One of the world’s most advanced high-tech laser systems has been constructed at the new Center for Advanced Laser Applications (CALA). The ATLAS 3000 delivers around 25-femtosecond-long pulses whose peak power is equivalent to the power output of multiple nuclear power plants. These light pulses could provide the basis for new directions in medical technology. They could lead medical imaging and cancer therapies into a new era. The ATLAS 3000 is being developed by Thales Optronique and the working group led by Prof. Stefan Karsch, who introduces the new laser system in this interview.
Prof. Karsch, could you outline the basic data of the new laser?
The ATLAS 3000 will provide light pulses with a peak power of 2-3 petawatts (1015 W). More specifically, once per second it releases an energy of 60 joules within about 25-30 femtoseconds. 60 joules is approximately equal to the energy required to lift a full beer stein up to a height of three meters, and 30 femtoseconds is the time is takes light to travel a distance equivalent to 1/10 of the diameter of a human hair. Thus, quite a considerable amount of energy is released in an extremely short time to achieve this high peak power.
How can we classify the power of the light pulses – how “strong” are they?
2-3 petawatts corresponds roughly to the electrical output of two million nuclear power plants (or 2 billion wind turbines). If this output were to be released continuously, it would exceed the total average power of all power plants worldwide by about a factor of 1000. For this reason, such power can be generated only by the storage and subsequent release of energy within an extremely short time. ATLAS 3000 is in the top group among similar short-pulse laser systems world-wide. The current most powerful operational laser has produced a peak power of just under 2 petawatts, while another system has demonstrated 5.5 petawatts, but practical viability has not been achieved. Additionally, several projects with 10 petawatt peak performance are planned.
What is the role of ATLAS 3000 at the CALA research facility?
ATLAS 3000 provides the central infrastructure for the majority of CALA’s goals in medical and physics research. It will supply four of five experimental beamlines with laser light, which are used to generate, study and apply laser-generated secondary radiation – that is, to produce high-energy charged particles and X-ray radiation.
What are the possible applications of these light pulses in medicine?
The main application of the CALA laser is the acceleration of charged particles (electrons and ions) by the extremely strong electric fields generated by the irradiation of plasma with intense laser light. Compared to conventional particle accelerators these fields are, depending on the exact conditions, a factor of ten thousand to ten million times stronger, which means the acceleration distances can be shortened accordingly. Furthermore, the strong fields confine the particle bunches into a much smaller source volume, which in the case of electrons is used to emit high-brilliance X-ray radiation. In this way, very compact accelerators as required by modern radiation diagnosis and therapy are possible.
With ion beams generated in that way, in the medium term radiation damage to healthy and tumor tissue by ultrashort pulses will be investigated, so that these beams can be used in the long term for irradiating tumors. Similar approaches are also pursued by e.g. the Dresden/Jena joint initiative Oncooptics. In addition to pure irradiation studies, CALA aims at the integrated approach of simultaneously using the brilliant X-ray radiation generated by the same laser for diagnostic and therapy-monitoring purposes before, after and even during tumor irradiation.
How good are the chances that this technology will be successful?
The CALA project is not without risk, but if successful, it might pave a viable route towards making current large and costly ion therapy centers more efficient and to link them with high-resolution X-ray imaging, thus making treatment accessible to more patients. Until then, we have what is certainly a long way to go, but researchers involved in CALA have made significant pioneering work and promising progress over the past decade. The scientists at CALA representing both Munich universities possess a unique knowledge base: not only in the field of the underlying physical processes in the field of high-intensity laser-matter interaction, but also in the investigation of the interaction of radiation with cells and novel imaging methods.
Interview: Thorsten Naeser