Publication

Recent research on plasma heating by the Fusion Group

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The Fusion Group has been working hard to improve our understanding of the deuterium-tritium (D-T) plasmas carried out at JET during late 2021. These experiments broke the world fusion energy record and are providing us with invaluable physical insight in preparation of ITER’s experiments.

Our research has culminated in two recent papers published at Plasma Physics and Controlled Fusion. One tackles the optimization of the H and 3He minority heating schemes for D-T, while the other describes a recent upgrade we developed for the calculation of the diffusion operator. A brief overview is given together with their links to the journal version as follows.

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Evolution and validation of neutron simulations with NEUTRO – Article in Plasma Physics and Controlled Fusion

Building on the work described in our previous posts (please see links below), we have continued developing NEUTRO, the neutronics module in Alya. The latest advancements are portrayed in the article entitled “Validating NEUTRO, a deterministic finite element neutron transport solver for fusion applications, with literature tests, experimental benchmarks and other neutronic codes” that has been recently published in Plasma Physics and Controlled Fusion (PPCF).

Neutron damage to fusion reactor materials and tritium self-sufficiency are two significant challenges that need to be solved for fusion to be a viable energy source integrated with the electricity grid. The development of future fusion reactors requires a thorough understanding and the ability to predict these processes, which in turn means highly demanding simulations need to be performed to assist in the analysis of the consequences of neutrons interacting with the vast array of reactor components.

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Disentangling the electronic structure of tungsten metal

Projected Density of States (PDOS) spectra of bcc tungsten structure with 3456 atoms calculated using Linear-Scaling BigDFT, compared to hard x-ray photoelectron spectroscopy (HAXPES) valence band spectra. Image adapted from arXiv:2109.04761v1

Tungsten is one of the reference plasma-facing materials in fusion power devices due to its excellent temperature resistance and low tritium retention. The investigation of the electronic structure is key for implementing tungsten-based technologies as it is strongly related to the stability and properties of the material. However, despite the large efforts in studying the electronic properties of tungsten metal, some complex features are still not properly characterised.

The combination of state-of-the-art experimental and theoretical approaches is key to describing the electronic structure of tungsten, as presented in a recent publication in Physical Review B, entitled “Lifetime effects and satellites in the photoelectron spectrum of tungsten metal“.

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Our newest contribution to the journal of Fusion Engineering and Design

The final goal of fusion power plants is to produce electricity in the grid. This is planned to be done by heating up water as with fission power plants or thermal power stations. In the case of magnetically confined fusion, neutrons released from the hot fusion plasma escape the magnetic confinement and finish in the wall heating up water. In the case of DEMO (DEMOnstration power plant), the neutron production will be large and the reactor materials have to be neutron-resistant. Thereby, neutronics becomes an increasingly important field of study.

Our recent paper published in the journal of Fusion and Engineering Design entitled “Validations of the radiation transport module NEUTRO: a deterministic solver for the neutron transport equation“ reports on our on-going efforts in this field, carried out in collaboration with the CNEA-CONICET in Buenos Aires (Argentina). It can be accessed for free via this link during the first 50 days after the publication.

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Our recent collaboration selected as featured paper in Physics of Plasmas

Since the theoretical description of the three-ion scheme back in 2015 [1], the scheme has been tested and proven in several fusion devices such as Alcator C-Mod, JET and AUG. The main idea underlying this radiofrequency (RF) scheme comes from the polarization of the wave. In essence, what is sought, is the maximization of the electric field component that rotates as the ions do around the magnetic field. This condition is typically reached when the resonance location of the minority ion species coincides with the so-called L-cutoff of the wave. The result? A highly dominant ion absorption of the wave and a very energetic ion distribution.

We are very happy to announce that the recently published paper “Physics and applications of three-ion ICRF scenarios for fusion research” has been selected as a featured paper in the prestigious Physics of Plasmas journal, where two members of our group, Mervi Mantsinen and Dani Gallart, have collaborated. The paper presents many of the advances on this scheme during these last years, especially from the experimental point of view and the developed theoretical framework.

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Our recent papers published in open-access RF Topical Conference Proceedings

The RF Topical Conference is held every two years by a different host. Last year it took place at Hefei, China. From our Fusion Group Dr Dani Gallart had the chance to participate to the event; you can read more about his experience in this earlier post.

The RF Topical Conference tackles several radio-frequency topics in plasmas such as: experiments, modelling, interactions of wave and plasma edge and other related subjects. Recently, the conference contributions from the 2019 edition have been  published in the AIP Conference Proceedings and are in open-access. The Fusion Group has contributed to a total of 6 papers which are briefly described in the following:

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