Tuesday, October 09, 2012

Lasers, plasmas and diffusers

The first laser, invented in 1960 by Theodore Maiman, an engineer-turned-physicist, was a product of the aerospace industry. Maiman was working for Hughes Research Laboratories, and was given nine months and $50,000 to make a laser work by Mr Hughes, (And then there was light, Pauline Rigby, Physics World, May 2010).

Perhaps it's time, then, for the introduction of the laser into Formula One, not merely as a ride-height sensor, but as a flow control device.

Racing cars have, traditionally, used the short-range repulsive forces of solid surfaces to control the flow of air. This, however, is merely one particular, very convenient solution to the engineering problem. Lasers can also control the flow of air, either by directly delivering radiation pressure to a specific region of the airflow, or by creating a plasma whose pressure can instead be used to the same effect.

The question here is merely one of practicality. Do modern lasers combine sufficient power in a lightweight, compact package? Well, probably not quite yet, but there are already some tantalising glimpses of the possibilities.

The Curiosity Rover currently exploring Mars is equipped with a Laser-Induced Breakdown Spectroscopy (LIBS) system. The laser vaporises rocks some distance away, and a separate camera system analyses the light to make inferences about the chemical composition of the rock. Most intriguingly, the weight of this powerful laser system was reduced to 500g.

A LIBS system focuses a laser on an object and ablates the surface layer of the object to create a plasma plume. This high-temperature plume has a momentum flux, and it has long been suggested that this could be used to propel lightweight objects.

In terms of an immediate Formula One application, however, one might install a laser unit low down in the aft region of the sidepods, and train the laser light upon an aluminium foil surface attached to the floor in the region where one currently finds vortex generators, just inside the rear wheel. The resulting plasma plume could be used as a surrogate exhaust jet to seal the diffuser, with perhaps the odd magnet to focus the plasma. Depending upon how the regulations evolve, KERS energy could be used to power the laser.

There are some potential hazards, such as the possibility of vaporising the rear end of the car if the laser is incorrectly focused, but these are small matters in comparison to the potential advantages of a laser-sealed diffuser system.


Sean said...

The fusion power project people are having the same problem with the focusing of the laser.

I would have thought going round corners at 160mph presents even more of a challenge.

Gordon McCabe said...

I think the focusing requirements for fusion are rather more exacting, but we'd certainly need to ensure that the laser is rigidly mounted and free from excessive vibration.

corner1 said...

could a modern, non-MARS spec laser be used to heat the tires during a race?

Gordon McCabe said...

I suppose it could. Heating the rear tyres up, however, is probably not something you'd want to do!