Negative ion source method and apparatus used in conjunction with a charged particle cancer therapy system

A method for injecting a charged particle beam into an accelerator of an irradiation device, said irradiation device irradiating a tumor during use, said method comprising the steps of:

• generating negative ions in a negative ion source, said negative ion source comprising a magnetic field barrier separating a high energy plasma region from a low temperature plasma zone;
• extracting the negative ions from said negative ion source;
• focusing said negative ions using an ion beam focusing lens;
• and
• converting the negative ions into the charged particle beam with a converting foil.

An apparatus for generating ions, said ions used in an irradiation device for treatment of a tumor during use, said apparatus comprising:

• a negative ion source, said negative ion source comprising:
• a first ion generation electrode at a first end of a high temperature plasma chamber in said negative ion source;
• a second ion generation electrode at a second end of said high temperature plasma chamber;
• means for generating a magnetic field barrier separating said high temperature plasma chamber from a low temperature plasma zone, wherein said magnetic barrier selectively passes elements of plasma in said high temperature plasma chamber to said low temperature plasma zone, wherein low energy electrons interact with atomic hydrogen to create hydrogen anions in said low temperature plasma zone;
• and
• an electrode configured to apply a high voltage pulse across said low temperature plasma zone to extract the hydrogen anions from said negative ion source as a negative ion beam.