Complex sentence: The plasma in a ion laser, unlike a Helium Neon Laser, has a slightly positive resistance, but will still run away without ballasting, this is why ion laser supplies are very difficult to design.
Split into simpler sentences: The plasma in an ion laser, unlike a Helium Neon Laser, has a slightly positive resistance, but will still run away without ballasting. This is why ion laser supplies are very difficult to design.