We have performed real-time soft error rate (RT-SER) measurements on bulk 65-nm static random access memories (SRAMs) during deuterium–deuterium (D-D) plasma operation at W–tungsten–Environment in ...Steady-state Tokamak (WEST). The present measurement campaign was characterized by the production of several tens of long pulse discharges (∼60 s) and by a total neutron fluence (at the level of the circuits under test) up to ∼10 9 n·cm−2, improving the error statistics by a factor of more than 6 with respect to the first measurements obtained in 2020. The experimental results demonstrate the occurrence of bursts of single-event upsets (SEUs) during the most efficient shots and 12% of multiple cell upset (MCU) events. Time-resolved data also show that MCUs are preferentially detected in the last part of these long pulses, providing further evidence that higher energy neutrons, initiated by deuterium–tritium (D-T) reactions due to triton burn-up in the D-D plasma, may play a role in the production of MCUs that cannot be attributed in such large proportions to “low-energy” neutrons produced in D-D reactions.
Several designs of magnetrons are discussed in the literature, which are mainly for industrial heating applications. Exotic applications such as current drive systems for plasmas, seeker systems, and ...accelerator systems may have power and frequency requirements, which are usually not met in the ISM band. This article presents the design of a 3.7-GHz 8-kW continuous wave (CW) magnetron, which can be used as a potential source for the lower hybrid current drive (LHCD) system of a tokamak. The simulation results predict a CW output power of about 8 kW with a 62% efficiency. Furthermore, a novel design of a 16-kW CW stacked magnetron is also presented with a simulated efficiency of 63%.
In this study, a novel approach has been investigated by using a mixture of thorium and molten salts as a dual-purpose coolant and medium for the production of fissile fuel in a Fusion Fission Hybrid ...Reactor (FFHR) for the reference geometry of ITER. The study highlighted the broader benefits of thorium fuel cycling, safety features, and reduced radioactive minor actinides generation. The use of a thorium-melted salt coolant for fissile fuel production in a fusion-fission hybrid reactor represented a promising path towards efficient and sustainable nuclear energy, with potential benefits in terms of safety features and reduced generation of radioactive minor actinides. In this study, SS 316 LN-IG was selected as the first wall material for the reactor, and a molten salt fuel mixture of LiF–ThF4 was used as the coolant, taking into account the eutectic points of the material, the nominal fusion power in the FFHR for the Tokamak design concept is considered to be 500 MW. The nuclear code MCNP6 was used with the nuclear data libraries ENDF/B-VIII and CLAW-IV for the neutron calculations. The time evolution of the isotopes in the reactor was calculated with the interface code MCNPAS. The study results are evaluated in terms of tritium breeding ratio, energy multiplication factor, radiation damage, fissile fuel production and fuel burn-up value.The 4-year operation history of total TBR value is calculated and always above 1.05 and increases with time.Th initially decreased from 631.3 tonnes to 587.2 tonnes, while 233U production during this period was 9.1 tonnes. According to these results, the first wall replacement period was calculated as 3.9 years.
•Considering the blanket parameters of ITER for Novel approach to Fusion Fission Hybrid Reactor (FFHR).•Successfully demonstrating the potential of using a thorium-molten salt coolant for fissile fuel production.•Employing MCNP6 with ENDF/B-VIII and CLAW-IV nuclear data libraries for neutron calculations.•Demonstrating fissile fuel production, accompanied by 233U production of 9.1 tonnes.•Achieving a TBR above 1.05 and evaluating the fuel burn-up value as a key parameter for reactor performance.
The integrated commissioning of the tungsten (W) environment in steady-state tokamak (WEST) was started with the superconducting magnet cool-down and completed one year after by the injection of 2.5 ...MW of additional power. It consisted of several steps: local system commissioning, integrated commissioning without plasma, and first plasma operation. This article reviews these WEST commissioning phases and highlights the experiences and the lessons learned. The magnet cooling down operation was initiated in late September 2016. The vacuum vessel was pumped out three weeks before the first plasma. The impregnation and curing of the two in-vessel divertor coils was performed at 180 °C during two days contributing to the baking of the vacuum vessel. In the meanwhile, rehearsal sessions for testing the CODAC systems were organized every month. The toroidal, poloidal, and divertor field coils were energized and their performance was tested successfully allowing moving to the first plasma operation phase. After a few attempts, plasma breakdown was achieved confirming that all systems were properly running and synchronized. Due to several micro air leaks on fiber optic feedthroughs and issues with the design of the in-vessel stabilizing plates, plasma current ramp-up could not be achieved in a first step. Once these issues have been fixed, confined plasmas could be obtained. Diverted plasmas were then achieved and the plasma current was increased up to 800 kA for more than 10 s. Up to 2.5 MW of additional power was eventually successfully coupled to the plasma.
The canonical profiles transport model (CPTM), whose coefficients were determined from the T‑10 tokamak database with a standard magnetic field
B
T
= 2.3–2.5 T, has shown its robustness in ohmic ...regimes with a reduced magnetic field
B
T
= 1.55–2.1 T. We used the CPTM for predictions of radial profiles and dependences of the electron and ion temperatures and the energy confinement time on the average plasma density for the T-15MD tokamak at the initial stage of its operation: the ohmic regime in a circular limiter configuration with
B
T
= 1.0 – 2.0 T and plasma current
I
p
< 1 MA.
Reinforcement learning (RL) has shown promising results for real-time control systems, including the domain of plasma magnetic control. However, there are still significant drawbacks compared to ...traditional feedback control approaches for magnetic confinement. In this work, we address key drawbacks of the RL method; achieving higher control accuracy for desired plasma properties, reducing the steady-state error, and decreasing the required time to learn new tasks. We build on top of Degrave et al. (2022), and present algorithmic improvements to the agent architecture and training procedure. We present simulation results that show up to 65% improvement in shape accuracy, achieve substantial reduction in the long-term bias of the plasma current, and additionally reduce the training time required to learn new tasks by a factor of 3 or more. We present new experiments using the upgraded RL-based controllers on the TCV tokamak, which validate the simulation results achieved, and point the way towards routinely achieving accurate discharges using the RL approach.
•Develop and expand techniques for creating tokamak magnetic controllers through reinforcement learning.•Improve shape accuracy by up to 65% and reduce steady-state offsets in simulation.•Reduce training time for controller generation by a factor of 3 or more through episode chunking and agent transfer.•Comparison of new controllers with experimental results on the Tokamak à Configuration Variable (TCV).
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