A thyristor will stay conducting until the current through the device is zero (“current zero”) or perhaps slightly negative. LLNL’s approach is to use the opticondistor (“OTV”) to force this current zero in order to force the device into an “off” state. By combining a light-activated thyristor with an OTV, a noise-immune, high efficiency, high-power switching device can be constructed. The…
Keywords
- Show all (102)
- Additive Manufacturing (37)
- Imaging Systems (9)
- 3D Printing (7)
- Semiconductors (6)
- Optical Switches (4)
- Power Electronics (3)
- Sensors (3)
- Computing (2)
- Manufacturing Automation (2)
- MEMS Sensors (2)
- Optical Sensors (2)
- Particle Accelerators (2)
- Precision Engineering (2)
- Spectrometers (2)
- Synthesis and Processing (2)
- Manufacturing Simulation (1)
- Volumetric Additive Manufacturing (1)
- (-) Photoconductive Semiconductor Switches (PCSS) (9)
- (-) Electric Grid (3)
- (-) Manufacturing Improvements (3)
![A cross-sectional schematic of a diffused Ga2O3 photoconductive semiconductor switch (PCSS)](/sites/default/files/styles/scale_exact_400x400_/public/2024-02/a%20cross-sectional%20schematic%20of%20a%20diffused%20beta-Ga2O3%20PCSS.png?itok=Z41s0FbO)
The researchers’ approach leverages the concept that dopants have high diffusivities in Ga2O3; the key lies in the selection of the appropriate dopant. This LLNL invention describes two device types that employ this design:
![Samples of optimized diamond switches](/sites/default/files/styles/scale_exact_400x400_/public/2024-01/Samples%20of%20optimized%20diamond%20switches.png?itok=5syzdD0q)
Design and construction of a photoconductive switch requires a diamond photoconductor illuminated by light of a certain excitation wavelength.
Characteristics of the LLNL-developed switch are as follows:
![Custom PCB design of a PCSS Laser Diode Driver](/sites/default/files/styles/scale_exact_400x400_/public/2023-11/PCSS%20Laser%20Diode%20Driver.png?itok=WQ2FNHQF)
LLNL researchers have invented an ultrafast PCSS to drive a high-power laser diode with arbitrary pulse widths. These devices operate by supplying a high voltage (>10 kV) to one side of the switch. A short pulse of light illuminates the semiconductor, instantly turning it from highly resistive to highly conductive.
![LLNL energy grid protection device](/sites/default/files/styles/scale_exact_400x400_/public/2023-10/LLNL%20energy%20grid%20protection%20device_0.png?itok=vpqzRY_R)
The approach is to leverage the fact that a momentary “load” equal to the power transmission line impedance, (Z0), during the transient can suppress its propagation. Z(0) is typically a fixed impedance of several hundred ohms based on the geometry of most single wire transmission lines.
So, an isolated self-powered opticondistor (OTV) system may provide an ultrafast method of…
![Electrodeposition of Zn onto 3D printed copper nanowire (CuNW)](/sites/default/files/styles/scale_exact_400x400_/public/2023-07/ElectrodepositionofZnon3dprintedCuNW.jpg?itok=2G2D1kt9)
Improving the active material of the Zn anode is critical to improving the practicality of Zn-MnO2 battery technology. LLNL researchers have developed a new category of 3D structured Zn anode using a direct-ink writing (DIW) printing process to create innovative hierarchical architectures. The DIW ink, which is a gel-based mixture composed of zinc metal powder and organic binders, is extruded…
![twister oven component with reflective inner cylinder surface](/sites/default/files/styles/scale_exact_400x400_/public/2023-06/twister%20oven%20component.png?itok=v3jlzm2V)
U.S. Patent No. 11,555,965 describes LLNL’s invention of “Illumination Frustums” for photoconductive switches to capture and “frustrate” the light from leaving the frustum. LLNL researcher’s latest novel invention, “Twister Oven”, achieves this by encouraging laser light absorption in a photo conductor material. Light enters the oven twisting and reflecting, making near normal incident multi…
![A digital twin (right) is the virtual representation of real-world objects and processes (left)](/sites/default/files/styles/scale_exact_400x400_/public/2023-06/DigitalTwin.jpg?itok=SkQtz1w4)
LLNL’s novel approach utilizes a number of techniques to improve reconstruction accuracy:
![A photoconductive switch made from a synthetic, chemical vapor deposition diamond under test](/sites/default/files/styles/scale_exact_400x400_/public/2023-06/Photoconductive%20switch.jpg?itok=xC1O7vXg)
Design and construction of a photoconductive switch requires a diamond photoconductor illuminated by light of a certain excitation wavelength. The diamond material is chosen to be doped with substitutional nitrogen to act as a source of electrons. The device architecture allows maximum light entering the aperture. The top and bottom electrodes are made of ultra-wide bandgap (UWBG)…
![schematic of LLNL’s field emission photocathode device architecture with examples of tunable SiC surface micro- and nanostructures fabricated at LLNL](/sites/default/files/styles/scale_exact_400x400_/public/2023-05/FE%20photocathode%20device.png?itok=z-1Om9v8)
LLNL researchers faced this challenge by bridging the gap between VEDs and solid-state electronics (SSE). Their approach was to create a hybrid vacuum microelectronic device (VMD) architecture that combines the properties of vacuum as the electronic medium and the compact form factor and manufacturing scalability of semiconductor microelectronic chips.
![Segments of transmission line lengths can be switched to open circuit (as shown) or shorted to the ground (not shown)](/sites/default/files/styles/scale_exact_400x400_/public/2023-05/Segments%20of%20tranmission%20line%20lengths.png?itok=FF0qaBGw)
Design and construction of a photoconductive switch requires a diamond photoconductor illuminated by light of a certain excitation wavelength. The diamond material is specifically doped with substitutional nitrogen, which act as a source of electrons. The device architecture allows maximum light entering the aperture. The top and bottom electrodes are made of ultra wide band gap (UWBG)…
![Annular illumination on photo conductor by Conical Total Internal Reflection “CTIR” endcap](/sites/default/files/styles/scale_exact_400x400_/public/2023-05/CONIFR.png?itok=L4wSanXF)
The approach is to use a custom-designed frustrum and attach it to the optical fiber that connects to the PCSS. Light from the fiber enters the frustrum, spreads out, and enters the PCSS. Any unabsorbed light re-enters the frustrum and, because of its geometry, reflects back into the PCSS itself with only a negligible fraction escaping from the fiber. The shape of the novel frustrum is…
![A cold-spray chamber is shown during deposition, with the nozzle at the top of the image and a near-full density sample being fabricated in the center. Particles of the brittle thermoelectric bismuth telluride are accelerated to more than 900 meters per second, or almost Mach 3, in inert gas and directed onto a copper surface, laying down the strips that form the basis of a functioning thermoelectric generator to harvest waste heat. Graphic by Jacob Long/LLNL](/sites/default/files/styles/scale_exact_400x400_/public/2021-02/Cold%20Spray_875x500px.jpg?itok=hjM9UrWO)
![Intensification of laser in simulations and electrons being accelerated](/sites/default/files/styles/scale_exact_400x400_/public/2022-06/intensification%20of%20laser%20in%20simulations%20and%20electrons%20being%20accelerated_875x500px.jpg?itok=bdZS_mHA)
LLNL pioneered the use of tomographic reconstruction to determine the power density of electron beams using profiles of the beam taken at a number of angles. LLNL’s earlier diagnostic consisted of a fixed number of radially oriented sensor slits and required the beam to be circled over them at a fixed known diameter to collect data. The new sensor design incorporates annular slits instead,…