Tunable High Spatio-Spectral Purity Undulator Radiation from a Transported Laser Plasma Accelerated Electron Beam.

Undulator based synchrotron light sources and Free Electron Lasers (FELs) are valuable modern probes of matter with high temporal and spatial resolution. Laser Plasma Accelerators (LPAs), delivering GeV electron beams in few centimeters, are good candidates for future compact light sources. However the barriers set by the large energy spread, divergence and shot-to-shot fluctuations require a specific transport line, to shape the electron beam phase space for achieving ultrashort undulator synchrotron radiation suitable for users and even for achieving FEL amplification. Proof-of-principle LPA based undulator emission, with strong electron focusing or transport, does not yet exhibit the full specific radiation properties. We report on the generation of undulator radiation with an LPA beam based manipulation in a dedicated transport line with versatile properties. After evidencing the specific spatio-spectral signature, we tune the resonant wavelength within 200-300 nm by modification of the electron beam energy and the undulator field. We achieve a wavelength stability of 2.6%. We demonstrate that we can control the spatio-spectral purity and spectral brightness by reducing the energy range inside the chicane. We have also observed the second harmonic emission of the undulator.

Publisher Correction: Control of laser plasma accelerated electrons for light sources.

The original version of this Article contained an error in the last sentence of the first paragraph of the Introduction and incorrectly read 'A proper electron beam control is one of the main challenges towards the Graal of developing a compact alternative of X-ray free-electron lasers by coupling LWFA gigaelectron-volts per centimetre acceleration gradient with undulators in the amplification regime in equation 11, nx(n-ß) x ß: n the two times and beta the two times should be bold since they are vectorsin Eq. 12, ß should be bold as well.' The correct version is 'A proper electron beam control is one of the main challenges towards the Graal of developing a compact alternative of X-ray free-electron lasers by coupling LWFA gigaelectron-volts per centimetre acceleration gradient with undulators in the amplification regime.'This has been corrected in both the PDF and HTML versions of the Article.

Control of laser plasma accelerated electrons for light sources.

With gigaelectron-volts per centimetre energy gains and femtosecond electron beams, laser wakefield acceleration (LWFA) is a promising candidate for applications, such as ultrafast electron diffraction, multistaged colliders and radiation sources (betatron, compton, undulator, free electron laser). However, for some of these applications, the beam performance, for example, energy spread, divergence and shot-to-shot fluctuations, need a drastic improvement. Here, we show that, using a dedicated transport line, we can mitigate these initial weaknesses. We demonstrate that we can manipulate the beam longitudinal and transverse phase-space of the presently available LWFA beams. Indeed, we separately correct orbit mis-steerings and minimise dispersion thanks to specially designed variable strength quadrupoles, and select the useful energy range passing through a slit in a magnetic chicane. Therefore, this matched electron beam leads to the successful observation of undulator synchrotron radiation after an 8 m transport path. These results pave the way to applications demanding in terms of beam quality.

Ultrashort pulsed neutron source.

We report on a novel compact laser-driven neutron source with an unprecedented short pulse duration (<50 ps) and high peak flux (>10(18) n/cm(2)/s), an order of magnitude higher than any existing source. In our experiments, high-energy electron jets are generated from thin (<3 µm) plastic targets irradiated by a petawatt laser. These intense electron beams are employed to generate neutrons from a metal converter. Our method opens venues for enhancing neutron radiography contrast and for creating astrophysical conditions of heavy element synthesis in the laboratory.

Comparative study of isradipine and sodium nitroprusside in the control of hypertension in patients following coronary artery-bypass surgery.

Essential hypertension is a common occurrence after coronary artery bypass-graft surgery. CABG and may lead to postoperative complications. In an open randomized study, either isradipine or sodium nitroprusside was given by infusion to 27 postoperative CABG patients who had a mean arterial pressure (MAP) greater than 100 mmHg. Both agents were able to achieve reductions in MAP to 80-90 mmHg quickly and safely, although the effects of isradipine at the dosage used were apparent sooner and gave smoother control than with sodium nitroprusside. There were two non-responders with the latter agent. Systemic vascular resistance fell and cardiac output increased in patients in both treatment groups. Also, an increase in heart rate was observed with both agents, although this increase was smaller with isradipine. In conclusion, isradipine appears to be a useful agent in the treatment of hypertension following CABG surgery and may have some advantages over sodium nitroprusside.

Isradipine, a calcium antagonist, in the control of hypertension following coronary artery-bypass surgery.

Arterial hypertension is common after coronary artery-bypass grafting (CABG) surgery and may lead to postoperative complications. Therefore, the effects of the calcium antagonist isradipine were studied in 10 postoperative CABG patients who had a mean arterial pressure (MAP) above 100 mm Hg. Isradipine, given as a continuous infusion, reduced MAP to the range of 85 +/- 5 mm Hg in all patients within 15 min. Systemic vascular resistance fell and cardiac output increased in all patients. A slight increase in heart rate was seen in some, but not all, patients. There were no adverse effects. In conclusion, isradipine appears to be a useful agent in the treatment of postoperative hypertension following CABG surgery.