Is it possible to ionise matter on big distance from spaceship to reflect it by magnetic field? The ship can create a big magnetic field to reflect or catch the ionised particles round it. But non-ionised particles will not interact with this field and still be dangerous for ship passengers.
It is possible to ionise that matter to reflect it too? Will this magnetic field be dangerous for the spaceship passengers?
 A: Yes. If you are in a spaceship with a large Lorentz $\gamma$ with respect to the local hydrogen gas (protons + neutral H + neutral H2 molecules) of number density $N$, then the flux of these particles hitting the front of your ship will be $\gamma N c$ [number/ m^2 sec] because the column of particles in front of your ship is Lorentz contracted in your spaceship frame.  For sufficiently large $\gamma$ this can be dangerous radiation for the ship's occupants and also a drag force on the ship.
As you suggest you solve this problem by placing a magnet far in front of the ship at the end of a long stick connected to the ship.  The magnet should be a "septum magnet" which is a sheet of copper carrying a current in the ship's direction of travel.  This produces an up B field to the left of the sheet and a down B field to the right of the sheet. The relativistic charged particles will be deflected to the left and right of the ship by this magnet. Unfortunately, some of the hydrogen is neutral and won't be deflected.  You solve this by placing a thin sheet of material in front of the septum magnet.  In passing thru this sheet, the neutral particles become ionized and thus deflectable by the magnet .... which is the answer to your question.
The septum magnet is far in front of the ship.  The ship's occupants are not in the field.
A: If the ionization will result in unpaired electrons in the atom these atoms will become magnetic. However, since free magnets always attract your "magnetic shield" around the ship will most probably attract and not repel the particles. Of course this is for dielectric, non electrical conductive space-debris or dust particles. If the space particles were to be electrically conductive then the situation changes due to the Lorenz force. Also expect some electrostatic interaction between the ionized space particles and the spaceship.
In general the magnetic shield and ionization of particles idea in practical terms is not such a good idea because the variation in the space particles properties.
A better practice would be to keep the spaceship as possible neutral electromagnetically and don't poke the space particles which mostly of them are in a neutral charge state.
