P. Garibaldi's scientific contributionswhile working at École Polytechnique Fédérale de Lausanne (Lausanne, Switzerland) and other institutions
Article: Tore Supra Team Members 1988-2008Abstract: None. Consists of a list of team members and affiliations.
- Abstract: A 70 keV 40 A hydrogen beam injector has been developed at Cadarache for plasma diagnostic purpose (MSE and charge exchange) on the Tore-Supra tokamak. This injector routinely operates with a large size ion source (the so-called Pagoda ion source) which does not completely fulfill all the requirements necessary for the present experiments. As a consequence, the development of a new ion source (called Cybele) has been underway whose objectives are a high accelerated proton fraction (>80%),... Show More
- Abstract: The main results of the Tore Supra experimental programme in the years 2007–2008 are reported. They document significant progress achieved in the domain of steady-state tokamak research, as well as in more general issues relevant for ITER and for fusion physics research. Three areas are covered: ITER relevant technology developments and tests in a real machine environment, tokamak operational issues for high power and long pulses, and fusion plasma physics. Results presented in this paper... Show More
- Abstract: Oversized waveguides allow to transmit high electromagnetic power, but require components able to filter the unwanted modal content unavoidably excited along their path. In this paper mode filters based on corrugations partially filled with absorbing materials are described; they have been studied aiming at optimizing their performance and overcoming their intrinsic limitations. More precisely the dependence of the filtering performance on various geometrical parameters is derived using... Show More
Article: Overview of JET results
- Abstract: In order to assist the design of the future ITER Lower Hybrid launcher, coupling codes ALOHA, from CEA/IRFM, TOPLHA, from Politecnico di Torino, and GRILL3D, developed by Dr. Mikhail Irzak (A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia) and operated by ENEA Frascati, have been compared with the updated (six modules with four active waveguides per module) Passive-Active Multi-junction (PAM) Lower Hybrid antennas. Both ALOHA and GRILL3D formulate the problem in terms of... Show More
- Abstract: The use of rectangular oversized waveguides in the Main Transmission Lines of the Lower Hybrid Current Drive (LHCD) system of ITER, requires to investigate the problem of bends. The principal specifications that characterize the oversized bend design concern the minimization of the reflection of the fundamental mode and the maximization of its transmission, limiting at the same time its coupling to spurious modes that could propagate at the operational frequency. In this paper, the... Show More
- Abstract: In the framework of the EFDA task HCD-08-03-01, the ITER lower hybrid current drive (LHCD) system design has been reviewed. The system aims to generate 24 MW of RF power at 5 GHz, of which 20 MW would be coupled to the plasmas. The present state of the art does not allow envisaging a unitary output of the klystrons exceeding 500 kW, so the project is based on 48 klystron units, leaving some margin when the transmission lines losses are taken into account. A high voltage power supply (HVPS),... Show More
- Abstract: Steady-state long pulse operation of tokamaks requires fully non-inductive current drive, thus an external current drive method. Lower Hybrid Current Drive is recognized as one of the most efficient technique used in the present day tokamaks. Progress of the conceptual design of the LHCD ITER relevant system is reported, as well as critical technology issues.
- Abstract: In the frame of the EFDA task HCD-08-03-01, a 5 GHz Lower Hybrid system which should be able to deliver 20 MW CW on ITER and sustain the expected high heat fluxes has been reviewed. The design and overall dimensions of the key RF elements of the launcher and its subsystem has been updated from the 2001 design in collaboration with ITER organization. Modeling of the LH wave propagation and absorption into the plasma shows that the optimal parallel index must be chosen between 1.9 and 2.0 for... Show More
- Abstract: Tore Supra routinely addresses the physics and technology of very long-duration plasma discharges, thus bringing precious information on critical issues of long pulse operation of ITER. A new ITER relevant lower hybrid current drive (LHCD) launcher has allowed coupling to the plasma a power level of 2.7 MW for 78 s, corresponding to a power density close to the design value foreseen for an ITER LHCD system. In accordance with the expectations, long distance (10 cm) power coupling has been... Show More
- Abstract: An innovative high efficiency neutral beam injector concept for future fusion reactors is under investigation (simulation and R&D) between several laboratories in France, the goal being to perform a feasibility study for the neutralization of intense high energy (1 MeV) negative ion (NI) beams by photo‐detachment. The objective of the proposed project is to put together the expertise of three leading groups in negative ion quantum physics, high power stabilized lasers and neutral beam... Show More
- Abstract: In the framework of the Broader Approach Activities, the EU will deliver to Japan the 18 superconducting coils, which constitute the JT-60SA Toroidal field magnet. These 18 coils, manufactured by France and Italy, will be cold tested before shipping to Japan. For this purpose, the European Joint Undertaking for ITER, the Development of Fusion Energy (“Fusion for Energy”, F4E) and the European Voluntary Contributors are collaborating to design and set-up a coil test facility (CTF) and to... Show More
- Abstract: First CW test bed, devoted for ion cyclotron resonance heating (ICRH), is being built at CEA Cadarache. It has been designed for testing the ICRH antenna sub assemblies under ITER relevant conditions (vacuum, cooling and RF).This paper presents a technical overview of these facilities and discusses their future operations in the framework of the ITER ICRH European R&D program.
- Abstract: A one year-long major upgrade of the 3.7 GHz Lower Hybrid Current Drive (LHCD) generator for the Tore Supra (TS) tokamak has been performed. It consisted in installing a first series of eight Thales Electron Devices (TED) 700 kW CW klystrons, new CW components and auxiliaries, and in modifying the transmitter control and protection software. Modifications and calibration of the sensors and the RF subsystems were completed as well. Finally, the RF power available in the generator has been... Show More
- Abstract: 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... Show More
- Abstract: In parallel to the direct contribution to the procurement phase of ITER and Broader Approach, CEA has initiated research & development programmes, accompanied by experiments together with a significant modelling effort, aimed at ensuring robust operation, plasma performance, as well as mitigating the risks of the procurement phase. This overview reports the latest progress in both fusion science and technology including many areas, namely the mitigation of superconducting magnet quenches,... Show More
- Abstract: It has been demonstrated that lower hybrid current drive (LHCD) systems play a crucial role for steady-state tokamak operation, owing to their high current drive (CD) efficiency and hence their capability to reduce flux consumption. This paper describes the extensive technology programmes developed for the Tore Supra (France) and the KSTAR (Korea) tokamaks in order to bring continuous wave (CW) LHCD systems into operation. The Tore Supra LHCD generator at 3.7 GHz is fully CW compatible, with... Show More
- Abstract: The next step after ITER is to demonstrate the viability and generation of electricity by a future fusion reactor (DEMO). The specifications required to operate an NBI system on DEMO are very demanding. The system has to provide a very high level of power and energy, ~100MW of D° beam at 1MeV, including high wall-plug efficiency (η > 60%). For this purpose, a new injector concept, called Siphore, is under investigation between CEA and French universities. Siphore is based on the stripping of... Show More
Publications citing this author (120)
[Show abstract] [Hide abstract] ABSTRACT: New nonresonance approach of photon accumulation in two spherical mirrors has been experimentally demonstrated. In this work, we have received a high accumulation coefficient and shown good effectiveness of this technique for creating photo neutralizer of negative ion beams. This efficiency in such concept is generally determined by reflectance mirrors and is practically not dependent of input emission quality and does not require high precision adjusting the optical elements.
- Creating such a system based on modern technologies is possible, but requires a developmental work of resonator design. Current achievements and problems in the investigations of the resonator circuits can be found in [5,6]. Nonresonance accumulation of photons can be an alternative way [7,8].
[Show abstract] [Hide abstract] ABSTRACT: The nuclear fusion research goal is to demonstrate the feasibility of fusion power for peaceful purposes. In order to achieve the conditions similar to those expected in an electricity-generating fusion power plant, plasmas with a temperature of several hundreds of millions of degrees must be generated and sustained for long periods. For this purpose, RF antennas delivering multi-megawatts of power to magnetized confined plasma are commonly used in experimental tokamaks. In the gigahertz range of frequencies, high power phased arrays known as "Lower Hybrid" (LH) antennas are used to extend the plasma duration. This paper reviews some of the technological aspects of the LH antennas used in the Tore Supra tokamak and presents the current design of a proposed 20 MW LH system for the international experiment ITER.
- A LH system able to deliver 20MW/CW has been proposed for the ITER tokamak . In this design, the antenna is made of 48 identical modules, each one independently fed by one 5 GHz/500 kW CW klystron: twelve in the horizontal direction and four in the vertical direction.
[Show abstract] [Hide abstract] ABSTRACT: In order to accumulate the research experience and technical reserves for future negative ion sources of nuclear fusion reactors, a prototype negative ion source is being designed and constructed at ASIPP with a reduced scale extraction area (166 cm² on the opening of 12 × 48 cm²). Based on the existing negative ion sources having the similar width, an external magnetic filter with permanent magnets is applied to the prototype negative ion source during the initial experiments. For the specific experiments of magnetic field dependence, an adjustable magnetic filter is required. Hence, the plasma grid current filter for short-pulse or long-pulse source and a combination filter using permanent magnets and plasma grid current are designed. The main design purpose is to produce a homogenous and sufficient filter field in front of the plasma grid, with the supply current as low as possible. The filter field distributions of these different magnetic filters are studied in detail by finite element method, especially on the plane paralleling with the plasma grid.
- This concept has been recommended to the ITER reference design, and will be further developed and tested on the ITER full size ion source and injector test beds at Consorzio RFX (SPIDER and MITICA). Unlike the transverse filter field in most of the negative ion source, a lateral filter field is generated in the large aspect ratio source for photoneutralizer-based injector at CEA-IRFM, by a pair of lateral electric coils winding around opposite sides of an iron rectangular frame. This field will also confine the electrons for plasma generation, and deflect the co-extracted electrons in the accelerator.
[Show abstract] [Hide abstract] ABSTRACT: This paper presents some innovative numerical techniques for the efficient treatment of non-linear magnetic materials in the evolution of plasma in thermonuclear fusion devices.
- Consequently, the numerical models of fusion devices may be computationally very demanding, so that resorting to fast and parallel techniques may be required. In this paper, we analyse the Joint European Torus (JET) tokamak, which poses the additional challenge of having an iron core made of a nonlinear ferromagnetic material. Consequently, the numerical tool that we useto describe the device has been enhanced so as to include also these materials.
[Show abstract] [Hide abstract] ABSTRACT: A new model-based controller for the magnetic flux profile in a Tokamak plasma was developed using a simplified model of the magnetic flux dynamics. This simplified model is based on physically relevant dynamics that take into account the distributed nature of the system. Shape constraints on the controlled inputs are introduced, representing the limitations on the shape of the current profiles deposed by non-inductive current sources on the plasma. Some simulation results are presented and discussed.
- Recent advances in steady steady-state profile control can be found for instance in [7, 10, 13, 14] for JET and DIII-D. Some reviews of Tore Supra feedback control achievements can be found in [4,8]. Yet most of these approaches are based on linear models (both discrete and distributed) identified from experimental data and are, therefore, very sensitive to operating conditions.
[Show abstract] [Hide abstract] ABSTRACT: The design and overall dimensions of a 5 GHz TE10–TE30 mode converter are presented. This mode converter is a RF element of a 20 MW CW lower hybrid system proposed for ITER. A low power mock-up of this device has been manufactured at CEA/IRFM and measured at low power. RF measurements indicate a return loss of 40 dB and a transmission loss of 4.78 dB ± 0.03 dB for the three outputs. The forward conversion efficiency from TE10 mode to TE30 has been measured from electric field probing to 99.9%. The good RF performances obtained validate the RF design of this element.
- rmined from integrated simulations of propagation and absorption of LH waves in ITER for several scenarios . These simulations showed that an optimum |n |, defined as a trade-off between maximizing the current drive efficiency and minimizing the power deposition in the H-mode pedestal, is found to be |n | = [1.9–2.0] with a flexibility of [1.8–2.2] [7,8]. * Corresponding author. E-mail address: email@example.com (J. Hillairet).
[Show abstract] [Hide abstract] ABSTRACT: In order to study the generation and extraction of negative ions for neutral beam injection application, a negative ion source is being designed and constructed at Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). Through a four electrode grids system inside the accelerator, a negative ion beam will be extracted and accelerated up to −60 kV on a reduced scale extraction area of 12 × 50 cm² (the area of PG apertures is 185 cm²). The beam optics is a key issue for the accelerator design, and greatly determine the source experimental performance in term of beam current, heat load on the grid, beam divergence, and so on. In this paper, the trajectories of electrons and negative ions were simulated in the electrode grids of the negative ion source. The filter capability of electron deflection magnet on the co-extracted electrons is evaluated and confirmed. The negative ion beam optics was designed according to the calculated results of beam divergence and beam radius along the beamlet in different acceleration voltages. The deflection effect of the electron deflection magnet on the negative ion beam was investigated in the single beamlet case and multi-beamlets case.
- Specifically, the negative ion source on the aspect of high-voltage holding is based on the R&D experience of the positive ion source, which has surpassed the design value of 80 kV on the test stand and stably operated on the neutral beam injectors for the Experimental Advanced Superconducting Tokamak (EAST). The beam optics determines the key parameters of obtained ion beam such as beam current, heat load on the grid and beam divergence. In this paper, the negative ion beam trajectories in the accelerator of the negative ion source at ASIPP are calculated by using a commercial program (COMSOL Multiphysics).