Compact Ion Cyclotron for Nuclear Security Application (Phase 1 Final Report FY 2019 Release 2)
- RadiaBeam Technologies, LLC, Santa Monica, CA (United States)
The mission of the Office of Defense Nuclear Nonproliferation Research and Development Division at DOE is to develop effective systems for nuclear security. Special nuclear material (SNM) detection can be performed by either passive or active interrogation. Passive detection looks for the 186 keV gamma decay line in 235U and the 2.60 MeV line in the 208Tl impurity. This is very difficult in practice because both signatures are easily shielded or are otherwise indiscernible from background. This proposal focuses on active, accelerator-based interrogation systems. Commercially-available accelerator-based security inspection systems generally exploit the broad bremsstrahlung spectrum generated using a 6-10 MeV, pulsed, low-duty cycle electron accelerator (i.e. linac or betatron) which in the presence of significant backgrounds presents difficulties in image and material identification making precise analysis challenging. An alternative approach is to use ions, which can excite nuclear states either directly, or through generation of secondary high-energy signature gammas produced from nuclear interactions in a target. In the presence of nuclear materials, a beam of ions or secondary gammas will excite characteristic nuclear states that can be selectively identified by an appropriate detector array via spectral absorption or emissions. However, current ion accelerators are either too large to be transportable, or extremely lossy which leads to efficiency and activation issues. At medium to low energies, the cyclotron is the highest current accelerator due to isochronous orbits permitting CW operation. High reliability and operational simplicity are fostered by the fixed-frequency RF system and the stable and simple DC power supplies, making the conventional cyclotron the ideal choice for commercial or demanding environments. Milliamp currents and low-loss operation have been demonstrated at PSI, albeit in proton machines (charge to mass of 1) with large footprints; still these separated sector cyclotrons constitute an existence proof. RadiaBeam Systems, LLC has developed a novel more compact sector iso-cyclotron, 1.6 meters in the extraction radius, with dual, high-gradient, 0.2 MV cavities to accelerate multi-ion species up to 15-20 MeV/u with large turn-to turn, centimeter-level separation for low-loss extraction without the need for foil stripping. The machine design was optimized for nuclear security applications and is of a size and weight that it can be transported between inspection sites. Both high-field and high-gradient acceleration approach are applied to minimize the accelerator’s dimensions and cost and shielding requirements, respectively. The proposed cyclotron can accelerate all ion species with the charge-to-mass ratio of ½, from protons (in the form of H2+) to Ca20+, including a multi-species cocktail beam composed of mixed ions. High current and the ability to select an ion species is an enabling technology for the development of new screening techniques, which include delivering simultaneous beams of high-energy, monochromatic gamma and neutrons for scanning, which is not feasible with the existing machines. The Phase I design concept was made highly conservative to satisfy the requirements of most applications and can be scaled closer to technically defined limits as the application specifications evolve and various system and component designs mature. The scalable nature of the design proposed does permit scaling in all gross parameters (size, cost, energy range, etc.) to target other applications to realize a commercial product such as medical radioisotope production. In Phase I we have completed the conceptual design phase of the cyclotron, including beam dynamics optimization, 3D magnetic design, injection and extraction, and RF systems design. We have performed a review of both the potential security approaches and other commercial applications guiding our choice of optimal general parameters for the cyclotron. A conceptual engineering design was perfromed to estimate the system layout and ensure the smooth transition to a full-scale prototype design in Phase II.
- Research Organization:
- RadiaBeam Technologies, LLC, Santa Monica, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0020009
- OSTI ID:
- 1690235
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE-RBT-20009
- Country of Publication:
- United States
- Language:
- English
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