Patent ID: 8791435

Claim:
An apparatus for generating a negative ion beam for use with charged particle radiation therapy, comprising: a negative ion source comprising: a magnetic material; and a high temperature plasma chamber substantially encompassing said magnetic material; wherein said high temperature plasma chamber comprises: a first ion generation electrode at a first end of said high temperature plasma chamber, a second ion generation electrode at a second end of said high temperature plasma chamber, and a magnetic field carrying outer wall; wherein application of a first high voltage pulse across said first ion generation electrode and said second ion generation electrode breaks hydrogen in said high temperature plasma chamber into component parts; wherein said magnetic material yields a magnetic field loop running through said first ion generation electrode, through said magnetic field carrying outer wall, through said second ion generation electrode, across a gap, and through said magnetic material; wherein said magnetic field loop yields a magnetic barrier across said gap between said high temperature plasma chamber and a low temperature plasma region, said magnetic barrier passing a subset of said component parts; wherein low energy electrons interact with atomic hydrogen to create hydrogen anions in said low temperature plasma region; wherein application of a second high voltage pulse across said second ion generation electrode and a third ion generation electrode extracts negative ions from said negative ion source into a negative ion beam.