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A short probe-forming system is developed for the Columbia Microprobe that includes four electrostatic quadrupoles with a Russian quadruplet configuration. The smallest beam spot size and appropriate optimal parameters of the probe-forming systems have been found. These parameters of the system are compared with appropriate parameters of other field configurations including the electrostatic and magnetic fields with dipole, quadrupole, and rotational symmetry. The new original construction of the electrostatic quadruplet has been manufactured. The sensitivity of this quadruplet to some misalignments of the construction is investigated.

A design is given of a laser ion source for the 4.2 MV Van de Graaff accelerator at the Columbia University Radiological Research Accelerator Facility (RARAF). The source has been designed with application in mind for the RARAF single-particle single-cell microbeam, though it will also be used for broad-beam irradiations. The operating principle, laser ablation, can produce heavy ions with high charge states so that their energies will be high enough to provide sufficient range—at least 20 μm—for irradiating cells on a thin surface at atmospheric pressure. The laser ion source being implemented at RARAF is based on the laser operated ion source used by Hughes at the University of Arkansas and consists of three main components: laser generator, source vacuum chamber, and spherical electrostatic analyzer.