Particle and x-ray generation by irradiation of gaseous and solid targets with a 100TW laser pulse Oswald Willi Heinrich-Heine University, Düsseldorf Germany 36th EPS Conference on Plasma Physics th EPS Conference on Plasma Physics 2009 Sofia 29. June 2009

Arbeitsplan für den Projektzeitraum Januar - Dezember 2009 Contributors M. Behmke, L. Gezici, B. Hidding, R. Jung, T. Königstein, A. Pipahl, J. Osterholz, G. Pretzler, A. Pukhov, M. Toncian, T. Toncian Institute of Laser- and Plasma-Physics, Heinrich-Heine University, Düsseldorf, Germany Institute of Optics and Quantum Electronics, Friedrich Schiller University Jena, Germany Institute of Nuclear Physics, Research Centre Jülich, Germany M. Heyer, O. Jäckel, M. Kübel, G. Paulus, C. Rödel, H.P. Schlenvoigt, W. Ziegler M. Büscher, A. Feyt, A. Lehrach, H. Ohm, G. Oswald, N. Raab, M. Ruzzo, M. Seltmann, Q. Zhang

Outline 100TW Laser System Experimental studies Experimental infrastructure Ionization dynamics and channel development in Helium Quasi-monoenergetic electron acceleration MeV proton spectra on thin foil targets High Harmonic generation from solid targets

0.5 TW The Düsseldorf 100 TW laser Oscillator (Femto) Booster (~10 4 gain) Booster (~10 4 gain) Grating Stretcher (~ 600 ps) Grating Stretcher (~ 600 ps) Regenerative Amplifier Power Amplifier 1 Power Amplifier 2 Power Amplifier 3 (beam 2) Power Amplifier 3 (beam 2) 15J 2 J Power Amplifier 3 (beam 1) Power Amplifier 3 (beam 1) 8 J Air Compressor Vac. Compr. 100TW Vac. Compr. 100TW Vac. Compr. 200TW Vac. Compr. 200TW 20 fs, 75 MHz 5 nJ  J 7 mJ15 mJ  J 1 mJ 30 mJ 15 mJ 300 mJ 6 J 3.2 J 120 mJ 100 nm Bandwidth 80 nm Bandwidth

Contrast of 100 TW laser pulse SEQUOIA measurement of ps contrast (February ps ps ps ps <

Schocks in Gasen bieten aufgrund ihrer Eigenschaften eine ideale Möglichkeit zur Untersuchung fundamentaler Prozesse in Laser-erzeugten Plasmen 27 meters The Laboratory

Schocks in Gasen bieten aufgrund ihrer Eigenschaften eine ideale Möglichkeit zur Untersuchung fundamentaler Prozesse in Laser-erzeugten Plasmen 27 meters The Laboratory Laser Vacuum compressor Target chambers Radiation protection Adaptive optics Pump lasers

Schocks in Gasen bieten aufgrund ihrer Eigenschaften eine ideale Möglichkeit zur Untersuchung fundamentaler Prozesse in Laser-erzeugten Plasmen 27 meters The Laboratory Probe beam line Air compressor & delay line

Schocks in Gasen bieten aufgrund ihrer Eigenschaften eine ideale Möglichkeit zur Untersuchung fundamentaler Prozesse in Laser-erzeugten Plasmen 27 meters The Laboratory 2nd main beam line Compressor Amplifier & delay line

Schocks in Gasen bieten aufgrund ihrer Eigenschaften eine ideale Möglichkeit zur Untersuchung fundamentaler Prozesse in Laser-erzeugten Plasmen 27 meters The Laboratory December 2009

Numerous diagnostics have been installed already to ensure optimal experimental conditions Online measurement of pulse energy and spectrum 3 rd order autocorrelation contrast measurement using SEQUOIA Pulse duration and shape resolved using SPIDER-technique (APE) SPIDER-signal from target chamber is used to optimize MAZZLER settings in order to control of pulse duration Full pulse-train control allows single-shot to 10-Hz application Laser and delay-lines fully computer controlled Target chamber for laser-gas interaction Adaptive mirror allows phase-front corrections Computer-controlled polarizer attenuator allows to vary the pulse energy continuously and to optimize the focus under full energy condition

Arbeitsplan für den Projektzeitraum Januar - Dezember 2009 Pump (25 fs) Probe (30 fs) High density gas jet Variable 30 fs probe pulse at 2   Shadowgraphy, interferometry and Schlieren technique applied Optical probing of plasma development in Helium induced by Düsseldorf 100-TW-Laser

1,5 mm Laser pulseElectrons Gas jet Electron energies up to 180 MeV have been observed Ionization is accompanied by rapid filamentation Shadowgram of plasma produced t = 3.5 ps

Optical probing of plasma development in Helium induced by Düsseldorf 100-TW-Laser 1,5 mm Laser pulseElectrons Gas jet Spectroscopy of light emission from channel axis perfomed Outer filaments and inner channel clearly resolved Shadowgram of plasma produced t = 83 ps t = 3.5 ps

Optical probing of plasma development in Helium induced by Düsseldorf 100-TW-Laser 1,5 mm Laser pulseElectrons Gas jet Shadowgram of plasma produced Structures are in good agreement with 2D-PIC simulations density profile Consequences on absorp- tion and conversion efficiency to be studied

A. Pukhov & J. Meyer-ter-Vehn, Appl. Phys. B74, 355 (2002) Quasi-monoenergetic electron acceleration plasma wavelength < pulse length e-e- (a 0 =5)

Experimental set-up for electron acceleration

Arbeitsplan für den Projektzeitraum Januar - Dezember 2009 Quasi mono-energetic electron spectrum ∞ Electron spectrum for a 40fs, 1.8J laser pulse, I=1.5x10 19 Wcm -2 FWHM = 2.4% Electron energy (MeV) Electron signal (a.u.) The bubble scaling predicts about 180MeV

Arbeitsplan für den Projektzeitraum Januar - Dezember 2009 Control of electron bunch direction with adaptive mirror Beamviewer recordings with an adaptive mirror. The circles denote the spectrometer aperture (5.5mrad).

Arbeitsplan für den Projektzeitraum Januar - Dezember 2009 Quasi-monoenergetic electron bunches have been observed bg corected low energy bunch bg corected high energy bunch Density: 1.1·10 19 /cm³ 60 TW E/MeV E/MeV

Arbeitsplan für den Projektzeitraum Januar - Dezember 2009 Quasi-monoenergetic electron bunches have been observed bg corected low energy bunch bg corected high energy bunch Density: 1.1·10 19 /cm³ 60 TW E/MeV E/MeV Fluorescence signal seen on Lanex screen 70 cm behind the gas jet Divergence <5mrad

Interpretation of spectra Bubble scaling predictions: see Gordienko/Pukhov, PoP 12 (2005) approx. 200 MeV for 60 fs Different scenarios for multi-spikes in spectra: 1. Decay of bubble during/at the end of interaction. Not very pronounced spikes. 2. Laser-triggered plasma wave is so strong, that electrons are also injected in wave bucket BEHIND laser pulse (e.g., see Glinec et al., PRL 98, 2007). 3. Self-modulation of laser bunch, fragmentation, more than one laser bunch fragment triggers bubble acceleration. Leads to especially pronounced spikes in electron spectra. Electron bunches separated by distances of the order of the plasma wavelength (can be only tens of fs with high densities).

MeV proton acceleration on thin foil targets TNSA mechanism thin metal foil target high intensity laser pulse electrons ions are accelerated via space charge (protons take up most of the energy) plasma sheath contamination layer

Proton Acceleration OAP f # =7 Magnetic spectrometer with B=0.5 T Protons up to 5 MeV from 0.5 µm Al I=5x10 18 W/cm 2

Thickness scaling experiments show a very high laser contrast multi-fs simulations predicts ns-contrast < Experiment 1D PIC

The Relativistic Oscillating Mirror model (ROM-harmonics) The relativistic laser pulse leads to anharmonic oscillations of the critical surface (“the mirror”) In the reflected pulse train, ultra-short harmonics are expected Roll-over: Phase modulation by oscillating mirror: Figure by Ch. Rödel et al. n>8 1/2  3 T. Baeva et al, PRE 74, (2006)

Experimental setup at Düsseldorf Figure by Ch. Rödel et al.

CWE-harmonics with and without plasma mirror using the Düsseldorf laser Laser intensity Without PM photons or 0,1 pJ in the 16 th harmonic measured With PM photons or 0,4 pJ in the 16 th harmonic measured Much more reliable signal observed with PM

First observations of ROM-harmonics without plasma mirror seen using the Düsseldorf laser Signal seen without plasma mirror at laser intensity of Without saturable absorber behind in the regenerative amplifier photon or 1 pJ in 29 th harmonic measured Traces up to the Aluminium edge at 17 nm

Relativistic surface harmonics have been observed even without plasma mirror Proof for high contrast of laser pulse Lineouts at different light block positions - SiO 2 light block

2D PIC simulation for HHG generation Electric Field Electron Density

2D PIC simulations for HHG generation x Very complex time structure up to 40   for /10  profile 

Summary Quasi-monoenergetic electron bunches up to ~ 200 MeV have been observed using supersonic gas targets MeV proton spectra observed from 300 nm foil Surface harmonics observed without plasma mirror First experiments within the test period of the Düsseldorf laser in the regime a 0 ~ 2 … 8 Ionization dynamics and channel development in Helium measured using optical probing