The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy and includes two experiments: MITICA, the full-scale prototype of ...the ITER heating neutral beam injector, and SPIDER, the full-size radio frequency negative-ions source. The NBTF realization and the exploitation of SPIDER and MITICA have been recognized as necessary to make the future operation of the ITER heating neutral beam injectors efficient and reliable, fundamental to the achievement of thermonuclear-relevant plasma parameters in ITER. This paper reports on design and R&D carried out to construct PRIMA, SPIDER and MITICA, and highlights the huge progress made in just a few years, from the signature of the agreement for the NBTF realization in 2011, up to now-when the buildings and relevant infrastructures have been completed, SPIDER is entering the integrated commissioning phase and the procurements of several MITICA components are at a well advanced stage.
Purpose: ATP-binding cassette sub-family C member 2 ABCC2; multidrug resistance–associated protein 2 (MRP2) and ABCC3 (MRP3) mediate
the elimination of toxic compounds, such as drugs and carcinogens, ...and have a large overlap in substrate specificity. We investigated
the roles of Abcc2 and Abcc3 in the elimination of the anticancer drug methotrexate (MTX) and its toxic metabolite 7-hydroxymethotrexate
(7OH-MTX) in vivo .
Experimental Design: Abcc2;Abcc3 −/− mice were generated, characterized, and used to investigate possibly overlapping or complementary roles of Abcc2 and Abcc3
in the elimination of MTX and 7OH-MTX after i.v. administration of 50 mg/kg MTX.
Results: Abcc2;Abcc3 −/− mice were viable and fertile. In Abcc2 −/− mice, the plasma area under the curve (AUC i.v. ) for MTX was 2.0-fold increased compared with wild type, leading to 1.6-fold increased urinary excretion, which was not seen
in Abcc2;Abcc3 −/− mice. Biliary excretion of MTX was 3.7-fold reduced in Abcc2 −/− but unchanged in Abcc2;Abcc3 −/− mice. The plasma AUC i.v. s of 7OH-MTX were 6.0-fold and 4.3-fold increased in Abcc2 −/− and Abcc2;Abcc3 −/− mice, respectively, leading to increased urinary excretion. The biliary excretion of 7OH-MTX was 5.8-fold reduced in Abcc2 −/− but unchanged in Abcc2;Abcc3 −/− mice. 7OH-MTX accumulated substantially in the liver of Abcc2 −/− and especially Abcc2;Abcc3 −/− mice.
Conclusions: Abcc2 is important for (biliary) excretion of MTX and its toxic metabolite 7OH-MTX. When Abcc2 is absent, Abcc3 transports
MTX and 7OH-MTX back from the liver into the circulation, leading to increased plasma levels and urinary excretion. Variation
in ABCC2 and/or ABCC3 activity may therefore have profound effects on the elimination and severity of toxicity of MTX and
7OH-MTX after MTX treatment of patients.
Since the signature of the ITER treaty in 2006, a new research programme targeting the emergence of a new generation of neutral beam (NB) system for the future fusion reactor (DEMO Tokamak) has been ...underway between several laboratories in Europe. The specifications required to operate a NB system on DEMO are very demanding: the system has to provide plasma heating, current drive and plasma control at a very high level of power (up to 150 MW) and energy (1 or 2 MeV), including high performances in term of wall-plug efficiency (η > 60%), high availability and reliability. To this aim, a novel NB concept based on the photodetachment of the energetic negative ion beam is under study. The keystone of this new concept is the achievement of a photoneutralizer where a high power photon flux (~3 MW) generated within a Fabry-Perot cavity will overlap, cross and partially photodetach the intense negative ion beam accelerated at high energy (1 or 2 MeV). The aspect ratio of the beam-line (source, accelerator, etc) is specifically designed to maximize the overlap of the photon beam with the ion beam. It is shown that such a photoneutralized based NB system would have the capability to provide several tens of MW of D0 per beam line with a wall-plug efficiency higher than 60%. A feasibility study of the concept has been launched between different laboratories to address the different physics aspects, i.e. negative ion source, plasma modelling, ion accelerator simulation, photoneutralization and high voltage holding under vacuum. The paper describes the present status of the project and the main achievements of the developments in laboratories.
The negative ion electrostatic accelerator for the neutral beam injector of the International Thermonuclear Experimental Reactor (ITER) is designed to deliver a negative deuterium current of 40 A at ...1 MeV. Inside the accelerator there are several types of interactions that may create secondary particles. The dominating process originates from the single and double stripping of the accelerated negative ion by collision with the residual molecular deuterium gas (≃29% losses). The resulting secondary particles (positive ions, neutrals, and electrons) are accelerated and deflected by the electric and magnetic fields inside the accelerator and may induce more secondaries after a likely impact with the accelerator grids. This chain of reactions is responsible for a non-negligible heat load on the grids and must be understood in detail. In this paper, we will provide a comprehensive summary of the physics involved in the process of secondary emission in a typical ITER-like negative ion electrostatic accelerator together with a precise description of the numerical method and approximations involved. As an example, the multiaperture-multigrid accelerator concept will be discussed.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM, UPUK
The integration of the heating and current drive (HCD) systems in the EU DEMO tokamak must address a number of issues, namely space constraints in the tokamak building, remote handling requirements, ...breeding blanket penetration, neutron and photon radiation shielding, compliance of penetrations of the primary vacuum with safety and vacuum criteria, and a large number of loading conditions, in particular heat, electromagnetic (EM), and pressure loads in normal and off-normal conditions. A number of pre-conceptual design options for the vacuum vessel (VV) port and the port-plug are under assessment and need to be verified against all requirements and related criteria. The identification of the functional (or physics) requirements of the HCD systems remains an on-going process during the pre-conceptual design phase, hence some initial assumptions had to be made as a basis for development of the design of the VV ports and the HCD port plugs.
The paper will provide an overview of present margins in the functional/physics requirements and the rationale behind the assumptions made in order to facilitate development of the pre-conceptual design options. Furthermore it will introduce the initial design concepts of the electron cyclotron (EC) Launchers and the neutral beam (NB) injectors integrated in equatorial ports. The NB duct design in DEMO and related issues such as transmission and re-ionization losses will be also addressed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The physics design of the accelerator for the heating neutral beamline on ITER is now finished and this paper describes the considerations and choices which constitute the basis of this design. Equal ...acceleration gaps of 88 mm have been chosen to improve the voltage holding capability while keeping the beam divergence low. Kerbs (metallic plates around groups of apertures, attached to the downstream surface of the grids) are used to compensate for the beamlet-beamlet interaction and to point the beamlets in the right direction. A novel magnetic configuration is employed to compensate for the beamlet deflection caused by the electron suppression magnets in the extraction grid. A combination of long-range and short-range magnetic fields is used to reduce electron leakage between the grids and limit the transmitted electron power to below 800 kW.
► Improvements to ITER accelerator voltage holding. ► Improvements to ITER negative ion source design. ► Improvements to ITER megavolt bushing. ► Improvements to beamline components. ► Accelerator ...design improvements.
The ITER 1 fusion device is expected to demonstrate the feasibility of magnetically confined deuterium–tritium plasma as an energy source which might one day lead to practical power plants. Injection of energetic beams of neutral atoms (up to 1MeV D0 or up to 870keV H0) will be one of the primary methods used for heating the plasma, and for driving toroidal electrical current within it, the latter being essential in producing the required magnetic confinement field configuration. The design calls for each beamline to inject up to 16.5MW of power through the duct into the tokamak, with an initial complement of two beamlines injecting parallel to the direction of the current arising from the tokamak transformer effect, and with the possibility of eventually adding a third beamline, also in the co-current direction. The general design of the beamlines has taken shape over the past 17 years 2, and is now predicated upon an RF-driven negative ion source based upon the line of sources developed by the Institute for Plasma Physics (IPP) at Garching during recent decades 3–5, and a multiple-aperture multiple-grid electrostatic accelerator derived from negative ion accelerators developed by the Japan Atomic Energy Agency (JAEA) across a similar span of time 6–8. During the past years, the basic concept of the beam system has been further refined and developed, and assessment of suitable fabrication techniques has begun. While many design details which will be important to the installation and implementation of the ITER beams have been worked out during this time, this paper focuses upon those changes to the overall design concept which might be of general interest within the technical community.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The negative ion accelerators that produce the high-energy particle beams for the neutral injection systems for the International Tokamak Experimental Reactor (ITER) also produce unwanted particles ...such as electrons. These electrons are emitted in a wide angular spectrum that allows some of them to directly intercept sensitive beamline components such as the cryogenic pumps. As the electrons are also subject to backscattering, indirect interception always occurs. In this article the electron spectra produced by the Heating Neutral Beam (HNB) and Diagnostic Neutral Beam (DNB) accelerators are calculated. It is shown that these are very different. It is proposed to install electron dumps in the beamlines to intercept electron power directed towards inconvenient places in the HNB and DNB beamlines.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
IRFM (CEA Cadarache) and JAEA Naka have entered into a collaboration in order to test a Single Gap, Single Aperture (SINGAP) H.P.L. de Esch, R.S. Hemsworth, P. Massmann, Updated physics design ...ITER-SINGAP accelerator, Fusion Eng. Des. 73 (2005) 329. accelerator at the JAEA Megavolt Test Facility (MTF) at Naka, Japan. Whereas at the CEA testbed the acceleration current was limited to 0.1
A, at JAEA 0.5
A is available. This allows the acceleration of 15 H
− beamlets in SINGAP to be tested and a direct comparison between SINGAP and Multi Aperture, Multi Grid (MAMuG) M. Taniguchi, T. Inoue, N. Umeda, M. Kashiwagi, K. Watanabe, H. Tobari, M. Dairaku, K. Sakamoto, Acceleration of ampere class H
− ion beam by MeV accelerator, Rev. Sci. Instrum. 79 (2008) 02C110. to be made.
High voltage conditioning in the SINGAP configuration has been quite slow, with 581
kV in vacuum achieved after 140
h of conditioning. With 0.25
Pa of H
2 gas present in the accelerator 787
kV could be achieved. The conditioning curve for MAMuG is 200
kV higher.
SINGAP beam optics appears in agreement with calculation results. A beamlet divergence better than 5
mrad was obtained.
SINGAP accelerates electrons to a higher energy than MAMuG. Measurements of the power intercepted on one of the electron dumps have been compared with EAMCC code G. Fubiani, H.P.L. de Esch, A. Simonin, R.S. Hemsworth, Modeling of secondary emission processes in the negative ion based electrostatic accelerator of the International Thermonuclear Experimental Reactor, Phys. Rev. ST Accel. Beams 11 (2008) 014202. calculations.
Based on the experiments described here, electron production by a SINGAP accelerator scaled up to ITER size was estimated to be too high for comfort.
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Negative ion based neutral beam injection (N-NBI) systems which produce powerful high energy hydrogen atom beams are currently used on fusion reactor devices for plasma heating and current drive. To ...produce sufficient negative ions (NIs), sources with a large surface area are needed for reactor relevant injectors. Plasma source non-uniformity is a recurring issue in the present N-NBI systems, it is mainly due to the transverse magnetic field (filter field) at the front of the source which generates plasma gradients. This paper presents experimental results on a large size arc driven ion source at CEA, called Cybele, the purpose of the experiment is to compare the plasma density distribution (uniformity) between two magnetic confinements, (1) the transverse (horizontal) magnetic filter which is implemented in the present negative ion (NI) sources and (2) a new concept based on the magnetic mirror principle. Experiments show that in Cybele the standard configuration with the horizontal filter field (1) leads to a significant vertical plasma drift with a measured plasma density seven times higher at the top of the source, while the source with the vertical field and mirror-like confinement (2) is vertically uniform within ±10% and can operate at very low filling pressure (0.1 Pa).
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