Research Index / High-Field Science / Ion Accelerator

The photo shows the production of accelerated ions by focusing a high-intensity, ultrafast laser beam onto a foil target.

A collimated beam of fast protons, with energies as high as 1.5 MeV and total number of > 109, confined in a cone angle of 40o + 10o is observed when a high-intensity, high-contrast subpicosecond laser pulse is focused onto a thin foil target.  The protons, which originate from impurities on the front side of the target, are accelerated over a region extending into the target and exit out the back side in a direction normal to the target surface.  Acceleration field gradients ~ 10 GeV/cm are inferred.  The maximum proton energy can be explained by the charge-separation electrostatic-field acceleration due to "vacuum heating".

Related article: Closing in on Cancer: A Cheap Proton Source Could Transform Radiotherapy, New Scientist Magazine, Dec. 4, 1999.


Research Index / High-Field Science / Ion Accelerator

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