Isotope identity experiments in JET with ITER-likewall

Dimensionless experiments test the invariance of plasma physics to changes in the dimensional plasma parameters, when the canonical dimensionless parameters, such as rho_star, nu_star, beta, q, … are conserved [1], [2]. In particular, isotope identity experiments exploit the change in isotope ion mass A = mi/mp to obtain plasmas with identical dimensionless profiles in the same tokamak. In order to keep rho_star, nu_star, beta and q fixed when also varying A, the plasma current, toroidal magnetic field and the density and temperature must scale, respectively, as I_P, B_T ~ A^(3/4), n ~ A and T ~ ?A [3]. However, conditions at the plasma boundary, such as influx of neutral particles, may introduce additional physics, potentially invalidating this approach. Moreover, although the isotope mass appears explicitly only in the parameter rho_star_i, changing A in experiment will affect all plasma kinetic profiles, both in the core and edge plasma, therefore achieving an isotope identity is not trivially expected a priori.