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computations of the blowout phase itself, and the possibility and limitations of quantitative comparison to experiment. 

## II. THE GYROFLUID MODEL WITH RADIALLY DEPENDENT AXISYMMET- RIC GEOMETRY 

The gyrofluid model used herein is given in Ref. [29]. It is based on the original derivations given in Refs. [33, 34], with corrections given as motivated by free energy conservation. An alternative derivation using the conservation laws of the underlying gyrokinetic model is given in Ref. [35]. The equations are normalised to spatial scale a and time scale a/c$_{s}$ where a is the minor radius and c$_{s}$ is the reference sound speed given by c 2 s = T$_{e}$/M$_{i}$ , that is, in terms of the electron temperature (in energy units) and ion mass. The main parameters are the drift parameter, electron dynamical beta, and electron collisionality, respectively given by 

<img src='content_image/336317.jpg'>

where c and e are the speed of light and fundamental charge, p$_{e}$ and τ$_{e}$ are the pressure and Braginskii collision time [36] of the electrons, and ρ$_{s}$ = c$_{s}$M$_{i}$c/eB is the drift scale. Note that if T$_{i}$ = T$_{e}$ then ρ$_{s}$ = ρ$_{i}$ . The reference for M$_{i}$ is the deuterium mass M$_{D}$ . For the electrons the physical value of the mass m$_{e}$/M$_{D}$ = 1 / 3670 is always used. With global geometry there is no single magnetic field line connection length, but one with a profile with 2 πqR 0 a function of the minor radius coordinate, where R 0 is a constant giving the reference value of the major radius. 

## A. Species constants and gyrofluid moment equations 

Each species z has its own set of gyrofluid moment variable equations, one each for density ˜ n$_{z}$ , parallel velocity ˜ u$_{z}$$_{‖}$ , parallel and perpendicular temperature ˜ T$_{z}$$_{‖}$ and ˜ T$_{z}$$_{⊥}$ , and parallel and perpendicular energy components of the parallel heat flux ˜ q$_{z}$$_{‖}$ and ˜ q$_{z}$$_{⊥}$ . They are coupled to the electrostatic and parallel magnetic potentials ˜ φ and A$_{‖}$ through self consistent field equations. The tilde denotes a dependent variable to distinguish from constant parameters. The correspondence of these equations to the Braginskii fluid model is given in Ref. [30]. Each species is characterised by a background charge density, temperature/charge ratio, and 

