Figure 2

Analysis diagram of nonextensive geodesic acoustic mode law. (a) The theory of nonextensive geodesic acoustic mode shows that: the frequency of geodesic acoustic mode is directly proportional to ion sound velocity, but the proportional coefficient depends on the safety factor and ion nonextensive parameters. At the extensive limit, the relevant conclusions return to the results under the Boltzmann–Gibbs statistical framework. (b) The analysis of 58 experimental data points of 6 major devices also supports the conclusion that the geodesic acoustic mode frequency is proportional to the ion sound velocity. (c) The variation curve of S in the geodesic acoustic mode scaling law with the safety factor q shows that the geodesic acoustic mode frequency decreases as the safety factor q increases when the ion sound velocity \({{c}_{\mathrm{s}}}\) and the large radius \({{R}_{0}}\) are constant. (d) The variation curve of S in the geodesic acoustic mode scaling law with the ion nonextensive parameter \({ {q}_{{ { F}_{\mathrm{i}}}}}\) indicates that as the ion nonextensive parameter decreases, the geodesic acoustic mode frequency gradually increases (for details see the information of figure given in the “Methods”).