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A fiber optic bolometer (FOB) was demonstrated observing a fusion plasma for the first time at the DIII-D tokamak. A FOB uses a fiber optics-based interferometric technique that is designed to have a high sensitivity to temperature changes [75 mK/(W/m2) responsivity in high vacuum with 0.38 mK noise level] with a negligible susceptibility to electromagnetic interference (EMI) that can be problematic for resistive bolometers in a tokamak environment. A single-channel test apparatus was installed on DIII-D consisting of a measurement FOB and shielded reference FOB. The single-channel FOB showed a negligible increase in the noise level during typical plasma operations (0.39 mK) compared to the benchtop results (0.38 mK), confirming an insignificant EMI impact to the FOB. Comparisons to DIII-D resistive bolometers showed good agreement with the single-channel FOB, indicating that the FOB is comparable to a resistive bolometer when the impulse calibration is applied. The noise-equivalent power density of the calibrated FOB during a plasma operation was 0.55 W/m2 with an average sampling time of 20 ms. The major potential effect of ionizing radiation on the FOB would be the radiation-induced attenuation, which can be efficiently compensated for by adjusting the probing light power. [ABSTRACT FROM AUTHOR]

Presents information on a study that probed the development of magnetic ordering in correlated-electron uranium systems. Experimental procedure; Results and discussion; Conclusion.

Presents a study which predicted the triggering of an instability from unusual anisotropic, well-ordered, magnetism to an unstable state. Delocalization for rare earths; Key to understanding solid-state behavior in the transitional regime between localized and delocalized f-electron behavior; Approaches in building a unified phenomenological and electronic structure theory; Description of the change in behavior from CeSb to CeTe; Prediction of valence fluctuation behavior for CeN.

Presents a study that discussed the characteristics of correlated ƒ-electron systems. Techniques in the calculation of ƒ-electron systems; Properties of the systems; Degree of localization of the rare-earth monopnictides.

Presents information on a study which described a scheme for calculating the hybridization and exchange effects of magnetic ordering in correlated-electron uranium systems. Analysis of the varied electron phenomena in cerium and light actinide compounds; Methodology of the study; Results and discussion.

Focuses on the importance of all consequences of the Coulomb interaction which contribute to the two-ion interaction. Derivation of the expression for the two-ion interaction; Significance of the Thomas-Fermi theory.

Presents a study which reported on a technique involving a nonconventional electronic structure calculation based on treating the ƒ electron as a resonant state in solid-state environment to evaluate hybridization. Procedure for evaluating the hybridization; Calculation of the crystal-field level shifts and two-ion exchange interaction matrix.

Proposes a theory which organize the diverse magnetic behavior into a unified picture describable through one Hamiltonian model. Approaches used in treating the correlated f-electron systems; Concept of Kondo resonance-Kondo compensation; Key elements of the Kondo problem; Description of the atomic Hamiltonian; Information on the two-component spectrum near the Fermi level.

Presents information on a study which investigated the origins in the electronic structure and magnetic ordering on going from CeIn[sub3], a local moment antiferromagnetic system, to CePb[sub3], heavy fermion itinerant antiferromagnetic system, both of which Cu[sub3]Au crystal structure. Energy windows employed to allow coverage of various subbands; Band structure of CeIn[sub3]; Quantities arising from the band structure calculations.

Presents a study which investigated the origins in the electronic structure of the variation in magnetic behavior as the degree of 5 ƒ-electron localization changes from localized to itinerant on going up the pnictogen or chalcogen column causing uranium-uranium separation. Discussion on the magnetic properties and electronic structure of uranium monopnictides and monochalcogenides; Calculation of the band structure of uranium arsenic; Results of the linear-muffin-tin-orbital method.

Fiber-optic bolometers (FOBs) intended for plasma radiation measurement in magnetically confined fusion have been previously developed using a silicon pillar that functions as both a Fabry-Perot interferometer (FPI) for temperature measurement and an absorber for the radiation. We report an FOB design that can significantly improve the detection sensitivity over earlier designs by engineering the absorber of the FOB. Our design uses the fact that, compared with a silicon pillar, a gold film with the same x-ray absorption thickness will show a much higher temperature rise from a given power density of the radiation. Therefore, the responsivity of an FOB can be improved by attaching a large gold disk to the silicon FPI as the absorber. We have developed a fabrication method for FOBs of such design and obtained an FOB with a 4-µm-thick, 0.6-mm-diameter gold disk attached to a 200-µm-diameter, 100-µm-thick silicon FPI. We have characterized the noise, responsivity, response time, and noise-equivalent power density (NEPD) and compared these with the earlier design where the absorber is mainly the silicon FPI itself. The experimental result suggests that the FOB with the gold disk achieves a responsivity of ∼2.8 mK/(W/m 2 ) and a noise-equivalent-power-density of 0.13 W/m 2 , which are, respectively, more than nine times larger and six times smaller compared to the FOB using a previous design. Improved NEPD and good absorption over a broad frequency range will make the FOB more attractive for applications in magnetic-confinement fusion devices.

We report a fiber-optic bolometer based on a high-finesse silicon Fabry-Perot interferometer (FPI). The silicon FPI absorbs and converts the incident radiation into temperature variations, which are interrogated by the shift of the reflection spectrum of the FPI. The FPI is a silicon pillar with one side coated with a high-reflectivity dielectric mirror and the other side coated with a gold mirror. A multimode fiber collimator is applied between the FPI and lead-in single-mode fiber to reduce the round-trip diffraction loss, giving rise to a high-finesse of 35 of the FPI. The sensor is demodulated using a low-cost distributed feedback diode laser. A dummy bolometer was used to effectively reduce the common noises from the laser wavelength drift and ambient temperature variations. Experimental results show that, compared with a previously reported fiber-optic bolometer, the one reported here has a 5-fold decrease in noise and a 7-fold increase in responsivity with a noise equivalent power density (NEPD) of 0.27 W/m 2 , which is comparable with the NEPDs of the state-of-the-art resistive bolometers.

Surface charge distribution is a crucial factor for the ionic transport properties inside nanopores. Modifying the surface charge inside a single conical nanopore can greatly affect the rectification behavior of the ionic current through the nanopore and afford nanofluidic diodes. In this work, we describe a new method to fabricate nanofluidic diodes by atomic layer deposition (ALD) on conical track-etched nanopores. Thorough investigation of the ionic transport behavior through ALD-modified polyethylene terephthalate (PET) nanopores is carried out. Our results demonstrate that ALD is a simple and effective method to modify the inner surface of the polymer nanopores for fabricating nanofluidic devices. In addition, we also investigate the stability of the ALD-modified nanopores, and the results suggest that the long-time stability could be compromised by high voltage applied along the nanopore.