Manufacturing Bits: April 5

Food in 3D; neutron microscopes; world’s brightest X-ray laser.


Food in 3D
Using a technology called ptychographic X-ray computed tomography, the University of Copenhagen and the Paul Scherrer Institute have taken images of food in three dimensions and on a nanometer scale.

Ptychography, a lensless coherent imaging technique, could potentially save the food industry money. It could reduce food waste due to faulty production methods. Ptychography could also be used in the electronics sector as well.

To create 3D images of food, researchers used the Swiss Light Source (SLS) synchrotron at the Paul Scherrer Institute. The SLS, a third-generation synchrotron light source, boasts an energy level of 2.4 GeV. With the technology, researchers can probe and penetrate the surfaces of new structures.

With ptychographic techniques, researchers developed images of cream, which is based on vegetable fat. The sample was placed in a thin capillary tube, which is 20 to 30 microns in diameter. Then, X-ray beams were focused at the cream sample.

Ptychographic X-ray computed tomography (Illustration: Mikkel Schou Nielsen)

Ptychographic X-ray computed tomography (Illustration: Mikkel Schou Nielsen)

3D image of the sample were then calculated. Researchers found that 98% of the fat globules in the cream were cemented together in a continuous 3D network.

Until now, researchers could only see the images in 2D. Now, they can begin to understand how the various ingredients are linked. “There is still a lot we don’t know about the structure of food, but this is a good step on the way to understanding and finding solutions to a number of problems dealing with food consistency, and which cost the food industry a lot of money,” said Jens Risbo, an associate professor at the University of Copenhagen, in a statement.

“It’s about understanding the food structure and texture. If you understand the structure, you can change it and obtain exactly the texture you want,” Risbo said.

Greyscale image shows the electron density in  various food components. (Illustration: Mikkel Schou Nielsen)

Greyscale image shows the electron density in various food components. (Illustration: Mikkel Schou Nielsen)

Neutron microscopes
The National Institute of Standards and Technology (NIST) is building a new class of neutron microscopes.

The neutron itself is a subatomic particle. It has no electric charge and a mass slightly larger than a proton. Neutrons react in different ways to various materials.

NIST’s system would advance the field of neutron imaging. A neutron microscope could be used to image structures in lithium batteries, hydrogen fuel cells, strain within metals, among others.

NIST has reached a new milestone for the technology. The agency has devised a neutron lens for the system. The first prototype should be ready this summer.

The lens, dubbed a Wolter optic, is a series of conical mirrors. They are made of thin layers of polished nickel. In the microscope, a beam of neutrons penetrates an object. Then, they pass through the lens. Some neutrons will hit a shell of the lens at a shallow angle. The neutrons are used to create a magnified image of the object.

Diagram shows the working principle of a Wolter lens (Source: NIST)

Diagram shows the working principle of a Wolter lens (Source: NIST)

When complete, the optic will consist of about 10 nested mirror shells. It will have a maximum diameter of about 15 cm and a total length of about 20 cm (about 8 in). It should have a resolution of 20 micrometers.

In one application, this system could shed light on the processes inside hydrogen fuel cells. This involves the catalyst layer, where the hydrogen fuel and oxygen from the atmosphere are combined. “The catalyst’s layer is on the order of 1 to 10 micrometers, which is beyond our current spatial resolution,” said Dan Hussey of NIST, on the agency’s site. “Being able to see inside the catalyst layer and understand the water transport in hydrogen fuel cells would be huge.”

World’s brightest X-ray laser
The Department of Energy’s SLAC National Accelerator Laboratory has begun construction on the world’s brightest X-ray laser.

The project, known as LCLS-II, will increase the power and capacity of SLAC’s current X-ray free-electron laser, dubbed the Linac Coherent Light Source (LCLS). With X-ray pulses a billion times brighter than predecessor X-ray sources, LCLS can measure the properties of ultrafast processes at the scale of atoms and molecules.

The LCLS-II is 10,000 times brighter than LCLS. LCLS-II is 8,000 times faster than the current system. The new X-ray laser will work in parallel with the existing one. Each one occupies one-third of SLAC’s 2-mile-long linear accelerator tunnel.

Like the existing facility, LCLS-II will use electrons accelerated to nearly the speed of light. This, in turn, will generate beams of bright X-ray laser light. The electrons fly through a series of magnets. This, in turn, forces them to travel a zigzag path and give off energy in the form of X-rays.

For the LCLS, electrons are accelerated down a copper pipe that operates at room temperature. It allows the generation of 120 X-ray laser pulses per second.

LCLS-II is much different. For LCLS-II, SLAC will install a superconducting accelerator. The niobium metal cavities within the accelerator will conduct electricity with nearly zero loss when chilled to minus 456 degrees Fahrenheit. “LCLS-II will take X-ray science to the next level, opening the door to a whole new range of studies of the ultrafast and ultrasmall,” said LCLS Director Mike Dunne, in a statement. “This will tremendously advance our ability to develop transformative technologies of the future, including novel electronics, life-saving drugs and innovative energy solutions.”

LCLS-II is scheduled to begin operations in the early 2020s.

A prototype of a novel electron source for LCLS-II. (Source: SLAC)

A prototype of a novel electron source for LCLS-II. (Source: SLAC)

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