A diagnostic neutral beam system for the MST reversed-field pinch

Abdrashitov, G. F.; Давыденко, В. И.; Deichuli, P. P.; Hartog, D. J. Den; Fiksel, G.; Ivanov, A. A.; Korepanov, S.; Murakhtin, S. V.; Shulzhenko, G. I.

doi:10.1063/1.1318249

Cited by 34 publications

(5 citation statements)

References 11 publications

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“…These data were combined with those from the probes installed in a radial limiter shadow to provide the electron temperature profile. Temporal variation of the ion temperature of the target plasma was measured by Rutherford scattering of a diagnostic neutral beam (DNB) [60][61][62]. At the end of the beam injection pulse, the ion temperature was close to that of the electrons [63].…”

Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

Gas-dynamic trap: an overview of the concept and experimental results

Ivanov

Prikhodko

2013

Plasma Phys. Control. Fusion

134

118

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A gas dynamic trap (GDT) is a version of a magnetic mirror whose characteristic features are a long mirror-to-mirror distance, which exceeds the effective mean free path of ion scattering into a loss cone, a large mirror ratio (R ∼ 100) and axial symmetry. Under these conditions, the plasma confined in a GDT is isotropic and Maxwellian. The rate at which it is lost out of the ends is governed by a set of simple gas-dynamic equations, hence the name of the device. Plasma magnetohydrodynamic stability is achieved through a plasma outflow through the end mirrors into regions, where the magnetic-field lines' curvature is favorable for this stability. A high flux volumetric neutron source based on a GDT is proposed, which benefits from the high β achievable in magnetic mirrors. Axial symmetry also makes the GDT neutron source more maintainable and reliable, and technically simpler. This review discusses the results of a conceptual design of the GDT-based neutron source for fusion materials development and fission-fusion hybrids. The main physics issues related to plasma confinement and heating in a GDT are addressed by the experiments performed with the GDT device in Novosibirsk. The review concludes by updating the experimental results obtained, a discussion about the limiting factors in the current experiments and a brief description of the design of a future experimental device for more comprehensive modeling of the GDT-based neutron source.

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Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

Gas-dynamic trap: an overview of the concept and experimental results

Ivanov

Prikhodko

2013

Plasma Phys. Control. Fusion

134

118

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“…The charge exchange recombination spectroscopy (CHERS) system is used to measure the velocity, temperature, and density of C 6+ ions in HSX. A 30 keV, 4 A, 3 ms diagnostic neutral beam [17] is fired radially through the plasma. The neutral beam does not cause any measurable perturbations to the electron temperature and density profiles.…”

Section: The Chers Systemmentioning

confidence: 99%

Comparison of the flows and radial electric field in the HSX stellarator to neoclassical calculations

Briesemeister

Zhai

Anderson

et al. 2012

Plasma Phys. Control. Fusion

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Intrinsic flow velocities of up to ∼20 km s −1 have been measured using charge exchange recombination spectroscopy (CHERS) in the quasi-helically symmetric HSX stellarator and are compared with the neoclassical values calculated using an updated version (Lore 2010 Measurement and Transport Modeling with Momentum Conservation of an Electron Internal Transport Barrier in HSX (Madison, WI: University of Wisconsin); Lore et al 2010 Phys. Plasmas 17 056101) of the PENTA code (Spong 2005 Phys. Plasmas. 12 056114). PENTA uses the monoenergetic transport coefficients calculated by the drift kinetic equation solver code (Hirshman et al 1986 Phys. Fluids 29 2951; van Rij and Hirshman 1989 Phys. Fluids B 1 563), but corrects for momentum conservation. In the outer half of the plasma good agreement is seen between the measured parallel flow profile and the calculated neoclassical values when momentum correction is included. The flow velocity in HSX is underpredicted by an order of magnitude when this momentum correction is not applied. The parallel flow is calculated to be approximately equal for the majority hydrogen ions and the C 6+ ions used for the CHERS measurements. The pressure gradient of the protons is the primary drive of the calculated parallel flow for a significant portion of the outer half of the plasma. The values of the radial electric field calculated with and without momentum correction were similar, but both were smaller than the measured values in the outer half of the plasma. Differences between the measured and predicted radial electric field are possibly a result of uncertainty in the composition of the ion population and sensitivity of the ion flux calculation to resonances in the radial electric field.

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“…The small signal-to-background ratio expected from the toroidal view motivated an upgrade to the diagnostic neutral beam. 9 An attempt was made to decrease the angular divergence and increase the beam current, both of which should increase the charge exchange signal, S ϳ I b / r b ͑I b is the beam current and r b is the radius of the beam at the measurement location͒. The beam current, I b , was increased by nearly a factor of 2 from ϳ2.5 to ϳ5 A.…”

Section: Diagnostic Neutral Beam Upgradementioning

confidence: 99%

Toroidal charge exchange recombination spectroscopy measurements on MST

Magee

Hartog

Fiksel

et al. 2010

Review of Scientific Instruments

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Charge exchange recombination spectroscopy measurements of the poloidal component of the C(+6) temperature and flow in the Madison Symmetric Torus have been vital in advancing the understanding of the ion dynamics in the reversed field pinch. Recent work has expanded the diagnostic capability to include toroidal measurements. A new toroidal view overcomes a small signal-to-background ratio (5%-15%) to make the first localized measurements of the parallel component of the impurity ion temperature in the core of the reversed field pinch. The measurement is made possible through maximal light collection in the optical design and extensive atomic modeling in the fitting routine. An absolute calibration of the system allowed the effect of Poisson noise in the signal on line fitting to be quantified. The measurement is made by stimulating emission with a recently upgraded 50 keV hydrogen diagnostic neutral beam. Radial localization is ∼4 cm(2), and good temporal resolution (100 μs) is achieved by making simultaneous emission and background measurements with a high-throughput double-grating spectrometer.

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A diagnostic neutral beam system for the MST reversed-field pinch

Cited by 34 publications

References 11 publications

Gas-dynamic trap: an overview of the concept and experimental results

Gas-dynamic trap: an overview of the concept and experimental results

Comparison of the flows and radial electric field in the HSX stellarator to neoclassical calculations

Toroidal charge exchange recombination spectroscopy measurements on MST

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