Engineering topics

Okamoto, A

Publications and source records attributed to Okamoto, A.

4 records

DOE OSTI2012

Development of a He{sup -} and He{sup 0} beam source for alpha particle measurement in a burning plasma

Proof of principle experiments of neutral helium beam production for alpha particle diagnostics was carried out on a test stand. Negative helium ions were produced in the Li charge exchange cell, in which stable and long time operation was possible. He{sup -} beam was accelerated to 157 keV. Finally, He{sup 0} beam was successfully produced after the flight in the drift-tube through the auto-electron-detachment process from He{sup -} to He{sup 0}. A neutral beam detector using a pyroelectric device was also developed to measure He{sup 0} beam intensity. The metastable component in the neutral helium beam was found to be less than 2%.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2012

An alpha particle measurement system using an energetic neutral helium beam in ITER (invited)

An energetic helium neutral beam is involved in the beam neutralization measurement system of alpha particles confined in a DT fusion plasma. A full size strong-focusing He{sup +} ion source (2 A, the beam radius of 11.3 mm, the beam energy less than 20 keV). Present strong-focusing He{sup +} ion source shows an emittance diagram separated for each beamlet of multiple apertures without phase space mixing, despite the space charge of a beamlet is asymmetric and the beam flow is non-laminar. The emittance of beamlets in the peripheral region was larger than that of center. The heat load to the plasma electrode was studied to estimate the duty factor for the ITER application.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2012

Extraction of a strongly focusing He{sup +} beam from three-stage concave electrodes for alpha particle measurement system in ITER

A strongly focusing He{sup +} ion beam source equipped with concave multi-aperture electrodes was developed for production of He{sup -} through a charge exchange cell. The beam was extracted at a voltage less than 20 kV from 301 apertures distributed in an area of 100 mm {phi}, and focused at 750 mm distance. The beam current and the beam size of 2 A and 20 mm in diameter, respectively, were achieved with an arc power less than 10 kW. The optimum perveance was obtained at 0.02 A/kV{sup 1.5} at the beam energy less than 20 keV which is suitable for the conversion to He{sup -} in an alkali vapor cell.

43 PARTICLE ACCELERATORS↗

DOE OSTI2011

THE {gamma}SF METHOD

The {gamma}-ray strength function ({gamma}SF) interconnects radiative neutron capture and photoneutron emission as a common ingredient in the statistical model. Outlined here is an indirect method of determining radiative neutron-capture cross sections for unstable nuclei based on the {gamma}-ray strength function. Application examples of the {gamma}SF method are demonstrated.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗