BELLA (laser)
{{Short description|Laser developed by the Thales Group}}
The Berkeley Lab Laser Accelerator (BELLA) is a laser built by the Thales Group and owned and operated by the Lawrence Berkeley National Laboratory.{{cite web |url=http://www.photonics.com/Article.aspx?AID=51563 |title=Petawatt Laser Achieves Record Power |date=1 August 2012 |work=Photonics.com |accessdate=14 September 2012}}{{cite web |url=http://newscenter.lbl.gov/news-releases/2012/07/27/bella-laser-record-power/ |title=BELLA Laser Achieves World Record Power at One Pulse Per Second |author=Paul Preuss |date=July 27, 2012 |work=Berkeley Lab News Letter |publisher=Lawrence Berkeley National Laboratory |accessdate=14 September 2012}} On 20 July 2012, BELLA fired a 40 femtosecond laser pulse, establishing a world record for most powerful laser.{{cite journal |last=Heirbaut |first=Jim |date=31 August 2012 |title=Surfen op plasmagolven |trans-title=Surfing on waves of plasma |journal=De Ingenieur |volume=124 |issue=13 |page=11 |publisher=Veen Magazines |editor1-first=Erwin |editor1-last=van den Brink |language=Dutch |issn=0020-1146 }}
BELLA was designed and built by Thales as part of the Laser and Optical Accelerator Systems Integrated Studies (LOASIS) program at LBNL. The LOASIS group studies the application of high-powered lasers to build compact particle accelerators. The BELLA laser was developed for the purposes of studying this principle. The idea is that a laser which delivers a large amount of power in a very short pulse can cause ionization in a gas followed by plasma oscillation. As a result the gas will emit electron bundles which can be used for medical imaging or materials research.
On 20 July 2012, BELLA fired a laser pulse with a duration of 40 femtoseconds and a repetition frequency of 1 hertz. The pulses had a compressed output energy of 42.2 joule, making the power output of the laser 1 petawatt:
{42.2 J \over 40 fs} = {42.2 J \over 40*10^{-15} s} \approx 1*10^{15} J/s = 1 PW
This result established BELLA as the highest peak power laser in the world (at a 1 Hz repetition rate).
In December, 2014, a team of researchers accelerated electrons using BELLA up to an energy of 4.25 GeV—the absolute highest energies recorded to date using a compact accelerator.{{cite web |url=http://marketbusinessnews.com/berkeley-lab-laser-accelerator-breaks-particle-acceleration-record/40368 |title=Berkeley Lab Laser Accelerator breaks particle acceleration record |author=Joseph Nordqvist |date=December 9, 2014 |publisher=Market Business News |accessdate=10 December 2014}}