Ion acceleration by a double stage accelerating device for laser-induced plasma ions

A new laser ion source configuration was studied and realized in order to generate and accelerate ions of different elements. This ion source consisted of a laser-induced plasma from solid targets where the plume was made to expand before the action of the accelerating field. The accelerating field was reached by the application of two high voltage power supplies of different polarity. Therefore, the ions were made to undergo double acceleration that can imprint a maximum ion energy up to 160keV per charge state. We analyzed the extracted charge from a Cu target as a function of the accelerating voltage at the laser fluences of 1.7 and 2.3J/cm2. At 60kV of total accelerating voltage and higher laser fluence, the maximum ion dose was 1012ions/cm2. Under this last condition, the maximum output current was 5mA and the emittance measured by the pepper pot method resulted in 0.22 mmmrad. With this machine, biomedical materials such as polyethylene were implanted with carbon and titanium ions. At doses of 6x1015ions/cm2, the polyethylene surface increased its micro-hardness by about 3-fold, as measured by the scratch test.