Francium (Fr), which is the alkali atom in the 7th period, can be obtained as ultracold atoms with laser cooling and trapping techniques, and could be employed for the experiments on searches for the ...permanent electric dipole moment (EDM) of an electron. In order to improve the sensitivity of the electron EDM search, development of a high-intensity source of Fr atoms is essential. We demonstrated a production of a high intensity
210
Fr ion beam with a rate of
5
×
10
6
ions/s by a fusion reaction with bombardment of an accelerated
18
O beam onto a fixed gold target in RIKEN. The Fr products inside the gold target were extracted from the gold surface as an ion beam focused with an electrostatic field. We also discussed the method to produce
221
Fr by
α
-decay of
225
Ac. A neutron-rich
221
Fr isotope can be obtained as a daughter nucleus of this decay.
ASACUSA collaboration has been making a path to realize high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atom in flight for stringent test of the
CPT
...symmetry. Recently, we have succeeded in synthesizing our first cold antihydrogen atoms employing a CUSP trap. It is expected that synthesized antihydrogen atoms in the low-field-seeking states are preferentially focused along the cusp magnetic field axis whereas those in the high-field-seeking states are not focused, resulting in the formation of a spin-polarized antihydrogen beam. We report the recent results of antihydrogen atom synthesis and beam production developed with the CUSP trap.
ASACUSA collaboration has been making a path to realize high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atom in flight for stringent test of the CPT ...symmetry. Recently, we have succeeded in synthesizing our first cold antihydrogen atoms employing a CUSP trap. It is expected that synthesized antihydrogen atoms in the low-field-seeking states are preferentially focused along the cusp magnetic field axis whereas those in the high-field-seeking states are not focused, resulting in the formation of a spin-polarized antihydrogen beam. We report the recent results of antihydrogen atom synthesis and beam production developed with the CUSP trap.
This paper presents a lumped element model (LEM) to describe the coupled dynamic properties of thermomagnetic generators (TMGs) based on magnetic shape memory alloy (MSMA) films. The TMG generators ...make use of the concept of resonant self-actuation of a freely movable cantilever, caused by a large abrupt temperature-dependent change of magnetization and rapid heat transfer inherent to the MSMA films. The LEM is validated for the case of a Ni-Mn-Ga film with Curie temperature T
of 375 K. For a heat source temperature of 443 K, the maximum power generated is 3.1 µW corresponding to a power density with respect to the active material's volume of 80 mW/cm
. Corresponding LEM simulations allow for a detailed study of the time-resolved temperature change of the MSMA film, the change of magnetic field at the position of the film and of the corresponding film magnetization. Resonant self-actuation is observed at 114 Hz, while rapid temperature changes of about 10 K occur within 1 ms during mechanical contact between heat source and Ni-Mn-Ga film. The LEM is used to estimate the effect of decreasing T
on the lower limit of heat source temperature in order to predict possible routes towards waste heat recovery near room temperature.
Thermomagnetic (TM) generators based on Heusler alloy films have the potential to recover waste heat below 200°C at small temperature differences . Progress in the development of materials that ...exhibit large abrupt changes in ferromagnetic ordering and in film engineering enable efficient thermomagnetic generation via resonant self-actuation of freely movable film-based devices. Yet, power levels of individual devices are low, and upscaling becomes a key issue of material development and engineering. Here, we address the key question of how film thickness and device footprint affect power and efficiency. We investigate the scaling performance of heat intake, heat dissipation, and resulting local temperature changes. Based on this understanding, the electrical power per footprint could be increased by a factor of 3.4. Maximum values of electrical power per footprint are 50 μW/cm2 at a temperature change of only 3°C, which marks an important milestone in the upscaling of Heusler alloy film-based TM generators.
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•Scaling performance of heat transfer dynamics during resonant self-actuation•Scaling effect of film thickness and device footprint on power and efficiency•Electrical power per footprint increases with film thickness by a factor of 3.4•Electrical power per footprint reaches 50 μW/cm2 at a temperature change of 3°C
Waste heat is a growing and abundant energy resource, particularly at low temperature below 200°C, which is difficult to recover by existing energy conversion technologies. Progress in the development of films that exhibit large abrupt changes in magnetization and rapid heat transfer unclose the development of thermodynamically efficient thermomagnetic generators. Detailed experiments and lumped element simulations for the case of Heusler alloy film Ni-Mn-Ga show that scaling of film thickness and device footprint oppositely affect power output. Based on this understanding, we could increase the electrical power per footprint by a factor of 3.4 for increasing film thickness from 5 to 40 μm reaching values of 50 μW/cm2 at a temperature change of only 3°C. These results pave the way for the development of advanced generators consisting of parallel architectures with tailored footprint and films operating well below 100°C that open up waste heat recovery near room temperature.
State-of-the-art thermomagnetic generators (TMGs) suffer from the limited temperature-dependent change of magnetization ΔM/ΔT and/or limited heat transfer dynamics. This shortcoming could be overcome by TMGs based on Heusler alloy films that exhibit large ΔM/ΔT and rapid heat transfer due to resonant self-actuation. Yet, power levels of individual devices are low, and upscaling becomes a key issue of material development and engineering. Here, we elucidate the heat transfer dynamics during resonant self-actuation and demonstrate how to optimize power output per footprint.
A material that can capture changes in environmental stimuli as a color change can be used to develop sensors and displays. By producing an ordered structure in a polymer gel that reflects particular ...wavelengths of light, we can express the volume change that occurs based on the environment as the change in the wavelength of reflected light, i.e., structural color. To date, many systems have been developed to change the hue of the structural color as a function of temperature, pH, substance, applied force, and so on. However, as is expected from the principle of optical interference, the gel usually shows a red-shift with increasing volume. In this study, we propose a method for preparing structurally colored stimuli-responsive polymer gels that display appropriate color changes according to changes in environmental stimuli. For this purpose, we employ the photonic balls, which are spherical colloidal crystals consisting of monodisperse silica particles, as templates. By combining the wavelength-selective reflection generated from different photonic band gaps of the photonic balls, we succeeded in developing porous stimuli-responsive polymer gels that exhibited various types of color change, which are not observed in conventional systems.
We present the design, simulation, and characterization of a magnetic shape-memory alloy (MSMA) film actuator that transitions from bistable switching to resonant self-actuation when subjected to a ...stationary heat source. The actuator design comprises two Ni-Mn-Ga films of 10 µm thickness integrated at the front on either side of an elastic cantilever that moves freely between two heatable miniature permanent magnets and, thus, forms a bistable microswitch. Switching between the two states is induced by selectively heating the MSMA films above their Curie temperature Tc. When continuously heating the permanent magnets above Tc, the MSMA film actuator exhibits an oscillatory motion in between the magnets with large oscillation stroke in the frequency range of 50–60 Hz due to resonant self-actuation. A lumped-element model (LEM) is introduced to describe the coupled thermo-magnetic and magneto-mechanical performance of the actuator. We demonstrate that this performance can be used for the thermomagnetic energy generation of low-grade waste heat (T < 150 °C) with a high power output per footprint in the order of 2.3 µW/cm2.
This paper presents an investigation of the heat transfer processes in miniature thermomagnetic generators (TMGs) that are based on the recently developed concept of resonant self-actuation of a ...cantilever enabling efficient conversion of thermal into electrical energy. A lumped element model (LEM) is introduced to describe the dynamics of heat intake during mechanical contact between a thermomagnetic (TM) film and heat source, and of heat dissipation. The key parameters governing heat intake and dissipation are the heat transfer coefficient at contact and the thermal resistance Rb of the bonding layer between TM film and cantilever, respectively. The effects of these parameters on the performance metrics are investigated for different heat source temperatures above the Curie temperature of the TM film. LEM simulations reveal critical values of κ and Rb, above which stable performance of energy generation occurs characterized by large stroke and frequency resulting in large power.
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•Resonant self-actuation enables efficient thermomagnetic energy conversion•A minimum temperature change (ΔT, here:6K) is required for resonant self-actuation•Heat intake and ΔT strongly decrease below a critical heat transfer coefficient•Low thermal resistance reduces heat dissipation and thus ΔT
Thermal design; Thermal engineering; Thermal property; Thermomagnetic; Energy harvesting; Heusler alloys; Resonant self-actuation; Thermal processes
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