Deep penetration fuelling of reactor-grade tokamak plasmas with accelerated compact toroids

Perkins, L.J.; Ho, Stephanie G Y; Hammer, J.H.

doi:10.1088/0029-5515/28/8/005

Cited by 97 publications

(77 citation statements)

References 16 publications

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“…The conducting sphere (CS) theoretical model was put forth some twenty years ago [8,1,14] and described the injection of a rigid conducting ball into a strongly magnetized background plasma. In the CS model, the Alfvén speed of the background plasma is much higher than the speed of the injected CT, and thus the background field can rearrange itself virtually instantaneously in response to the injected CT.…”

Section: Introductionmentioning

confidence: 99%

A systematical study of neutron-rich Zr isotopes by the projected shell model

et al. 2011

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Abstract. We present results from three-dimensional ideal magnetohydrodynamic simulations of unmagnetized dense plasma jet injection into a uniform hot strongly magnetized plasma, with the aim of providing insight into core fueling of a tokamak with parameters relevant for ITER and NSTX (National Spherical Torus Experiment). Unmagnetized dense plasma jet injection is similar to compact toroid injection but with much higher plasma density and total mass, and consequently lower required injection velocity. Mass deposition of the jet into the background appears to be facilitated via magnetic reconnection along the jet's trailing edge. The penetration depth of the plasma jet into the background plasma is mostly dependent on the jet's initial kinetic energy, and a key requirement for spatially localized mass deposition is for the jet's slowing-down time to be less than the time for the perturbed background magnetic flux to relax due to magnetic reconnection. This work suggests that more accurate treatment of reconnection is needed to fully model this problem. Parameters for unmagnetized dense plasma jet injection are identified for localized core deposition as well as edge localized mode (ELM) pacing applications in ITER and NSTX-relevant regimes.

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Section: Introductionmentioning

confidence: 99%

A systematical study of neutron-rich Zr isotopes by the projected shell model

et al. 2011

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“…According to current theories, one of the key requirements for the success of CT injection schemes is that the plasmoid must attain sufficient kinetic energy density in order to overcome the strong gradient of the tokamak toroidal field (TF) [1]. Owing to the short time-scales involved in the injection process and the high electrical conductivity of the plasma, the tokamak TF must be diamagnetically displaced by the travelling CT.…”

Section: Introductionmentioning

confidence: 99%

Effects of CT injector acceleration electrode configuration on tokamak penetration

Yee

Bellan

1998

Nucl. Fusion

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ABSTRACT. Through compact toroid (CT) injection experiments on the TEXT-U tokamak (with BT 10 kG and IP 100 kA), it has been shown that the acceleration electrode configuration, particularly in the vicinity of the toroidal field (TF) coils of the tokamak, has a strong effect on penetration performance. In initial experiments, premature stopping of CTs within the injector was seen at anomalously low TF strengths. Two modifications were found to greatly improve performance: (a) removal of a section of the inner electrode and (b) increased diameter of the 'drift tube' (which guides the CT into the tokamak after acceleration). It is proposed that the primary drag mechanism slowing CTs is toroidal flux trapping, which occurs when a CT displaces transverse TF trapped within the flux conserving walls of the acceleration electrodes (or drift tube). For a simple two dimensional (2-D) geometry, a magnetostatic analysis produces a CT kinetic energy requirement of 1 2 ρv 2 ≥ α B 2 0 /2µ0 , with α = 2/(1 − a 2 /R 2 ) a dimensionless number that is dependent on the CT radius a normalized by the drift tube radius R. For a typical CT, this can greatly increase the required energies. A numerical analysis in 3-D confirms the analytical result for long CTs (with length L such that L/a > ∼ 10). In addition to flux trapping, the CT shape is also shown to affect the energy criterion. These findings indicate that a realistic assessment of the kinetic energy required for a CT to penetrate a particular tokamak TF must take into account the interaction of the magnetic field with the electrode walls of the injector.

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“…The process of magnetic connection of a CT with a tokamak plasma is demonstrated in Figure 2.4, from Perkins [25].…”

Section: Magnetic Reconnection and Fuel Depositionmentioning

confidence: 99%

Repetitive operation of the University of Saskatchewan Compact Torus Injector

Pant

Hirose

Xiao

2010

Radiation Effects and Defects in Solids

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Development of fueling technologies for modern and future tokamak reactors is essential for their implementation in a commercial energy production setting. Compared to the presently available fueling technologies, gas or cryogenic pellet injection, compact torus injection presents an effective and efficient method for directly fueling the central core of tokamak plasmas. Fueling of the central core of a tokamak plasma is pivotal for providing efficient energy production. The central core plasma of a reactor contains the greatest density of fusion processes. For consistent and continuous fueling of tokamak fusion reactors, compact torus injectors must be operated in a repetitive mode.The goal of this thesis was to study the feasibility of firing the University of Saskatchewan Compact Torus Injector (USCTI) in a repetitive mode. In order to enable USCTI to fire repetitively, modifications were made to its electrical system, control system and data acquisition system. These consisted primarily of the addition of new power supplies, to enable fast charging of the many capacitor banks used to form and accelerate the plasma. The maximum firing rate achieved on USCTI was 0.33 Hz, an increase from the previous maximum firing rate of 0.2 Hz achieved at UC Davis.Firing USCTI in repetitive modes has been successful. It has been shown that the CTs produced in any given repetitive series are properly formed and repeatable. This is made evident through analysis of data collected from the CTs' magnetic fields and densities as they traveled along the injector barrel. The shots from each experiment were compared to the series' mean data and were shown to be consistent over time.Calculations of their correlations show that there are only minimal deviations from shot to shot in any given series.ii

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Deep penetration fuelling of reactor-grade tokamak plasmas with accelerated compact toroids

Cited by 97 publications

References 16 publications

A systematical study of neutron-rich Zr isotopes by the projected shell model

A systematical study of neutron-rich Zr isotopes by the projected shell model

Effects of CT injector acceleration electrode configuration on tokamak penetration

Repetitive operation of the University of Saskatchewan Compact Torus Injector

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