Carbon Nanotube Stripping Foil for High Current Tandem Accelerator and Charge Exchange Injection into Storage Rings

A variety of accelerator applications (acceleration of ions in tandem accelerators; flexible extraction of ions from cyclotrons; accumulation of preliminary-accelerated heavy ions, protons, or deuterons in circular accelerators and storage rings) all use charge-exchange beam control to affect the process through the stripping of negative ions. For all these applications, it is necessary to have adequate negative ion sources and stripping targets. Carbon is used for most solid stripping targets because its high mechanical stability at high temperature provides the longest lifetime. The stripping target thickness depends on the application and, for carbon, can range from 300 nanograms/cm2 for stripping in high current tandems to 300 micrograms/cm2 for charge exchange injection at 400 MeV. This project will develop new a method of manufacturing ultra-thin films made of woven and cross-linked carbon nanotubes, which can be used for both charge-exchange injection into cyclotrons and storage rings, and electron stripping in high current tandem accelerators. Phase I will examine how the method can be used to build self supporting structures for use as charge-exchange foils. Phase II will build, characterize, and test foils of appropriate thicknesses and attach them to boundary materials. Tests for lifetime and stability will be made using high current ion beams from with energies from 1 MeV to 400 MeV. Commercial Applications and other Benefits as described by the awardee: In addition to Nuclear Physics applications, the technology should be important to medical science for production of clinical medical isotopes and treatment of cancer with neutrons, to industrial processes such as ion implantation in semiconductors, and to Homeland Security for detection of hidden nuclear materials and explosives.