Ah yes. My difficulty is in understanding how such large potential differences could be maintained in the environment of the solar wind. I would be interested in your explanation.
In a way, they don't. It is what causes comets to be comets as they move through the electrical atmosphere of the sun. Think about it. As a comet moves closer to the sun, the temperature does not rise as much as does the electrical potential. Infact, the coma and tail of a comet form far before the temperature could possibly rise to even the melting point of H2O much less its boiling point, even in a vacuum, if there were water on a comet. Comets start forming these out beyond the orbit of Jupiter and beyond. Temperatures in space out there from the sun range from -128 to -190 C on objects in a vacuum. That is, shall we say, REALLY cold. As Hale-Bopp approached the orbit of Mars, its Coma was larger than the sun, and it grew even larger! How can this be, if it is merely out-gassing steam? It really cannot. It can only be if it is a huge plasma cloud of charge particles, each of which is attempting to get as far from other similarly charged particles as possible as fast as possible. . . and others are being pushed away from the sun by other similarly charged particles: the solar wind! This is the comet trying desperately to equalize its charge with the space around it!
What is another characteristic of any charged plasmas? Look at any neon light. Look at the aurorae borealis and australis. They glow. What do comets and their comas and tails do? They glow with the electrical discharge.
Every comet we have ever visited has been indistinguishable from an Asteroid. They are lumps of rock. The only difference is the electrical charge they carry. For example Halley, Tempel 1, and 67P/Churyumov-Gerasimenko have all shown no signs of H2O at all. These comets have had the appearance of a lump of coal or fresh Macadam. . . reflecting approximately 4% of the light that falls on them, not dirty ice. When the Deep Impact collision occurred, they did find OH radicals and H2O in the ejecta but those were found only in a spew almost 180º back from the point of impact and no where else. The Deep Impact lead scientist Dr. Sunshine was quoted as saying that the water found was "chemically pure, almost as if it had just been created!" The Solar Wind is essentially stripped Hydrogen atoms (Protons and electrons . . . plasmas) which when they encounter Oxygen electron machined from from the comet combine to for OH and H2O, just as the lead Deep Impact scientist said:
"In the Deep Impact data we're essentially watching water molecules form and then dissipate right in front of our eyes," said (Dr. Jessica M.) Sunshine, who said her first reaction to the M3 data was skepticism.
Note that free Hydrogen exists in space and ionized in the Solar wind as both Hydrogen and Deuterium and each can form water with equal alacrity. Add a very, very highly charged plasma field and you will get water signatures from a dry as the Sahara desert asteroid with a highly elliptic orbit which has picked up a HUGE charge that it discharges as it gets closer to the oppositely charged sun. No heat creating steam, but rather electric forces creating very highly charged plasma, the most common form of matter which we see everywhere we look in space.
Note also that some ordinary asteroids have suddenly spouted comas and tails in the solar wind when the sun is very active. Planets like mercury have tails and even some stars have tails as well.