A TIEMF model and some implications for ITER magnetic diagnostics

Vila, R.; Hodgson, E.R.

doi:10.1016/j.fusengdes.2009.01.025

Cited by 9 publications

(9 citation statements)

References 10 publications

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“…Considerable clarification of the effects and mechanisms involved has been achieved, however the number of factors identified has markedly complicated the issue [2, and references therein]. Recent work [19] has successfully modelled TIEMF ( fig. 6), while irradiations ( [6] and Fig.…”

Section: Vessel Wiringmentioning

confidence: 99%

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Nuclear technology aspects of ITER vessel-mounted diagnostics

Vayakis

Bertalot

Encheva

et al. 2011

Journal of Nuclear Materials

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ITER has diagnostics with machine protection, basic and advanced control, and physics roles. Several are distributed on the inner and outer periphery of the vacuum vessel. They have reduced maintainability compared to diagnostics in ports. They also endure some of the highest nuclear and EM loads of any diagnostic for the longest time. They include:Inductive sensors for time-integrated and raw inductive measurements; Steady-state magnetic sensors to correct drifts of the inductive sensors;Bolometer cameras to provide electromagnetic radiation tomography; Microfission chambers and neutron activation stations to provide fusion power and fluence; MM-wave reflectometry to measure the plasma density profile and the plasma-wall distance and;Wiring to service magnetics, bolometry, and in-vessel instrumentation. This paper summarises the key technological issues these diagnostics arising from the nuclear environment, recent progress and outstanding R&D for each system.

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Section: Vessel Wiringmentioning

confidence: 99%

“…In particular, the temperature, pressure and typical voltages expected must be simulated in the test and the samples taken to a total fast fluence exceeding 10 24 n / m 2 . Fibre optic current sensor May be replaceable [19]. Black: raw data from coil heating.…”

Section: Reflectometry Antennasmentioning

confidence: 99%

Nuclear technology aspects of ITER vessel-mounted diagnostics

Vayakis

Bertalot

Encheva

et al. 2011

Journal of Nuclear Materials

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“…Cables subject to temperature gradients along their length produce a nonzero thermoelectric EMF due to manufacturing imperfections [25], [26]. In addition to this, nucleartransmutation products can lead to a significant thermally induced EMF at the integrator input during the pulses for invessel sensors, causing again a cumulative error in the integrator output baseline [27].…”

Section: E Thermally Induced Emfmentioning

confidence: 99%

The Magnetic Diagnostic Set for ITER

Testa

Toussaint

Chavan

et al. 2010

IEEE Trans. Plasma Sci.

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“…Nuclear fusion reactors based on the tokamak concept require a set of magnetic probes to reconstruct the plasma equilibrium that can measure magnetic field and at the same time are able to withstand harsh conditions of radiation with sufficient temperature stability and accuracy. These sensors are primarily used to infer the plasma current, boundary shape and position and to provide this information to magnetic control, whose function is to keep the hot plasma away from the vacuum vessel walls, using the currents in the poloidal field PF coils as the main actuators [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. So far, tokamaks have used conventional Mirnov coils (also called pick-up coils) to measure magnetic field time variation dB/dt.…”

Section: Introductionmentioning

confidence: 99%

“…However, as reactor conditions are approached, some difficulties arise. Measurement errors arising from radiation-induced thermoelectric effects (RITEs) in the signal transmission cables (which take the form of spurious spikes) lead after time integration to offsets in the magnetic measurements that are difficult to correct, so the lowfrequency spectrum of the magnetic field is not well determined in long pulse steady-state scenarios [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Optimization of out-vessel magnetic diagnostics for plasma boundary reconstruction in tokamaks

Romero¹,

Svensson²

2013

Nucl. Fusion

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Abstract.To improve the low frequency spectrum of magnetic field measurements of future tokamak reactors such as ITER, several steady state magnetic sensor technologies have been considered. For all the studied technologies it is always advantageous to place the sensors outside the vacuum vessel and as far away from the reactor core to minimize radiation damage and temperature effects, but not so far as to compromise the accuracy of the equilibrium reconstruction.We have studied to what extent increasing the distance between out-vessel sensors and plasma can be compensated for sensor accuracy and/or density before the limit imposed by the degeneracy of the problem is reached. The study is particularized for the Swiss TCV tokamak, due to the quality of its magnetic data and its ability to operate with a wide range of plasma shapes and divertor configurations. We have scanned the plasma boundary reconstruction error as function of out-vessel sensor density, accuracy and distance to the plasma. The study is performed for both the transient and steady state phases of the tokamak discharge.We find that, in general, there is a broad region in the parameter space where sensor accuracy, density and proximity to the plasma can be traded for one another to obtain a desired level of accuracy in the reconstructed boundary, up to some limit.Extrapolation of the results to a tokamak reactor suggests that a hybrid configuration with sensors inside and outside the vacuum vessel could be used to obtain a good boundary reconstruction during both the transient and the flat-top of the discharges, if out-vessel magnetic sensors of sufficient density and accuracy can be placed sufficiently far outside the vessel to minimize radiation damage.

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A TIEMF model and some implications for ITER magnetic diagnostics

Cited by 9 publications

References 10 publications

Nuclear technology aspects of ITER vessel-mounted diagnostics

Nuclear technology aspects of ITER vessel-mounted diagnostics

The Magnetic Diagnostic Set for ITER

Optimization of out-vessel magnetic diagnostics for plasma boundary reconstruction in tokamaks

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