Experimental Demonstration of Nondisruptive, Central Fueling of a Tokamak by Compact Toroid Injection

Raman, R.; Martín, F.; Quirion, B.; St-Onge, M.; Lachambre, J. L.; Michaud, Daniel; Sawatzky, B.; Thomas, John C.; Hirose, Akira; Hwang, D. Q.; Richard, Nicolas; Côté, C.; Abel, G.; Pinsonneault, D.; Gauvreau, J. L.; Stansfield, B.L.; Decoste, R.; Cote, A.; Zuzak, W.; Boucher, C.

doi:10.1103/physrevlett.73.3101

Cited by 95 publications

(44 citation statements)

References 12 publications

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“…Injection of a CT occurs on a time-scale of several microseconds, followed by a period of disintegration, which should require less than 100 ms, applying either of the two disassembly mechanisms proposed by Parks [2]. Rapid (<0.5 ms) density increase accompanied by a similarly fast soft X ray drop, upon CT injection, was reported by Raman et al, in an experiment with similar CT and tokamak parameters [6]. The several millisecond risetime in tokamak density measured in this experiment is much longer than can be accounted for by CT decay, and suggests that CTs have not fully penetrated into the tokamak plasma.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

“…To date, there have been several experimental investigations of CT injection into tokamaks. Initial experimental demonstrations of injection of an unaccelerated CT into a small tokamak [5] have been followed by non-disruptive injection of CTs into the medium sized TdeV tokamak [6].…”

Section: Introductionmentioning

confidence: 99%

Effects of CT injector acceleration electrode configuration on tokamak penetration

Yee

Bellan

1998

Nucl. Fusion

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“…The compact toroid injector, a coaxial plasma accelerator, shown in Figure 1.5, has the potential to efficiently fuel a tokamak by injecting plasma directly into the reactor center [12,14,15] and is showing promise. Active research has been carried out in Canada, both at the University of Saskatchewan [16,17] and at the former Tokamak de Varrennes (TdeV) [18,19] as well as at UC Davis [20,21], and the University of Hyogo [22,23].…”

Section: Nuclear Fusion and The Tokamak Reactormentioning

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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“…"CT Neutralization Fuel Injection" is an expansion of the "CT Injection" method [1,2]. The "CT Injection" method was proposed as a fuel-injection method for largescale power generation plasmas such as the ITER.…”

Section: Introductionmentioning

confidence: 99%

Computation of Neutral Gas Flow Generation From a CT Neutralization Fuel-Injector

Watanabe

Ohshima

Takahashi

et al. 2012

Plasma and Fusion Research

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The feasibility of compact torus (CT) neutralization fuel injection method is studied by a simulation model using particle and MHD hybrid techniques. The neutralization process is simulated by using rate-coefficients. The magnetic and electric fields are found to respond sluggishly to the neutralization process. Slow ions generated by charge-exchange have been added to the model, although the CT neutralization process was not significantly affected by this. Finally, the minimum length for the CT neutralizer is proposed as 2 m from the simulation run time 10 µs at a CT injection speed of 200 km/s.

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Experimental Demonstration of Nondisruptive, Central Fueling of a Tokamak by Compact Toroid Injection

Cited by 95 publications

References 12 publications

Effects of CT injector acceleration electrode configuration on tokamak penetration

Effects of CT injector acceleration electrode configuration on tokamak penetration

Repetitive operation of the University of Saskatchewan Compact Torus Injector

Computation of Neutral Gas Flow Generation From a CT Neutralization Fuel-Injector

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