Peaked density profiles due to neon injection on FTU

Mazzotta, C.; Navarro, A. Bañón; Gabellieri, L.; Marinucci, M.; Pucella, G.; Told, D.; Tudisco, O.; Apruzzese, G.; Artaserse, G.; Sozzi, C.

doi:10.1088/0029-5515/55/7/073027

Cited by 16 publications

(15 citation statements)

References 19 publications

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“…The Phase -II plasma operations were resumed in February 2018 with circular hydrogen plasma in a Graphite limiter (toroidal belt limiter) configuration and continued to achieve plasma parameters close to design parameters. The Phase-II plasma operation of ADITYA-U has been focused on carried out the novel experiments including primary and secondary RE control [11 -12], Injection of SMBI during current flattop and disruption [13 -14], confinement improvement with Neon injection [15] with the execution of real time plasma position feedback control [16]. The consequences of these experiments are very promising and play a vital role in operation of large size fusion machine including ITER.…”

Section: Introductionmentioning

confidence: 99%

Overview of operation and experiments in the ADITYA-U tokamak

et al. 2019

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First indigenously built tokamak ADITYA, operated over 2 decades with circular poloidal limiter has been upgraded to a tokamak named ADITYA Upgrade for the purpose having shape plasma operation with open divertor geometry. Experiment research in ADITYA-U has made significant progress, since last FEC 2016. After installation of PFC and standard tokamak diagnostics, the Phase-I plasma operations were conducted from December 2016 with graphite toroidal belt limiter. Purely Ohmic discharges in circular plasmas supported by Filament pre-ionization was obtained. The plasma parameters, Ip ~ 80-95 kA, duration ~ 80-180 ms with toroidal field (max.) ~ 1T and chord-averaged electron density ~ 2.5 x 10^19 m^-3 has been achieved. Being a medium sized tokamak, runaway electron (RE) generation, transport and mitigation experiments have always been one of the prime focus of ADITYA-U. MHD activities and density enhancement with H2 gas puffing studied. The Phase-I operation was completed in March 2017. The Phase-II operation preparation in ADITYA-U includes calibration of magnetic diagnostics followed by commissioning of major diagnostics and installation of baking system. After repeated cycles of baking the vacuum vessel up to ~ 130°C, the Phase-II operations resumed from February 2018 and are continuing to achieve plasma parameters close to the design parameters of circular limiter plasmas using real time plasma position control. Hydrogen gas breakdown was observed in more than ~2000 discharge including Phase-I and Phase-II operation without a single failure. Several experiments, including the primary RE control with lower E/P operation and secondary RE control with fuelling of Supersonic Molecular Beam Injection as well as sonic H2 gas puffing during current flat-top and Neon gas puffing for better plasma confinement are undergoing. The dismantling of ADITYA and reassembling of ADITYA-U along with experimental results of Phase-I and Phase-II operations from ADITYA-U will be discussed.

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Section: Introductionmentioning

confidence: 99%

Overview of operation and experiments in the ADITYA-U tokamak

et al. 2019

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“…The MHD amplitude increases coherently with the current profile shrinking by radiation (as discussed later in the paper) and leads in most cases to the plasma disruption as shown in the figure 1. Electron density profile peaking is also observed following the Neon injection [17]. As a consequence these plasmas have a relatively slowly evolving character driven by the impurity dynamics on which the effects of the ECRH with a shorter time constant is added.…”

Section: Experiments For Control Of Impurity-triggered Instabilitiesmentioning

confidence: 94%

Experiments on magneto-hydrodynamics instabilities with ECH/ECCD in FTU using a minimal real-time control system

et al. 2015

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Experiments on real time control of magneto-hydrodynamic (MHD) instabilities using injection of electron cyclotron waves (ECW) are being performed with a control system based on only three real time key items: an equilibrium estimator based on a statistical regression, a MHD instability marker (SVDH) using a three-dimensional array of pick-up coils and a fast ECW launcher able to poloidally steer the EC absorption volume with dρ/dt = 0.1/30 ms maximum radial speed. The MHD instability, usually a tearing mode with poloidal mode number m and toroidal mode number n such that m/n = 2/1 or 3/2 is deliberately induced either by neon gas injection or by a density ramp hitting the density limit. No diagnostics providing the radial localization of the instabilities have been used. The sensitivity of the used MHD marker allows to close the control loop solely on the effect of the actuator's action with little elaboration. The nature of the instability triggering mechanism in these plasma prevents that the stabilization lasts longer than the ECW pulse. However when the ECW power is switched on, the instability amplitude shows a marked sensitivity to the position of the absorption volume with an increase or decrease of its growth rate. Moreover the suppression of the dominant mode by ECRH performed at high plasma density even at relatively low power level facilitates the development of a secondary mode. This minimized set of control tools aim to explore some of the difficulties which can be expected in a fusion reactor where reduced diagnostic capabilities and reduced actuator flexibility can be expected.

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“…Finally, we cannot fail to mention the numerous studies on plasmas injected with impurities [32][33][34][35], because it is crucial to determine the conditions that favor a strong increase of particle confinement while minimizing the amount of impurities needed, as well as to favor the so-called "plasma detachment". An increase of the electron density with a remarkable values of the peaking factor are reached in FTU doped pulses.…”

Section: Particle Transport: Collisionality Heating and Doping Effect...mentioning

confidence: 99%

Review of SIRIO interferometer experimental results

Mazzotta

2023

J. Inst.

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The SIRIO (Scanning InfraRed Interferometer) interferometer [1], recently disassembled together with the FTU (Frascati Tokamak Upgrade) experiment [2], worked continuously from 2004 to 2019. An extremely important contribution was made in all the experiments conducted on this tokamak. By virtue of its characteristics, in terms of spatial (1 cm) and temporal resolution (density profiles every 62 μs), combined with its capability to scan the entire plasma column. This interferometer produced all the density feedbacks for operations. Above all, it collected accurate density measurements in plasma physics, among the best data of all tokamak interferometers. In this review, it is reported the highly valuable experimental work of this powerful diagnostics. Indeed, high density observations were analyzed, as well as fast variations were measured; some examples: the detection of plasma instabilities (MARFE), the trace and the speed of the pellets, the measurement of the particle transport efficiencies in important transients etc. In order to improve the knowledge for future interferometry in plasma density measurements projects, some topics related to data analysis are also exposed, as well as local density reconstruction methods.

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Peaked density profiles due to neon injection on FTU

Cited by 16 publications

References 19 publications

Overview of operation and experiments in the ADITYA-U tokamak

Overview of operation and experiments in the ADITYA-U tokamak

Experiments on magneto-hydrodynamics instabilities with ECH/ECCD in FTU using a minimal real-time control system

Review of SIRIO interferometer experimental results

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