Thursday, November 20, 2014

Shooting water droplets with powerful lasers

"The energy deposition in a liquid drop on a nanosecond time scale by impact of a laser pulse can induce various reactions, such as vaporization or plasma generation. The response of the drop can be extremely violent: The drop gets strongly deformed and propelled forward at several m/s, and subsequently breaks up or even explodes. These effects are used in a controlled manner during the generation of extreme ultraviolet (EUV) light in nanolithography machines for the fabrication of leading-edge semiconductor microchips. Detailed understanding of the fundamentals of this process is of key importance in order to advance the latest lithography machines."

"In this video we show the impact of a focused laser pulse onto a millimeter-size drop in a regime comparable to what can be found in lithography machines. The drop’s life was recorded for various impact conditions by high-speed imaging at 20 000 frames per second (FPS). The high reproducibility of the dynamics allowed us to use stroboscopic illumination with nanosecond exposure times leading to an effective frame rate of 10 million FPS. We present a scaling law and compare experimental results to numerical simulations, in order to show how the drop is propelled and deformed."

Authors: Alexander L. Klein, Wilco Bouwhuis, Claas Willem Visser, Henri Lhuissier, Chao Sun, Jacco H. Snoeijer, Emmanuel Villermaux, Detlef Lohse, and Hanneke Gelderblom

Monday, November 17, 2014

Friday, November 7, 2014

Indian rockets update

"A group in the Aerospace Engineering department at the International Indian University in Navi Mumbai, India has established a sounding rocket program that has achieved altitudes of 4.5 km, 10 km, and 40 km with their rockets. I’m told by Rajesh Muneshwar, head of the department, that their rockets are powered by a sugar based solid fuel. He also says the public demonstrations of the launches 'are thrilling, motivating and attracting more students to develop ROCKETS.'"

See the full report here.

Monday, November 3, 2014

Improving WiFi reception using science

"A few posts back I was concerned with optimising the WiFi reception in my flat, and I chose a simple method for calculating the distribution of electromagnetic intensity. I casually mentioned that I really should be doing things more rigorously by solving the Helmholtz equation, but then didn’t. Well, spurred on by a shocking amount of spare time, I’ve given it a go here."

Sunday, November 2, 2014

Saturn rocket engines

Dropping feathers and bowling ball in world's largest vacuum chamber

Perhaps the most shocking thing to see is feathers, for the first time in the history of falling feathers, impacting a surface at 10s of meters per second. They hit pretty hard and even bounce!