A magnetic source and condenser for creating magnetic flux within a ferrous pipe (P) comprises a rectangular magnet (M) having a pair of opposing major faces and a pair of pole pieces (N and S) sandwiching the magnet. The pole pieces each have a foot (Nf and Sf) extending under the magnet and adjacent the pipe. By virtue of the pole pieces and the feet, the magnetic flux from the magnet is condensed before it is applied to the pipe. Thus it is strong enough to exceed the flux-carrying capacity of the pipe so that it travels away from the pipe in an arc (G) inside the pipe where it cuts perpendicularly the fluid flow (F) within the pipe. The flowing fluid cutting the perpendicular lines of magnetic flux generate electrical currents and charges in the fluid, which in turn ionizes the fluid and dissolved and suspended solids in the fluid, and charges the pipe negative to protect the pipe from scale, corrosion, algae, parafinning, etc. A plurality of magnets and condenser units (D) are also mounted on the inside of a circular nonmagnetic enclosure (E) in a circumferentially spaced direction and outside an interior pipe (P) which is coaxial with the enclosure.