Monte Carlo estimates of edge particle sources in TJ-II plasmas

López‐Bruna, D.; Popov, Tsv.; Cal, E. de la

doi:10.1088/1742-6596/700/1/012006

Cited by 4 publications

(6 citation statements)

References 8 publications

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“…The FDPT was successfully applied to the probe diagnostic experiments on the CASTOR [4], COMPASS [5,30] and ISSTOK [8] tokamaks, as well as on the TJ-II stellarator [5] where examples are included how the T e is determined. The EEPF obtained using our expressions for ψ ||,⊥ (W, B) in hydrogen and deuterium plasmas in the COMPASS tokamak and the TJ-II stellarator yielded values of the electron temperatures and densities in satisfactory agreement with the Thomson scattering (TS) results, as well as with the calculations by the ASTRA package for the COMPASS tokamak and by the EIRENE code for the TJ-II stellarator [5,32].…”

Section: The Estimation Of the Upper Limitsupporting

confidence: 68%

Plasma properties in the vicinity of the last closed flux surface in hydrogen and helium fusion plasma discharges

Dimitrova,

López-Bruna,

Gunn

et al. 2024

Plasma Phys. Control. Fusion

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The origin of the bi-Maxwellian electron energy distribution function (EEDF) observed in the scrape-off layer (SOL) of tokamak plasmas by means of Langmuir probes is still under discussion. It has been assumed that the ionization of hydrogen and deuterium neutrals by thermal electrons penetrating the SOL from the bulk plasma is the main reason for the appearance of a second Maxwellian. To validate this assumption, radial measurements of the electron temperatures and densities, or the plasma properties in helium plasmas in the GOLEM tokamak and the TJ-II stellarator were performed. The radial profiles of the low-temperature electron group densities follow the trend of the calculated radial profiles of the electron sources arising from the ionization of neutrals in both deuterium and helium plasmas in TJ-II. The difference in the radial location where the bi-Maxwellian EEDF appears can be explained by the difference in the rate coefficients for ionization of deuterium and helium. The results of probe measurements in GOLEM and the WEST tokamak divertor, at one radial location in the SOL, are compatible with the hypothesis concerning the ionization of neutral atoms and the type of the EEDF.

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Section: The Estimation Of the Upper Limitsupporting

confidence: 68%

Plasma properties in the vicinity of the last closed flux surface in hydrogen and helium fusion plasma discharges

Dimitrova,

López-Bruna,

Gunn

et al. 2024

Plasma Phys. Control. Fusion

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“…Usually, even 3D fuelling simulations assume a cloud distribution of neutrals, given by the puffing characteristics [29]. Here, we explore the possible response of neutrals to plasma turbulence, which could modify fuelling properties.…”

Section: Plasma Fuelling Experiments and Neutrals Dynamicsmentioning

confidence: 99%

3D effects on transport and plasma control in the TJ-II stellarator

Castejón¹,

Alegre²,

Alonso³

et al. 2017

Nucl. Fusion

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The effects of 3D geometry are explored in TJ-II from two relevant points of view: neoclassical transport and modification of stability and dispersion relation of waves. Particle fuelling and impurity transport are studied considering the 3D transport properties, paying attention to both neoclassical transport and other possible mechanisms. The effects of the 3D magnetic topology on stability, confinement and Alfvén Eigenmodes properties are also explored, showing the possibility of controlling Alfvén modes by modifying the configuration; the onset of modes similar to geodesic acoustic modes are driven by fast electrons or fast ions; and the weak effect of magnetic well on confinement. Finally, we show innovative power exhaust scenarios using liquid metals.

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“…In addition, this fast increase in plasma density improves the NBI coupling and its heating efficiency. The NBI direct contribution to the particle source approximately doubles after ECRH switch-off, but still remains smaller than the other contributions such as recycling of shine-through (58%) or CX neutrals [25].…”

Section: Nbi Plasmasmentioning

confidence: 89%

“…A necessary input for mode stability analysis is the steady state fast ion pressure profile in both NBI and NBI + ECRH scenarios. Fast ion profiles resulting from the ionization of NBI neutrals and their subsequent slowing-down in the plasma have been calculated using the Monte Carlo code FAFNER [29] with the thermal plasma profiles shown in figures 10 and 12 and the density of neutrals from recycling as obtained from EIRENE [25] for the given discharge conditions (plasma parameters, wall conditioning, puffing and monitored H α light). The precise beam injection geometry is considered in the simulation including scraper losses.…”

Section: Nbi Heating and Fast Ion Pressurementioning

confidence: 99%

Stability analysis of TJ-II stellarator NBI driven Alfvén eigenmodes in ECRH and ECCD experiments

Cappa¹,

Varela

López‐Bruna³

et al. 2021

Nucl. Fusion

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In this paper, we analyze the impact of electron cyclotron resonance heating and electron cyclotron current drive on the Alfvénic instabilities driven by neutral beam injection observed in the TJ-II stellarator. An MHD stability analysis of driven Alfvén eigenmodes compatible with the experimental plasma parameters is carried out in order to compare with the data provided by magnetic coils, radiation monitors, and heavy ion beam probes. To this end, the vacuum magnetic configuration modified by the different levels of plasma current, the thermal plasma parameters and the fast ion pressure profiles generated by the co-injected neutral beam, are entered in the FAR3d gyro-fluid code in order to follow the linear evolution of the destabilized plasma equilibrium. Linear growth rates and radial location of the dominant predicted modes coincident in frequency with the observed fluctuations are presented. Despite the uncertainties related to the estimation of the rotational transform profile, the code predictions agree within reasonable accuracy with the experimental results.

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Monte Carlo estimates of edge particle sources in TJ-II plasmas

Cited by 4 publications

References 8 publications

Plasma properties in the vicinity of the last closed flux surface in hydrogen and helium fusion plasma discharges

Plasma properties in the vicinity of the last closed flux surface in hydrogen and helium fusion plasma discharges

3D effects on transport and plasma control in the TJ-II stellarator

Stability analysis of TJ-II stellarator NBI driven Alfvén eigenmodes in ECRH and ECCD experiments

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