two operational modes to be used for beam operation. Achieving the water circulation in the BD cartridge is a major achievement for the project and for the accelerator community worldwide!　

This could be achieved only thanks to the strenuous support of CIEMAT experts connected remote daily with Rokkasho starting from 7 am CEST and the on-site team providing an extensive support to CIEMAT experts allowing a wide amplitude of work although the time zone difference between Europe and Japan!

OPI of the BD cooling skid. It can be noticed that:

• The main pump of the cooling skid BWP01 is running at nominal speed (60Hz achieving 108m3/h
• The pump of the water treatement line (ph corection) BWP04 is operational, as well as the deareation loop (BAC01 vacuum pump).

Control System

The integration in EPICS of the MPS (Machine Protection System) signal from the Common Chiller is on-going. The enhancement of the OPI from the new CCR (Central Control Room) is showing good progresses.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Injector

The injector conditioning using 6mm Plasma Electrode is currently on-hold waiting for the procurement and repair of the cooling plate of the Power Supply of the Solenoid 1. The hardware delivery is planned by last week of June.

Radio Frequency (RF) System and RFQ cavity

In the last week the accelerator vault was open in the day time for the on-going activities on the HEBT (High Energy Beam Transport) and BD (Beam Dump).

RF injection in the RFQ cavity was resumed daily after 5PM when the vault could be closed. During the night the RF-RFQ injection was monitored by NAT operator and injection was mostly stable at around 5% duty cycle, without major disruptions. RF team checks during the injection focused on the stability, noise behaviour and circulator controllability.

The repair of the flowmeter of the cooling line of one of two Solid State Power Amplifiers (SSPA) has been completed.

Beam Dump

The alternative chemical for pH control (AM-490) was delivered and the first circulation tests with oxygen control (10 ppb is not reached yet) and pH control (using AM-490) were done with remote participation from CIEMAT.

The connection of the cooling loop to BD cartridge was completed in the vault (a temporary by-pass in front of the cartridge was installed so far) and filling of the entire loop including the cartridge is currently on-going. Circulation tests including the cartridge are planned starting form next week.

Control System

Connectivity checks for MPS/PPS (Machine Protection System/Personal Protection system) with HEBT/BD LCS (Local Control System) are on-going. Efforts focused on the Lead shutter.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Injector

The signs of corrosion that occurred in the cooling plate of the Power Supply of the Solenoid 1 were repaired and water circulation restarted. However the cooling plate is degrading fast and procurement of new cooling plates started. It is under assessment when the injector conditioning using 6mm Plasma Electrode can resume.

Radio Frequency (RF) System and RFQ cavity

RF water cooling system was recovered after replacement of the resins in the ion exchange unit. The water quality will be monitored closely during start-up and operation of the RF system. Also for the RFQ skid a rigorous continuous monitoring has been started.

RF injection in the RFQ cavity was resumed mid of this week. After the start-up checks and with the RF-RFQ injection stable around 5% duty cycle, it is planned to let the conditioning running during the night this Friday and then over the weekend.

The repair of the flowmeter of the cooling line of one of two Solid State Power Amplifiers (SSPA) is ongoing (spares have been shipped from the supplier in EU). The MEBT bunchers conditioning will resume after mid-May.

Medium energy Beam Transport (MEBT), MEL (MEBT Extension Line), HEBT (High Energy Beam Transport)                                                                                                                                       

The polarity checks of quadrupole and steering magnetic fields was conducted systematically and successfully completed.

Beam Dump

With strenuous support of CIEMAT team and daily remote sessions the Local Control System integration activities for the BD cooling skid is now almost completed. It was possible to perform first trials to run the BD cooling skid in automatic operation (under local and remote control). The two main pumps of the BD skid are fully operative with pressure and flow autoregulation.

The oxygen control loop was continuously running for about 40 hours to check content reduction, system/control stability and the “long-term” operation (we struggle to reduce oxygen concentration below 90 ppb for reaching at the target value of 1 ppb).

Efforts continue now for debugging controllers, upgrade of the OPI to include all functionalities and completion of MPS-PPS tests.

Control System

Elog server was migrated to DMZ server, dedicated for all services allowing remote participation of EU expert, from LIPAc technical net. Procedure to allow access from internet through SSL-VPN is on-going.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Injector

The deuteron beam extraction using 6mm Plasma Electrode was paused to fix a sign of corrosion that occurred at the cooling panels in the cubicles of the Power Supplies of the LEBT (Low Energy Beam Transport). The cubicles are located in the RF area, far from the accelerator vault. The corroded part was fixed and an identical cooling panel is being prepared for substitution in the near future. The intervention will be completed on Monday next week and injector conditioning will be resumed.

In VAC02 sector vacuum chamber (placed after the LEBT, at the RFQ entrance) the installation of the new turbo pump and scroll pump was successfully completed.

Radio Frequency (RF) System and RFQ cavity

After the individual tests carried out in the last weeks, the new predrivers have been installed on all RFQ-RF chains. Minor adjustment of the LLRF output level will be necessary.

RF injection in the RFQ cavity was paused at the end of last week as the quality of the cooling water in the RF skid experienced a quick degradation in resistivity. A quick recovery action is on-going and new ion exchange resins should be delivered end of this week for a replacement planned next week. RF injection in RFQ cavity is planned to resume next week.

In the cooling line of one of two Solid State Power Amplifiers (SSPA) the flow meter was disassembled, inspected and cleaned. It was confirmed that a part of flow meter was broken.

In the RFQ cavity all the cryopump groups were regenerated, however one compressor showed higher temperature (~17K) and was stopped. Despite maintenance was carried out on site by the supplier very recently, they suggest to replace a gasket. Analyses are carried out to understand the issue and take actions.

In the RFQ cooling skid the PH of water resulted unexpectedly low, 5.5, which probably indicates a degradation of the demineralizing beds. An intervention was performed this week to check the filters, and two flowmeters. Additionally the RFQ skid was completely drained and refilled with ultrapure water. The PH is now 7.2. Sample of water will be measured weekly until the summer maintenance.

Although a deep maintenance was carried out on the cooling systems in last year long term maintenance, a deep analysis of the recent events is carried out: countermeasures are taken immediately to operate safely the system and corrective measures are planned for the next long term maintenance (starting August 2021).

Medium energy Beam Transport (MEBT) and MEL (MEBT Extension Line)              

MEBT vacuum is stable at 1e-9 mbar. MEL vacuum was fully recovered after the intervention to install the RGBLM (Residual Gas Bunch Length Monitor) sensor. In the MEBT skid one conductivity sensor and filter were replaced.

Beam Dump

The functional check of the oxygen control loop by monitoring the decrease in oxygen concentration under water circulation (bypassing the BD cartridge itself in the vault) is on-going. The remote sessions with CIEMAT for commissioning and debugging the BD skid control system are on-going (daily remote sessions are carried out!).

Beam Instrumentation

After completion of the installation of the RGBLM sensor in the MEL, the High Voltage checks in vacuum are on-going.

Control System

The new RFQ couplers temperature measurement system was integrated into the RFQ LCS (Local Control System) with the remote support of INFN and operational ?

IT tools for allowing remote participation for RFQ conditioning above 10% of Duty Cycle and for the beam operation are under preparation.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Injector

The proton beam characterization with the 6 mm Plasma Electrode is on-going. The effect of Kr gas injection for controlling the space charge force and reducing the emittance is under investigation. The total extracted beam current achieved so far of 10 to 40 mA can be used for injection in the RFQ. The fractions of proton in the extracted beam are 50% @ 10 mA and 75% @ 30 mA.

Radio Frequency (RF) System and RFQ cavity                                                             

The start-up of the RF system continued. The damaged MicroBox PC used in the RF Water Cooling System (WCS) was repaired: monitoring of the WCS status is essential to hand over to NAT operator the conditioning during the night at low DC. The scheduled tests of the new predrivers continued and now 3 out of 10 have been successfully tested (each test lasts ~8hours). During injection trials into the RFQ cavity the RFPS experienced interlocks and several measures have been already taken: the Protection System (PSYS) of the RF chain 4B has been replaced with a spare, the formerly exchanged PSYS of chains 1B and 3B have been restored, and current instabilities in the circulator temperature compensation coil control (VAT10) are investigated.

Two flowmeters in the RFQ skid showed instabilities and triggered frequent interlocks: short term counter measures have been taken and an intervention on the RFQ skid is being carefully planned (most likely not necessary before next scheduled maintenance).

Thanks to all the efforts of the RF team, the RFPS system is now stable enough and it is planned to handle over soon the system to the NAT operator and start conditioning during the night (at DC<5%).

Beam Dump

The water circulation tests into the oxygen control loop and into the water conductivity control loop are on-going in manual operation mode. This week was fully packed of remote sessions with CIEMAT support to update and debug the BD skid LCS and be able to switch soon the skid to automatic mode.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Injector

After the completion of the PPS test (for the authorization to proceed with the beam extraction), the proton beam extraction has started with the Plasma Electrode having a 6 mm hole. The ramp-up was rather quick: 10-40 mA of proton beam at 5-10% duty cycle were achieved, with good stability and good beam emittance. The Injector is operative from the Central Control room.

Radio Frequency (RF) System and RFQ cavity                                                             

The start-up of the RF system with the calibration of the LLRF (Low Level RF) and the RF chains continued. The check of RF noise issue on the RF system components was systematically investigated; the situation is now improved thanks to remedial actions quickly implemented: grounding meshing is being improved and the newly installed PSYS-LLRF interlock circuit has been modified to inhibit the EMC perturbation. A MicroBox PC used in RF Water Cooling System (WCS) was damaged and it is being replaced: monitoring of the WCS status is essential to hand over at low DC to NAT operator the conditioning during the night. The planned activities to integrate the new RF coupler temperature monitor into the LCS started (remote sessions with INFN took place and are planned).

RF injection trials in the RFQ cavity were successfully carried out for the first time from the Central Control Room (CCR)! During RF injection the RFQ vacuum was stable and the temperature rise at the RFQ couplers was <1°C.

Beam Dump

As part of the BD skid commissioning, the functionality of the recently modified deaeration loop has been confirmed for the first time: under active water circulation in the BD skid the water conductivity was lower than 1uS/cm; operating the vacuum pump of the deaeration loop the dissolved oxygen was decreased from ~2000ppb to ~1600ppb in 20 min.

Currently CIEMAT support is focused on solving PLC issues to adjust sensors and flowmeters calibration and allow the pumps to work in automatic mode.

Beam Instrumentation

After delivery onsite of all the components, the final modification of the RGBLM (Residual Gas Bunch Length Monitor) was completed and the refurbished sensors is now ready to be installed in the vault. The intervention is planned in the week from 29^th of March to 2^nd of April.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Global Alignment survey

More details on the realignment of the second solenoid magnet (SOL2) of the LEBT (Low Energy Beam Transport) to the entrance of the RFQ completed last week: the achieved tolerance is within 0.1 mm. It is planned to analyse the effects of this change and the measured RFQ-MEBT misalignment by beam dynamics simulation. This will provide key information for the realignment of RFQ-MEBT during the summer maintenance.

Injector

This week the injector vacuum was resumed and insulation test for chopper were completed successfully up to 10 kV. The PPS test for starting plasma and HV conditioning were carried out beginning of the week. HV conditioning of the beam source was completed up to 100kV.

Proton extraction started with the initial main scope to confirm the beam characteristics with the re-installed 6mm plasma electrode.

• Duty cycle: 10% (10ms/100ms)
• Red: Total extracted current (I_ext): 40mA
• Yellow: Faraday cup signal (I_FC)
• Blue: Current of repeller PS (I_repeller)
• Green: Voltage of repeller PS (V_repeller)

Radio Frequency (RF) System and RFQ cavity                                                             

The start-up of the RF system with the calibration of the LLRF (Low Level RF) and the RF chains continued. The check of the RF noise issue on the RF system components continued all the week by increasing the pulse length. The newly installed PYS-LLRF interface to improve the time response of the fast interlock is also improved to cope with spurious interlock generated by the noise issues. During RF injection trials into the RFQ up to 8ms at 1Hz and 128kV were achieved. The RFQ cavity behaviour was good (no instabilities, no interlocks triggered) and up to 4-5% duty cycle no effect was observed on the couplers temperatures. The planned activities to integrate the new RF coupler temperature monitor into the LCS started (remote sessions with INFN are foreseen).

Beam Dump

As part of the BD skid commissioning, the main pump of the BD skid is now operative in manual mode. Circulation in the loop up to the vault and the decay coil was started. It has to be highlighted the remarkable and strenuous effort provided by CIEMAT experts to support remotely the BD skid commission and for solving the LCS and PLC issues.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Global Alignment survey

The realignment of the second solenoid magnet (SOL2) of the LEBT (Low Energy Beam Transport) to the entrance of the RFQ was completed this week.

Injector

Following the decision taken earlier in February at management level, at the beginning of this week (before starting the realignment work) the Plasma Electrode (PE) currently installed in the Injector, with a diameter of 11mm, was changed with a PE of 6mm. Also, in the LEBT the chopper was reinstalled after the refurbishment and checkout tests performed in the last months.

Radio Frequency (RF) System and RFQ cavity                                                             

The start-up of the RF system with the calibration of the LLRF (Low Level RF) and the RF chains continued. RF noise issues are currently investigated for flow meters, PSYS-LLRF interface and other interlock signals. During injection in the RFQ cavity 150us/100 Hz @ 132 kV (D+ level) were achieved. The training on the operation of the Solid State Power Amplifiers (SSPA) for the MEBT (Medium energy Beam Transport) bunchers was completed.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc. 

Global Alignment survey

Additional alignment survey has been completed and the results shared and thoroughly discussed. The realignment of the second solenoid magnet (SOL2) of the LEBT (Low Energy Beam Transport) to the entrance of the RFQ will be performed starting next week. The correction of the alignment between the end of the RFQ and the beginning of the MEBT (Medium Energy Beam Transport) will be performed in the next maintenance period and before starting high duty beam operation. Correction of the mismatch between RFQ and MEBT, considering the size of the RFQ, is challenging and laborious (detailed procedures will be prepared).

Radio Frequency (RF) System and RFQ cavity                                                             

The start-up of the RF system with the calibration of the LLRF (Low Level RF) and the RF chains continued. The installation of Low Pass Filters into the PSYS-LLRF (Protection System – Low Level RF) interface boards was completed. During first RF injections @ 132 kV, D+ level, noise issues on PSYS interlock and water flow meter appear when pulse length exceeds 250us and are under investigation. Check-out of the RFQ cavity with RF injection is pending the completions of these activities.

Beam Dump

As part of the BD skid commissioning, the update of the PLC software for the BD cooling skid is on-going with remote support by CIEMAT.

Disclaimer: the information reported is not meant to be technically complete and doesn’t cover all the activities currently carried out on LIPAc.