December 2024 Metallurgy Blog
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December 10, 2024
Turning Heat into Power: A Breakthrough in Thermoelectric Conversion with Tungsten Disilicide
Turning Heat into Power: A Breakthrough in Thermoelectric Conversion with Tungsten Disilicide
Scientists at Tokyo University of Science have unveiled a groundbreaking method to convert heat into electricity using tungsten disilicide (WSi₂). This pioneering work, led by Associate Professor Ryuji Okazaki, marks the first demonstration of transverse thermoelectric conversion (TTE) in WSi₂, opening new avenues for advanced thermoelectric devices.
TTE, a phenomenon that generates electricity from temperature gradients, has been gaining traction as a transformative technology for sensors measuring heat flow and temperature. However, suitable materials for TTE devices have been limited, with no established design guidelines. The discovery of WSi₂’s potential for TTE-based applications fills this gap.
The research, published in PRX Energy, employed experimental and computational methods to study the unique transport properties of WSi₂ single crystals. The team found that WSi₂’s axis-dependent conduction polarity (ADCP) stems from its distinctive electronic structure, characterized by mixed-dimensional Fermi surfaces. In this material, electrons form quasi-one-dimensional Fermi surfaces, while holes form quasi-two-dimensional surfaces, enabling direction-specific conductivity crucial for TTE.
By applying a temperature gradient at a specific angle to the crystal’s axes, researchers observed voltage generation perpendicular to the gradient, confirming the TTE effect. Using first-principles simulations, they attributed variations in electrical conductivity to imperfections in the crystal lattice, providing valuable insights for optimizing WSi₂.
This breakthrough establishes WSi₂ as a promising candidate for efficient thermoelectric devices, setting the stage for innovations in energy harvesting and heat management technologies. Learn more here.
TTE, a phenomenon that generates electricity from temperature gradients, has been gaining traction as a transformative technology for sensors measuring heat flow and temperature. However, suitable materials for TTE devices have been limited, with no established design guidelines. The discovery of WSi₂’s potential for TTE-based applications fills this gap.
The research, published in PRX Energy, employed experimental and computational methods to study the unique transport properties of WSi₂ single crystals. The team found that WSi₂’s axis-dependent conduction polarity (ADCP) stems from its distinctive electronic structure, characterized by mixed-dimensional Fermi surfaces. In this material, electrons form quasi-one-dimensional Fermi surfaces, while holes form quasi-two-dimensional surfaces, enabling direction-specific conductivity crucial for TTE.
By applying a temperature gradient at a specific angle to the crystal’s axes, researchers observed voltage generation perpendicular to the gradient, confirming the TTE effect. Using first-principles simulations, they attributed variations in electrical conductivity to imperfections in the crystal lattice, providing valuable insights for optimizing WSi₂.
This breakthrough establishes WSi₂ as a promising candidate for efficient thermoelectric devices, setting the stage for innovations in energy harvesting and heat management technologies. Learn more here.
December 23, 2024
Precision Engineering for Fusion: How a Metal Screen Boosts Plasma Heating Efficiency
Precision Engineering for Fusion: How a Metal Screen Boosts Plasma Heating Efficiency
Heating plasma to the extreme temperatures needed for fusion reactions is a complex challenge. A breakthrough by researchers at the Princeton Plasma Physics Laboratory (PPPL) demonstrates how a small tweak in metal screen alignment can make plasma heating significantly more efficient.
At the heart of the issue are helicon waves, a type of electromagnetic wave used to heat plasma. Unfortunately, generating these waves often produces unwanted "slow modes," which fail to penetrate the magnetic field confining the plasma, wasting valuable energy. Using 2D computer simulations, the PPPL team confirmed a solution: tilting the metal Faraday screen shielding the wave-producing antenna at a precise five-degree angle.
The Faraday screen plays a critical role in shaping how waves interact with plasma. Positioned correctly, the screen effectively "short-circuits" slow modes, snuffing them out before they form. The team, using the Petra-M computer code to simulate conditions in the DIII-D tokamak fusion facility, found that even slight deviations from the optimal five-degree tilt caused slow modes to grow dramatically, highlighting the precision required in screen alignment.
"This is the first time 2D simulations have confirmed how to reduce slow modes," said lead author Eun-Hwa Kim. By fine-tuning the screen's orientation, future fusion facilities could enhance wave heating efficiency, bringing fusion energy closer to reality.
With plans for further simulations incorporating more plasma properties and antenna details, this work underscores the critical role of metal components in optimizing fusion technology, paving the way for more efficient and powerful energy systems. Learn more here.
At the heart of the issue are helicon waves, a type of electromagnetic wave used to heat plasma. Unfortunately, generating these waves often produces unwanted "slow modes," which fail to penetrate the magnetic field confining the plasma, wasting valuable energy. Using 2D computer simulations, the PPPL team confirmed a solution: tilting the metal Faraday screen shielding the wave-producing antenna at a precise five-degree angle.
The Faraday screen plays a critical role in shaping how waves interact with plasma. Positioned correctly, the screen effectively "short-circuits" slow modes, snuffing them out before they form. The team, using the Petra-M computer code to simulate conditions in the DIII-D tokamak fusion facility, found that even slight deviations from the optimal five-degree tilt caused slow modes to grow dramatically, highlighting the precision required in screen alignment.
"This is the first time 2D simulations have confirmed how to reduce slow modes," said lead author Eun-Hwa Kim. By fine-tuning the screen's orientation, future fusion facilities could enhance wave heating efficiency, bringing fusion energy closer to reality.
With plans for further simulations incorporating more plasma properties and antenna details, this work underscores the critical role of metal components in optimizing fusion technology, paving the way for more efficient and powerful energy systems. Learn more here.
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