LIPAc maintenance activities are on-going. On-sites activities have never stopped, but they were slowed down during a period of recommended teleworking due to Covid-19 outbreak. It is not yet possible for EU experts to travel for supporting activities at the Rokkasho BA site.
The Medium-Energy Beam Transport extension line has been successfully manufactured and installed. It has been designed to transport the beam to the permanent Beam Dump at 5 MeV instead of the cryomodule. LIPAc is now upgraded into its future phase B+ (125 mA, D+, 5 MeV, high duty cycle) configuration, with its High Energy Beam Transport line and the Beam Dump.
Newly installed Medium-Energy Beam Transport extension line
Work is currently on-going with the following activities:
Licensing preparation with Japanese authorities;
Maintenance of LIPAc systems;
Start of a training campaign for operators and experts;
Setting remote participation tools to ease and increase participation of EU experts;
Resuming of the RFQ conditioning;
Preparation to resume operation with Phase B+ objectives.
During stop for the scheduled maintenance, a long-planned LIPAc Commissioning and Beam Operation workshop was organized at the Broader Approach Rokkasho site on Nov. 20-22. The workshop gathered again the LIPAc collaboration after the completion of the commissioning Phase B (5 MeV, 125 mA, D+, 0.1% DC, including the commissioning of the RFQ and buncher cavities, as well as a large part of the beam instrumentation).
Commissioning and Beam Operation workshop #02 session
The LIPAc team has been pleased to
welcome Dr. M. Munoz (ESS), Prof. E. Kako (KEK) and Dr. Y. Kondo (J-PARC) to
share valuable experience. During 3 days, the accelerator scientists and
experts from Japan and Europe exchanged about the operational aspects of the LIPAc:
Status, results, outcome and achievements
of the phase B
Difficulties and lessons learned
from commissioning and operation
Organization of the LIPAc Unit for
operation and maintenance
Coordination and tools for efficient
operation
Coordination and tools for efficient
maintenance
Furthermore, the steps ahead for
LIPAc were addressed, including:
On-going preparation of the beam transport lines for Phase B+ (5 MeV, 125 mA, D+, high duty cycle)
Detailed definition of the phase B+ Commissioning Plan
Preparation of the SRF Linac cryomodule assembly
The goal of the workshop is also to
strengthen the communication and team spirit among IFMIF/EVEDA collaborators
who are geographically distant in Europe and Japan. The conclusions
and actions identified by the chairman in each session will be gathered into an
action plan.
Attendees of the Commissioning and Beam Operation workshop #02
The 24th Project
Committee (PC#24) was held at Rokkasho Broader Approach Site on October 15 and
16. The project status and achievements were presented as well as the outlook
from phase B+ onward. The main update topics discussed were:
RF system improvement
Phase B milestone beam perveance record
Beam Dump installation resumed
Phase B end and the maintenance
period start
Technical difficulties
Next objectives towards continuous
wave operation
Objectives of High Energy Beam
Transport line and Beam Dump validation
Long-term improvement actions
Preparation of the Medium Energy
Beam Transport extension line
Status of superconducting solenoids
procurement for the SRF Linac Cryomodule
Preparatory status for the clean
room assembly of the Cryomodule
The action plan for 2020 was
presented for installation, maintenance and operation.
After the completion
of operation corresponding to the phase B, the maintenance activities have started
mid of August as planned alongside the preparation of the next phase: phase B+.
In this long maintenance period, it is important to carry-out both the curative
maintenance of components that were malfunctioning and the preventive
maintenance to ensure a better reliability and availability of the systems for the
next operation campaigns. The maintenance activities are planned targeting to
resume Injector continuous wave operation and Radio-Frequency Quadrupole (RFQ)
conditioning before end of 2019, so that LIPAc operation can restart in the
second quarter of 2020. In this first period higher priority has therefore been
assigned to the Injector and RF/RFQ systems maintenance.
LIPAc configuration in phase B+
Maintenance
activities of
the Diagnostics-Plate and of the vacuum systems have also started; maintenance
of the Medium-Energy Beam Transport line (MEBT) are planned in December. Specific
activities on the beam instrumentation will be carried out in November with EU
experts from CEA and INFN on-site. The final beam instrumentation checkout will
take place after the installation of the MEBT extension line.
3-dimensional view of the MEBT extension line for phase B+
The maintenance of the ancillaries is on-going and
many activities have already been completed, such as electrical network
distribution, secondary cooling system, Personnel Protection System, Accelerator
vault crane. The cryoplant maintenance activities will be carried out in the
first quarter of 2020.
The upgrade
of LIPAc into its future phase B+ configuration, with its High Energy Beam
Transport line (HEBT), is also the goal of this maintenance period. The MEBT
extension line has been designed to transport the beam at 5 MeV instead of
the cryomodule. It is composed of quadrupoles to focus the beam, steerers to
correct its trajectory, Beam Position Monitors to monitor the beam orbit, a
vacuum chamber to host a Residual Gas Bunch Length Monitor, Beam Loss Monitors
and turbo-pumps for vacuum pumping. The components of the MEBT extension line are
currently being procured or manufactured.
Alignment and connection work for HEBT
The Low Power Beam Dump which was used during
phases A and B will be removed. The HEBT is positioned in its final position together
with the Diagnostics Plate, and the LIPAc Beam Dump for full beam energy will
be connected to the beam line.
The deuteron (D+) beam commissioning has been ongoing
since two months, and we achieved a 125 mA beam acceleration by the Radio
Frequency Quadrupole (RFQ), and transported to the Low Power Beam Dump (LPBD)
on the 24th of July, 2019. The data was obtained in pulsed mode
operation of ion plasma source with 1 ms length and 1 Hz repetition
rate.
D+ Beam measurement along the LIPAc
The beam current range was varying from 50 to 140 mA at the
entrance of RFQ, and 90% transmission through the RFQ was measured for a maximum
current of 125 mA (measurement taken at the end of the beam pulse shape) and for
a rated RFQ cavity voltage of 132 kV.
D+ Beam characteristics
The detail of the accelerated beam characteristics is under
investigation and the commissioning phase is still ongoing.
This significant outcome demonstrates that all the components of the
LIPAc accelerator in the phase B configuration meet the design requirements. This
achievement gives us confidence for the future and the next step toward continuous
wave operation at 5 MeV with its high energy beam transport line.
The proton characterization at 2.5 MeV was completed on April 30, 2019
(Phase B1). During this phase, with an extracted current of 88 mA and 300
µs maximum pulse length from the injector, a maximum current of 57 mA was accelerated in the Radio
Frequency Quadrupole (RFQ) with a transmission of 93 % through RFQ and beam
transport line up to the Low Power Beam Dump (LPBD).
Summary of Phase B1 commissioning
The RFQ was conditioned for proton level operation, which
requires a field of about 70 kV to accelerate the protons. In the case of
the deuteron operation (next phase B2, and nominal condition of the machine),
the cavity needs to be conditioned to reach a maximum field of 142 kV. The
conditioning is still on-going to reach that field level with pulses up to 300 µs.
The Beam
Instrumentation has also demonstrated to be operational. Further improvements are ongoing which should ease beam operation and allow data analysis with
comparison to beam dynamics models.
SLIT (Ciemat)/ SEM Grid (CEA) Interceptive diagnostic measurement
As an example, the above figure on the left shows the
measurement of beam profiles, providing the shape of the beam. On the right,
the beam position in space is monitored.
