Fast neutral lithium beam for density and its fluctuation measurements at the boundary regions of ETE tokamak

Oliveira, R. M.; Ueda, M.; Vilela, Waldeir Amaral

doi:10.1590/s0103-97332002000100014

Cited by 4 publications

(2 citation statements)

References 7 publications

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“…In this radial position, the temperature measured by Thomson Scattering diagnostics remained always below 30eV [18]. The principle of density determination used for this situation was based on the comparison of the photon flux profiles emitted from the lithium atoms due to interaction with plasma electrons N vp and due to the interaction with hydrogen gas N vg under same discharge conditions [19]. Here, the electron density is deduced from the relation described in equation 2 [6].…”

Section: Measurements At the Plasmamentioning

confidence: 98%

First results on the fast neutral lithium beam diagnostics probing the edge plasma of the ETE tokamak

Oliveira¹,

Ueda²,

Berni³

2004

Braz. J. Phys.

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One of the main objectives of the research program at ETE is devoted to the study of confinement properties in a low aspect ratio tokamak plasma configuration, and to attain this purpose the determination of plasma parameters of the edge region plays an essential role. A Fast Neutral Lithium Beam (FNLB) diagnostics was developed to perform the measurement of the density profile and its fluctuations at the edge of the plasma in ETE. The first light signals were collected after the filling of ETE chamber with He gas (10 −4 Torr), where the optimization of this diagnostics was done, to adjust the better point for focalization of the beam and for the optical detection system setup. An extensive study of the variation of the intensity of the light signal with the variation of the gas pressure was carried out. This calibration will be used during shots in ETE to measure the rapidly varying pressure of the pulsed discharge by FNLB technique, a requirement imposed by the use of puff valves for injection of the gas. This paper will also describe the several phases of the development of this diagnostics, discuss the problems occurred and the adopted solutions and show the first measurements of the probing of the edge plasma of ETE with FNLB.

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Section: Measurements At the Plasmamentioning

confidence: 98%

First results on the fast neutral lithium beam diagnostics probing the edge plasma of the ETE tokamak

Oliveira¹,

Ueda²,

Berni³

2004

Braz. J. Phys.

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“…For this initial phase a set of electromagnetic and optical diagnostics are already installed. For edge plasma investigation a 10 keV Fast Neutral Lithium Beam (FNLB) is under development with glassy β-eucryptite source that will furnish beam currents up to 1 mA/cm 2 [3]. To measure the electron temperature and density profiles a one-channel Thomson scattering (TS) system was implemented.…”

Section: The Ete Spherical Tokamakmentioning

confidence: 99%

Thomson scattering diagnostic on the ETE tokamak: status and progress

Berni¹,

Bosco²,

Oliveira³

et al. 2004

Braz. J. Phys.

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In order to measure the plasma temperature and density in the spherical tokamak ETE, a one-channel Thomson scattering system was implemented. During the upgrade of capacitor banks and optimization since the beginning of operation, the plasma pulse duration has increased from 1.5 ms up to 12 ms with plasma currents varying from 10 kA to 60 kA. During this phase, the electron temperature was increased from 20 eV to 160 eV with densities as high as 3.5×1019 m −3 . Presently, the Thomson scattering diagnostic is being upgraded based on the time-delay technique, that consists in using fibers of different lengths to transmit the scattered light signals to the same polychromator. This system will allow measurements of electron temperature and density profiles with ten spatial points per laser shot and per polychromator. This work describes in details the Thomson scattering system, presents a selection of results obtained by this system since the initial phase of operation, and shows details of the proposed upgrade of the Thomson scattering system. The ETE Spherical TokamakThe ETE (Experimento Tokamak Esférico) is a medium-size spherical torus with an aspect ratio of 1.5, major radius of 0.3 m, toroidal field of 0.4 T and plasma current of 0.22 MA for the first stage of operation [1]. The objectives of the project are focused on plasma edge investigation, development of diagnostics and training on tokamak operation. The vacuum vessel was manufactured with Inconel 625 with an external diameter and height of 1.2 m and an internal tube with a diameter of 0.18 m, which houses the ohmic solenoid and the inner legs of the toroidal coils. Good access for diagnostics is provided by 58 Conflat ports (12xCF14", 4xCF250 and 42xCF40). The vacuum system comprises three pumps: one turbo drag pump (1500 l/s) backed by an oilfree diaphragm (4 m 3 /h) and an auxiliary mechanical pump (30 m 3 /h). A base pressure of 7.8×10 −8 Torr was achieved after conditioning the vessel walls with baking (T < 150 o C) and DC glow discharge cleaning (GDC) with helium gas.There are three capacitor banks that storage energy for the toroidal, ohmic heating and equilibrium coils. The energy of the capacitor banks is being increased by adding more capacitors and increasing the maximum voltage rating. Presently, the acquisition system is based on CAMAC and oscilloscopes that, in a near future, will be replaced by VME technology [2]. Table 1 summarizes the status of the proposed diagnostics for ETE. For this initial phase a set of electromagnetic and optical diagnostics are already installed. For edge plasma investigation a 10 keV Fast Neutral Lithium Beam (FNLB) is under development with glassy β-eucryptite source that will furnish beam currents up to 1 mA/cm 2 [3]. To measure the electron temperature and density profiles a one-channel Thomson scattering (TS) system was implemented. Thomson Scattering Diagnostic in ETEThe TS is based on a 10 J Q-switched ruby laser (λ = 694.3 nm, pulse duration: 30 ns) that probes the plasma horizontally at the mid-plane. Th...

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Multipoint Thomson scattering diagnostic for the ETE tokamak

Berni

Alonso

Oliveira

2004

Review of Scientific Instruments

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To measure the electron temperature and plasma density profiles on the Experimento Tokamak Esférico tokamak a multiplexed Thomson scattering diagnostic was implemented. The diagnostic is based on a 10 J ruby laser and a single five spectral channel filter polychromator. A collection lens with f/6.3 relay the scattered light from 23 spatial points to optical fibers. The fibers have a monotonous increasing length and are inserted into the polychromator. Between the collection lens and each fiber optic we have a microlens to match the numerical aperture and to enlarge the plasma observation volume. This work describes the project, the simulations, and the preliminary results obtained with the first four optical fibers.

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Fast neutral lithium beam for density and its fluctuation measurements at the boundary regions of ETE tokamak

Cited by 4 publications

References 7 publications

First results on the fast neutral lithium beam diagnostics probing the edge plasma of the ETE tokamak

First results on the fast neutral lithium beam diagnostics probing the edge plasma of the ETE tokamak

Thomson scattering diagnostic on the ETE tokamak: status and progress

Multipoint Thomson scattering diagnostic for the ETE tokamak

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