B. Hidding, O. Karger, T. Königstein, G. Pretzler, J.B. Rosenzweig

Research output: Book/ReportCommissioned report

### Abstract

Laser-plasma-accelerators are relatively new accelerator devices which are characterized by being very compact, which is the result of the giant electric accelerating fields present in strongly focused, high-power ultrashort laser pulses. Peak intensities of modern laser systems can reach $10^{22}\,\mathrm{W/cm^2}$ or more, which is many orders of magnitude larger than the complete sunlight incident on Earth, if it were collected and focused at the same time onto an area of a tip of a pencil. Such intensities make such laser systems attractive for many applications, as exotic as inertial confinement fusion and producing ultrashort electron beams with GeV-scale energies or advanced light sources such as free-electron lasers, or those based on inverse Compton scattering and betatron radiation. The woldwide booming community in this fields works towards these applications which have highly stringent demands on beam quality, as an alternative to well-established accelerators based on radiofrequency cavity based accelerators such as linacs (for electrons) and cyclotrons (for protons and ions). Breakthroughs were achieved in 2004, when for the first time instead of spectrally very broadband and rather divergent particle beams, pencil-like electron beams with quasi-monoenergetic electron bunch distribution were generated. Beam quality in terms of narrow energy spread and larger energies (beyond the GeV barrier) improves continuously and rapidly, fueled by progress in terms of understanding and by ever increasing laser power and technology readiness. In contrast to such highest-quality beams which are needed for example for free-electron-lasers, space radiation which harms electronics and living systems outside Earth's protective magnetic fields, is always very broadband. In fact, conventional accelerators always automatically produce very narrowband particle beams, which are unnatural. It has been proposed (and patented) for the first time in 2009 to use compact laser-plasma-accelerators to produce broadband radiation such as present in space and to use this for radiation hardness tests. Such broadband radiation is the inherent regime of laser-plasma-accelerators. The difficulty of laser-plasma-accelerators to produce monoenergetic beams is turned into a noted advantage here. Since producing broadband radiation is possible since many years with laser-plasma-accelerators, this application is one which has been ''left behind'' for many years now due to the community seeking to produce more monoenergetic beams such as with conventional accelerators.

Both fields, laser-plasma-acceleration on the one hand and space radiation testing on the other are highly vibrant fields, which have been disjunct so far. Connecting both fields, and to introduce laser-plasma-accelerators as complementary radiation sources for improved space radiation testing is highly advisable. It shall be emphasized that both the traditional radiation sources as well as laser-plasma-accelerators have inherent advantages, and that it is expected that the combination of both types of radiation sources will be highly fruitful for the further development of the space radiation field.