Vacuum tube (old technology to make Electronics to get a whole lot faster without semiconductors )

Researchers are re purposing decades-old technology to build faster gadgets for the future, creating nano scale

Researchers are re purposing decades-old technology to build faster gadgets for the future, creating nano scale vacuum tubes that could dramatically improve the speed and efficiency of personal electronics and solar panels.

Vacuum tubes were originally used in the earliest digital electronic computers back in the 1930s and 1940s, before being replaced by transistors composed of semiconductors, which can can be manufactured much smaller, making today's computers, smartphones, and tablets possible.

that could dramatically improve the speed and efficiency of personal electronics and solar panels.

Vacuum tubes were originally used in the earliest digital electronic computers back in the 1930s and 1940s, before being replaced by transistors composed of semiconductors, which can can be manufactured much smaller, making today's computers, smartphones, and tablets possible.

But transistors have their limits in size and speed too, and we're getting closer than ever to reaching them. Now scientists from UC San Diego have gone back to the vacuum tube idea - and this time they've made them at tiny sizes and with far more efficient technology.

"This certainly won’t replace all semiconductor devices, but it may be the best approach for certain specialty applications, such as very high frequencies or high power devices," says lead researcher and electrical engineer, Dan Sievenpiper.

While transistors remain one of the most important inventions of the 20th century - and much smaller and more energy-efficient than the original vacuum tubes - scientists are now struggling to make them any tinier or more powerful than they already are.

What's more, electron flow through transistor semiconductor materials like silicon is slowed as electrons collide with atoms, and semiconductors also have what's called a band gap - where a boost of external energy is needed to get electrons moving.

The main advantage new nanoscale vacuum tubes have over semiconductor-based transistors is that they carry currents through air, rather than a solid material, and could be be much faster as a result.

 

The vacuum tube design (left), electric field enhancement (middle), and electric field distribution (right) of the new nanoscale structure. Credit: UC San Diego   

Freeing up electrons to carry currents through the air normally takes a large voltage or a powerful laser, both of which are difficult to do at the nanoscale, and which hampered the progress of early vacuum tubes.

To solve this problem, the team created a layer of special mushroom-style structures made of gold - known as an electromagnetic metasurface - and placed it on top of a layer of silicon dioxide and a silicon wafer.

When a low-powered voltage (less than 10 volts) and a low-powered laser are applied to this metasurface, it creates 'hot spots' with high-intensity electric fields, giving the structure enough energy to free the electrons from the metal.

In testing, this enabled the researchers to achieve a 1,000 percent (or 10-fold) increase in conductivity compared with nanoscale vacuum tubes without the metasurface. 

Right now, it's just a proof-of-concept demonstration, and there's a lot more work to be done to make the system practical for use in actual devices. But in the future, different metasurfaces could be designed to meet specific needs, such as new kinds of solar panels, the researchers suggest.

"Next we need to understand how far these devices can be scaled and the limits of their performance," says Sievenpiper.

Here's the team explaining their findings: Thanks: fossbytes.com and sciencealert.com

 

Benisagar: A 5th Century Vedic Hindu University

Evidence of a 5th Century AD Vedic Hindu university located at Benisagar village in West Singhbhum district (bordering Mayurbhanj in Orissa) has recently been unearthed by archaeologists. According to Mr Onkar Chauhan, archaeological superintendent of the Ranchi Chapter of the Archaeological Survey of India, the findings are based on the recovery of a seal, which bears characters of the Brahmi script belonging to the Gupta era. Mr Chauhan told The Statesman that the seal was discovered from the rain gullies of an ancient mound in August this year and is currently in the possession of a local villager. The seal, which is circular with a linear border, has a horizontal line bifurcating the motifs and the legends. The motifs are depicted on the upper half while the legends lie on the lower half. The motifs, according to Mr Chauhan, represent rosary beads, kamandalu and danda, while the legends comprise nine letters. It reads: Priyangu Dheyam Chaturvidya, translated, one who is well-versed in the four Vedas. The 5th century AD Brahmi script denotes the Sanskrit language.

Mr Chauhan said the archaeological remains of the place consist of low mounds, ruins of bricks and stone temple, apart from phallic and stone images. The mounds are scattered all over the area, but the many-layered remains converge at a particular spot known as Devasthan on the eastern embankment of a large tank - Benisagar - from which the village derives its name. The discovered seal is one that belonged to Brahmins. Mr Chauhan said that the large number of private seals discovered during excavations of Bhita and Basrah regions in Kutch bear resemblance to the Benisagar seal. In both cases, the script character used in the inscription measures 1.5 inches. While the Kutch seal dates back to the 8th century AD, the Benisagar seal belongs to the 5th century AD.
Researches revealed, the Vedic systems of learning were prevalent between 1st and 11th century AD. The four education systems included Charan, Agahara, Travidya and Chaturvidya. The seal recovered from Benisagar indicates that it was a seat of learning where the four Vedas were taught.
(source: Benisagar: A Nalanda contemporary seat of learning - Statesman News Service - October 18 2004).
Facts about Benisagar - This is situated in the border of West Singhbhum & Orissa.The place was named after the king Beni. This is famous for archaeological findings. The famous Khiching temple relate to the king Kichak of Mahabharat. According to local belief the Pandavas spent sometime over here during their Agyant Baas.

Advanced Level (A/L) Chemistry new syllabus (Tamil medium, Sri Lankan syllabus) - Mr. M.R. Fahumudeen