P. Garibaldi's scientific contributionswhile working at École Polytechnique Fédérale de Lausanne (Lausanne, Switzerland) and other institutions

Publications (23)

Publications citing this author (120)

    • 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: 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.
    Full-text · Article · Dec 2015 · Fusion Engineering and Design
    • A LH system able to deliver 20MW/CW has been proposed for the ITER tokamak [15]. 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: 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.
    Full-text · Conference Paper · Mar 2012 · Fusion Engineering and Design
    • 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)[19][20][21]. 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[22][23][24]. This field will also confine the electrons for plasma generation, and deflect the co-extracted electrons in the accelerator.
    [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.
    Full-text · Article · Dec 2016
    • Consequently, the numerical models of fusion devices may be computationally very demanding, so that resorting to fast and parallel techniques may be required[1]. In this paper, we analyse the Joint European Torus (JET) tokamak[2], which poses the additional challenge of having an iron core made of a nonlinear ferromagnetic material. Consequently, the numerical tool that we use[3]to describe the device has been enhanced so as to include also these materials.
    [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.
    Full-text · Conference Paper · Jun 2017 · Fusion Engineering and Design
    • 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: 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.
    Full-text · Conference Paper · Jan 2011
    • 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: julien.hillairet@cea.fr (J. Hillairet).
    [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.
    Full-text · Article · Mar 2012
    • 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)[8][9][10]. The beam optics determines the key parameters of obtained ion beam such as beam current, heat load on the grid and beam divergence[11][12][13][14][15][16]. 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)[17].
    [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.
    Full-text · Article · Apr 2017 · Fusion Engineering and Design