Planned material irradiation capabilities of IFMIF-DONES

IFMIF-DONES (International Fusion Materials Irradiation Facility - DEMO-oriented Neutron Source) is currently being developed in the frame of the EUROfusion Early Neutron Source work package (WPENS), based on the results achieved in the ongoing IFMIF/EVEDA (Engineering Validation and Engineering Design Activities) project by Japan and Europe in the frame of the Braoder Approach (BA) agreement. The neutron source's limited product of “irradiation volume × neutron fluence” on one hand and the large potential test matrix (defined by number of material grades, test types, irradiation- and test temperature levels and damage dose levels) on the other hand, require a careful selection of test conditions by collaborative effort of the communities of DEMO designers, fusion materials science and the irradiation facility designers. This paper describes achievable irradiation conditions in the High Flux Test Module (HFTM) of IFMIF-DONES, characterized by levels and gradients of irradiation temperatures and nuclear responses (dpa, H and He production). The HFTM development focuses on 9%-Cr Reduced Activation Ferritic Martensitic steel irradiations, but also the possibilities of tungsten and copper alloy irradiations are explored. Possible specimen arrangements and issues of the Small Specimens Test Technique are also discussed

The duration of viral suppression during protease inhibitor therapy for HIV-1 infection is predicted by plasma HIV-1 RNA at the nadir

Objective: To determine markers that are associated with the durability of virologic response to therapy with HIV protease inhibitors in HIV-infected individuals. Design: This study encompassed two retrospective analyses of the duration of virologic response to protease inhibitor therapy. The first analysis included 29 patients receiving either monotherapy or combination therapy with the protease inhibitor ritonavir whose plasma HIV RNA levels rebounded from the point of greatest decline with mutations associated with resistance to ritonavir. The second analysis included a cohort of 102 patients who initially responded to randomized treatment with either monotherapy with ritonavir or combination therapy with ritonavir and zidovudine. Methods: Durability of response was defined as the time from the initiation of therapy to the point at which plasma HIV RNA displayed a sustained increase of at least 0.6 log10 copies/ml from the nadir value. In the first analysis, durability of response was analyzed with respect to baseline HIV RNA, HIV RNA at the nadir, and the drop in HIV RNA from baseline to the nadir. In the second analysis, time to rebound was examined using Kaplan-Meier analysis, stratifying by either baseline HIV RNA or HIV RNA at the nadir. Results: In both analyses, the durability of response was not highly associated with either baseline RNA or the magnitude of RNA decline from baseline. Instead, a strong relationship was observed between the durability of response and the nadir plasma HIV-1 RNA value (P < 0.01). The nadir in viral load was generally reached after 12 weeks of randomized therapy. Conclusions: Viral RNA determinations at intermediate timepoints may be prognostic of impending virologic failure of protease inhibitor therapy. Therapeutic strategies that allow intensification of initial antiretroviral regimens in the subset of patients with incomplete virological response before the emergence of high level resistance should be investigated

LIPAc RF power system: design and main practical implementation issues

The Linear IFMIF (International Fusion Materials Irradiation Facility) Prototype Accelerator (LIPAc) is a 9 MeV, 125 mA, continuous wave (CW) deuteron accelerator aimed to validate the technology for the IFMIF accelerators. The construction of LIPAc, which is currently the most powerful deuteron accelerator in the world, has been carried out under the Broader Approach (BA) Agreement between EU and Japan, and it is located at Rokkasho (Japan). CIEMAT is one of the five European Institutions that has participated in the design, manufacturing and commissioning/operation of the main accelerator components, among them, the Radio Frequency Power System (RFPS).The RFPS contains all the equipment necessary to generate the required RF power to feed the LIPAc cavities. These cavities demand eighteen RF power chains at 175 MHz being distributed as follows: eight 200 kW tetrode-based chains for the Radiofrequency Quadrupole (RFQ), two 16 kW solid-state chains for the re-buncher cavities, and eight 105 kW tetrode-based chains for the Superconducting RF Linac Half-Wave Resonators.The design of the RFPS main components is presented in this paper, including the tetrode-based chains, the Solid-State Power Amplifier (SSPA) for the re-buncher cavities, the High Voltage Power Supplies (HVPSs) for the final amplifiers anodes and the RF water cooling system. Additionally, the main difficulties encountered during the first months of the RFPS commissioning and operation will be described, together with the applied improvements

Integration of 175 MHz LIPAc RF system and RFQ Linac for Beam Commissioning

The eight-chain RF system and radio frequency quadrupole (RFQ) linac were successfully integrated at the facility of the Linear IFMIF Prototype Accelerator (LIPAc). We achieved an unprecedented high current deuteron beam up to55 mA in pulse operation (300 μs, 1 Hz). The keys of the success were (1) understanding reflected power from RFQ to RF system, (2) tuning each RF chain individually, (3) intensive RF conditioning for holding the stable RF power in the RFQ, and (4) optimizing the beam loading compensation control. Interestingly, the reflection at the breakdown in RF conditioning was higher than an estimation and reached up to 600 kW so far. In order to avoid damage on tetrodes by the high reflection, the impedance of each circulator was accurately adjusted

Functional Overview of the RF Power System for the LIPAc RFQ

International audienceDesign, development, manufacturing, and test activities of the RF power system (RFPS) for Linear IFMIF Prototype Accelerator (LIPAc) were completed in Europe. Installation and commissioning activities were carried out at the International Fusion Materials Irradiation Facility-Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) site in Rokkasho, Japan. Challenging IFMIF requirements led to a number of innovations during design and development. Commissioning required a major effort on calibration and fine setting and led to development of new functionalities. The RFPS was validated under full power and 125-mA deuteron beam loading conditions, in the radio frequency quadrupole (RFQ), demonstrating good performance. This article is an overview about how technical challenges impacted the prototype RFPS design and its functional evolution during commissioning, cavity conditioning, and beam operation of the RFQ

RFQ Commissioning of Linear IFMIF Prototype Accelerator (LIPAc)

The IFMIF project aiming at material tests for a future fusion DEMO reactor is under the EVEDA phase in the BA Agreement of fusion program between Japan and EU. As the accelerator activity, the installation and commissioning of the Linear IFMIF Prototype Accelerator (LIPAc) is at the second stage of demonstration of the feasibility of the low energy section of an IFMIF deuteron accelerator up to 9 MeV with a beam current of 125 mA, CW. The installation of injector, RFQ, MEBT, D-Plate and LPBD for LIPAc with 8 coaxial high-power transmission lines and RF power system was just done in 2017 at Rokkasho, Japan. After that, the RF conditioning of RFQ for beam commissioning is underway. The beam commissioning of RFQ with H+/D+ and the acceleration demonstration up to 5MeV-125mA-0.1% duty cycle with D+ will be done

Overview of the Validation Activities of IFMIF/EVEDA: LIPAc, the Linear IFMIF Prototype Accelerator and LiFus6, the Lithium Corrosion Induced Facility

In this report, the latest results of the validation activities of the IFMIF/EVEDA project under the Broader Approach agreement are overviewed. For the Linear IFMIF Prototype Accelerator (LIPAc) to demonstrate the 9MeV/125mA D+ beam acceleration, the beam qualification study of the injector was completed with the emittance of 0.16 pi mm mrad smaller than required 0.3 pi mm mrad, and the maximum vane voltage in the RFQ cavity was achieved at 143kV exceeding the required 132kV. These components and other subsystems of LIPAc are ready to inject the beam to RFQ to provide the 5MeV D+ beam. The Superconducting RF linac necessary for the 9MeV D+ beam is close to the end of manufacturing phase to start its final assembly in Rokkasho. For the liquid lithium loop activities, 4,000 hours lithium corrosion test of the Reduced Activation Ferritic/Martensitic steels using the LiFus6 were completed and verified that the corrosion rate can be kept under control and well below the requirement of 1 micro-m/y, after achieving a good purity of lithium, < 30ppm N