Compression and microbunching of electron beams by ultra-intense laser pulses

The formation of coherent structures, induced by a super-intense plane electromagnetic wave with a sharp rising edge in an ensemble of electrons (electron beam) in vacuum, is considered. The theory describing this process is elaborated. It is shown that the laser pulse can strongly compress the electron beam and also generate fast density modulations (microbunching) in it. Depending on the duration of a laser pulse front, two harmonics can be present simultaneously in longitudinal density modulations of the electron beam-one with laser wavelength and the other with half of the laser wavelength. By changing the form of the laser pulse envelope, one can control the average density of the electron beam (slow density modulation). By varying the laser pulse amplitude and initial length of the electron beam, it is possible to change the number of microbunches in the compressed electron beam, and for certain conditions only one electron bunch can be produced with ultrashort length smaller than the laser wavelength (attosecond length electron beam). The results of the theory are compared with 1D PIC (particle-in-cell) simulations and a good agreement is found.close4

Bunching of electron beams by ultra-relativistic laser pulses

The bunching of an electron beam by an ultra-relativistic laser pulse in vacuum is considered. The one-dimensional theory describing this process is elaborated. The laser pulse is shown to compress the electron beam and to generate fast density modulations (microbunching) in it. Two spatial harmonics can be present simultaneously in longitudinal density modulations of the electron beam - one with the laser wavelength and the other with half of the laser wavelength, and the ratio of the amplitudes of the harmonics depends on the duration of the laser pulse front. The average density of the electron beam (slow density modulation) can be controlled by changing the form of the laser pulse envelope. The number of microbunches in the compressed electron beam can be changed by varying the amplitude of the laser pulse and the initial length of the electron beam, and for certain conditions, only one electron bunch with an attosecond length can be produced. The results of the theory are compared with 1D PIC (Particle-In-Cell) simulations, and a good agreement is found.open4

Relativistic electron mirrors from nanoscale foils for coherent frequency upshift to the extreme ultraviolet

Reflecting light from a mirror moving close to the speed of light has been envisioned as a route towards producing bright X-ray pulses since Einstein’s seminal work on special relativity. For an ideal relativistic mirror, the peak power of the reflected radiation can substantially exceed that of the incident radiation due to the increase in photon energy and accompanying temporal compression. Here we demonstrate for the first time that dense relativistic electron mirrors can be created from the interaction of a high-intensity laser pulse with a freestanding, nanometre-scale thin foil. The mirror structures are shown to shift the frequency of a counter-propagating laser pulse coherently from the infrared to the extreme ultraviolet with an efficiency >10(4) times higher than in the case of incoherent scattering. Our results elucidate the reflection process of laser-generated electron mirrors and give clear guidance for future developments of a relativistic mirror structure

Detection of paroxysmal nocturnal hemoglobinuria-phenotype in patients with chronic lymphocytic leukemia and multiple myeloma

Background : Paroxysmal nocturnal hemoglobinuria (PNH) results due to decrease or absence of glycosylphosphatidylinositol-anchored (GPI) molecules, such as CD55 and CD59, from the surface of the affected cells. PNH-phenotype has been described in various hematological disorders, mainly aplastic anemia and myelodysplastic syndromes; recently it has been reported in patients with lymphoproliferative syndromes and multiple myeloma (MM). Materials and Methods : We evaluated the presence of CD55 negative and/or CD59 negative red blood cell (RBC) populations in newly diagnosed treatment naive-54 chronic lymphocytic leukemia (CLL) and 29 MM patients by flow cytometry. Results : PNH-phenotype was not reported in any patient; however, RBC populations deficient in CD55 were detected in 16.66% (9/54) CLL and 6.89% (2/29) MM patients. Clinical presentation or the hematological parameters did not show any relationship with the presence of CD55 deficient RBC population. Conclusion : Our study showed absence of PNH-phenotype in patients with CLL and MM; however, isolated CD55 deficient RBC were identified in both CLL and MM. Larger prospective studies by other centers, including simultaneous analysis of granulocytes for the presence of PNH-phenotype, are needed to corroborate these findings and to work out the mechanisms and the significance of the existence of this phenotype in these patients