The positive charge exists at the surface not all through the interior.
"This plot [... http://www.electric-cosmos.org/sun.htm
] is easily measured for a laboratory plasma contained in a column - a cylindrical glass tube with the anode at one end and the cathode at the other. These two terminals are connected into an electrical circuit whereby the current through the tube can be controlled. In such an experiment, the plasma has a constant cross-sectional area from one end of the tube to the other. The vertical axis of the plot in figure 4 is the voltage rise from the cathode up to the anode (across the entire plasma) as a function of the current passing through the plasma. The horizontal axis shows the Current Density. Current density is the measurement of how many Amps per square meter are flowing through a cross-section of the tube. In a cylindrical tube the cross-section is the same size at all points along the tube and so, the current density at every cross-section is just proportional to the total current passing through the plasma.
When we consider the Sun, however, a spherical geometry exists - with the sun at the center. The cross-section becomes an imaginary sphere. Assume a constant total electron drift moving from all directions toward the Sun and a constant total radial flow of +ions outward. Imagine a spherical surface of large radius through which this total current passes. As we approach the Sun from deep space, this spherical surface has an ever decreasing area. Therefore, for a fixed total current, the current density (A/m^2) increases as we move inward toward the Sun.
In deep space the current density there is extremely low even though the total current may be huge; we are in the dark current region; there are no glowing gases, nothing to tell us we are in a plasma discharge - except possibly some radio frequency emissions.
As we get closer to the Sun, the spherical boundary has a smaller surface area; the current density increases; we enter the normal glow region; this is what we call the Sun's "corona". The intensity of the radiated light is much like a neon sign.
As we approach still closer to the Sun, the spherical boundary gets to be only slightly larger than the Sun itself; the current density becomes extremely large; we enter the arc region of the discharge. This is the anode tuft. This is the photosphere. The intensity of the radiated light is much like an arc welding machine or continuous lightning. A high intensity ultraviolet light is emitted.
Some early plasma researchers and most modern astronomers believe that the only "true" plasma is one that is perfectly conductive (and so will "freeze" magnetic fields into itself). Figure 4 indicates that this does not happen. Every point on the plot (except the origin) has a non-zero voltage coordinate. The static resistivity of a plasma operating at any point in figure 4 is proportional to the slope of a straight line drawn from the origin to the point. This means that, at every possible mode in which a plasma can operate, it has a non-zero static resistivity; it takes a non-zero E-field to produce the current density. Obviously the static resistivity of a plasma in the high end of the dark mode can be quite large. (The arc region and the left half of the glow region exhibit negative dynamic resistance - and the E-field can be quite small - but that is not what is in question.) No real plasma can "freeze-in" a magnetic field. The highest conductivity plasmas are those in the arc mode. But, even in that mode, it takes a finite, non-zero valued electric field to produce a current density. No plasma is an "ideal conductor".