Patent ID: 7498588

Claim:
A method of producing an ion beam in a tandem accelerator, the method comprising the acts of: insulating, in a cavity containing an insulating gas under pressure, a beam tube having first and second ends and a terminal situated between the first and second ends; sealing, using a load lock valve, the insulating gas under pressure; generating an operating voltage using a first voltage source situated outside the cavity when the operating voltage is to be less than or equal to a threshold value; generating the operating voltage using a second voltage source situated inside the cavity when the operating voltage is to be greater than the threshold value; coupling the terminal to the first or second voltage sources, the coupling including inserting a voltage injector through the load lock valve for coupling the terminal to the first voltage source when the operating voltage is to be less than or equal to the threshold value and decoupling and withdrawing the voltage injector from the load lock valve when the operating voltage is to be greater than the threshold value; generating, using a particle source, an ion beam; receiving the ion beam at the first end of the beam tube; accelerating the ion beam in a first part of the beam tube that is situated between the first end of the beam tube and the terminal; changing a polarity of the charge of the ion beam; and accelerating the ion beam in a second part of the beam tube which is situated between the terminal and the second end of the beam tube.