A multi E x B filter system for isotope enrichment application.

The design of a special type E x B (or "Wien") filter for efficient isotope separation is described. Computation results demonstrated that an optimized E x B filter can produce highly enriched isotopes such as 10B, 98Mo, and 100Mo which are useful for the manufacturing of radioactive isotopes for medical diagnostic imaging studies and therapeutic applications. Using the ion beams generated by a large area RF-driven plasma source, it is shown that a multi E x B filter system can greatly enhance the yield of a range of commercially desirable isotopes.

Feasibility study on medical isotope production using a compact neutron generator.

Compact neutron generators can provide high flux of neutrons with energies ranging from thermal (0.025 eV) to 14 MeV. Recent measurements demonstrated high neutron yields from the D-7Li fusion reaction at an interaction energy of 500 keV. Using the D-7Li reaction and applying new advancements in high flux neutron generator technology along with the commercial availability of high voltage DC power supplies enables the production of useful quantities of radioisotopes for medical applications. Using the known neutron reaction cross-sections, it has been estimated that hundreds-to-thousands MBq (or tens-to-hundreds mCi) of 99Mo, 225Ac, 64Cu and 67Cu can be obtained from a compact high flux neutron generator.

Beam-induced back-streaming electron suppression analysis for an accelerator type neutron generator designed for 40Ar/39Ar geochronology.

A facility based on a next-generation, high-flux D-D neutron generator has been commissioned and it is now operational at the University of California, Berkeley. The current generator designed for 40Ar/39Ar dating of geological materials produces nearly monoenergetic 2.45MeV neutrons at outputs of 108n/s. The narrow energy range is advantageous relative to the 235U fission spectrum neutrons due to (i) reduced 39Ar recoil energy, (ii) minimized production of interfering argon isotopes from K, Ca, and Cl, and (iii) reduced total activity for radiological safety and waste generation. Calculations provided show that future conditioning at higher currents and voltages will allow for a neutron output of over 1010n/s, which is a necessary requirement for production of measurable quantities of 39Ar through the reaction 39K(n,p)39Ar. A significant problem encountered with increasing deuteron current was beam-induced electron backstreaming. Two methods of suppressing secondary electrons resulting from the deuterium beam striking the target were tested: the application of static electric and magnetic fields. Computational simulations of both techniques were done using a finite element analysis in COMSOL Multiphysics®. Experimental tests verified these simulations. The most reliable suppression was achieved via the implementation of an electrostatic shroud with a voltage offset of -800V relative to the target.

Development of C(60) plasma ion source for time-of-flight secondary ion mass spectrometry applications.

Initial data from a multicusp ion source developed for buckminsterfullerene (C(60)) cluster ion production are reported in this article. A C(60)(+) beam current of 425 nA and a C(60)(-) beam current of 200 nA are obtainable in continuous mode. Compared to prior work using electron impact ionization, the multicusp ion source provides at least two orders of magnitude increase in the extractable C(60)(+) beam current. Mass spectra for both positive and negative bismuth cluster ions generated by the multicusp ion source are also included.

Ion source for neutral beam injection meant for plasma and magnetic field diagnostics.

At the Lawrence Berkeley National Laboratory a diagnostic neutral beam injection system for measuring plasma parameters, flow velocity, and local magnetic field is being developed. The system is designed to have a 90% proton fraction and small divergence with beam current at 5-6 A and a pulse length of approximately 1 s occurring once every 1-2 min. The ion source needs to generate uniform plasma over a large (8 x 5 cm(2)) extraction area. For this application, we have compared rf driven multicusp ion sources operating with either an external or an internal antenna in similar ion source geometry. The ion beam will be made of an array of six sheet-shaped beamlets. The design is optimized using computer simulation programs.

Application of deuteron-deuteron (D-D) fusion neutrons to 40Ar/39Ar geochronology.

Neutron irradiation of samples for 40Ar/39Ar dating in a 235U fission reactor requires error-producing corrections for the argon isotopes created from Ca, K, and, to a lesser extent, Cl. The fission spectrum includes neutrons with energies above 2-3 MeV, which are not optimal for the 39K(n,p)39Ar reaction. These higher-energy neutrons are responsible for the largest recoil displacements, which may introduce age artifacts in the case of fine-grained samples. Both interference corrections and recoil displacements would be significantly reduced by irradiation with 2.45 MeV neutrons, which are produced by the deuteron-deuteron (D-D) fusion reaction 2H(d,n)3He. A new generation of D-D reactors should yield sufficiently high neutron fluxes (>10(12) n cm(-2)s(-1)) to be useful for 40Ar/39Ar dating. Modeling indicates that irradiation with D-D neutrons would result in scientific benefits of improved accuracy and broader applicability to fine-grained materials. In addition, radiological safety would be improved, while both maintenance and operational costs would be reduced. Thus, development of high-flux D-D fusion reactors is a worthy goal for 40Ar/39Ar geochronology.