Imperial College London

Dr Saleh AlAtabi

Faculty of Natural SciencesDepartment of Physics

Academic Visitor
 
 
 
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Contact

 

+44 (0)20 7594 7643s.alatabi13

 
 
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Location

 

733Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

7 results found

Cole JM, Symes DR, Lopes NC, Wood JC, Poder K, Alatabi S, Botchway SW, Foster PS, Gratton S, Johnson S, Kamperidis C, Kononenko O, De lazzari M, Palmer CAJ, Rusby D, Sanderson J, Sandholzer M, Sarri G, Szoke-Kovacs Z, Teboul L, Thompson JM, Warwick JR, Westerberg H, Hill MA, Norris DP, Mangles SPD, Najmudin Zet al., 2018, High-resolution mu CT of a mouse embryo using a compact laser-driven X-ray betatron source, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 115, Pages: 6335-6340, ISSN: 0027-8424

Journal article

Poder K, Cole JM, Wood JC, Lopes NC, Alatabi S, Foster PS, Kamperidis C, Kononenko O, Palmer CA, Rusby D, Sahai A, Sarri G, Symes DR, Warwick JR, Mangles SPD, Najmudin Zet al., 2017, Measurements of self-guiding of ultrashort laser pulses over long distances, Plasma Physics and Controlled Fusion, Vol: 60, ISSN: 0741-3335

We report on the evaluation of the performance of self-guiding over extended distances with $f/20$ and $f/40$ focussing geometries. Guiding over $39\,\mathrm{mm}$ or more than 100 Rayleigh ranges was observed with the $f/20$ optic at ${n}_{e}=1.5\times {10}^{18}\,{\mathrm{cm}}^{-3}$. Analysis of guiding performance found that the extent of the exiting laser spatial mode closely followed the matched spot size predicted by 3D nonlinear theory. Self-guiding with an $f/40$ optic was also characterised, with guided modes observed for a plasma length of $90\,\mathrm{mm}$ and a plasma density of ${n}_{e}=9.5\times {10}^{17}\,{\mathrm{cm}}^{-3}$. This corresponds to self-guided propagation over 53 Rayleigh ranges and is similar to distances obtained with discharge plasma channel guiding.

Journal article

Symes DR, Najmudin Z, Cole JM, Wood JC, Lopes NC, Poder K, Abel P, Abel RL, Alatabi S, Kneip S, Mecseki K, Winkler M, Foster PS, Norris DP, Teboul L, Johnson S, Szoke-Kovacs Z, Sandholzer M, Botchway S, Gratton S, Hill MA, De Lazzari M, Thomson Jet al., 2016, High-resolution tomographic imaging using coherent hard x-rays from compact laser driven accelerators, Compact EUV & X-ray Light Sources 2016, Publisher: OSA Publishing

Extremely bright coherent femtosecond x-ray pulses are generated in compact laserdriven electron accelerators. Micro-tomography obtained with the Gemini laser indicates the usefulness of these sources in research and clinical applications.

Conference paper

Cole JM, Wood JC, Lopes NC, Poder K, Abel RL, Alatabi S, Bryant JSJ, Jin A, Kneip S, Mecseki K, Parker S, Symes DR, Sandholzer MA, Mangles SPD, Najmudin Zet al., 2016, Tomography of human trabecular bone with a laser-wakefield driven x-ray source, Plasma Physics and Controlled Fusion, Vol: 58, ISSN: 1361-6587

A laser-wakefield driven x-ray source is used for the radiography of human bone. The betatron motion of accelerated electrons generates x-rays which are hard (critical energy ${{E}_{\text{crit}}}>30$ keV), have small source size (<3 μm) and high average brightness. The x-rays are generated from a helium gas cell which is near-instantly replenishable, and thus the average photon flux is limited by the repetition rate of the driving laser rather than the breakdown of the x-ray source. A tomograph of a human bone sample was recorded with a resolution down to 50 μm. The photon flux was sufficiently high that a radiograph could be taken with each laser shot, and the fact that x-ray beams were produced on 97% of shots minimised failed shots and facilitated full micro-computed tomography in a reasonable time scale of several hours, limited only by the laser repetition rate. The x-ray imaging beamline length (not including the laser) is shorter than that of a synchrotron source due to the high accelerating fields and small source size. Hence this interesting laboratory-based source may one day bridge the gap between small microfocus x-ray tubes and large synchrotron facilities.

Journal article

Cole JM, Wood J, Lopes NC, Poder K, Abel RL, Alatabi S, Bryant JSJ, Jin A, Kneip S, Mecseki K, Symes DR, Mangles SPD, Najmudin Zet al., 2015, Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone, Scientific Reports, Vol: 5, ISSN: 2045-2322

A bright μm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 μm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications.

Journal article

Appuhamilage IA, Adjei D, Alatabi SS, Alnaimi R, Michette A, Pfauntsch Set al., 2014, Development of a soft X-ray microprobe for radiobiology studies, Pages: 882-885, ISSN: 0587-4246

The King's College London (KCL) first X-ray microprobe (MKI) and the third generation microfocus X-ray sources (MKIII) are intended to be used for various applications including the study of physical and biological interactions at the atomic and molecular scales. The microfocus ultra-soft X-ray sources (MKI and MKIII) with interchangeable targets will provide a superior spatial resolution (a focal spot a few hundreds of nanometres in diameter can be achieved) and the control of the dose delivered to irradiated cells. This will require characterization of the spectra and intensities of the source, measurements of the focus intensities and spot sizes of suitable X-ray optics such as zone plates, grazing incidence microstructured optical arrays and multilayer mirrors.

Conference paper

Alnaimi R, Adjei D, Alatabi S, Appuhamilage IA, Michette Aet al., 2013, King's college laser plasma X-ray source design, ISSN: 0277-786X

The aim of this work is to design and build a source for a range of applications, with optimized multilayer structures in order to use the source output as efficiently as possible. The source is built around a Nd:YAG laser with fundamental wavelength 1064 nm, frequency doubled 532 nm (green) and tripled 355 nm, with a pulse length of about 800 ps and a repetition rate up to 50 Hz. The target material is Mylar (C10H8O4) tape, which is cheap, readily available and has many benefits as explained in this article. A versatile cubic target chamber and a set of computer controlled stage motors are used to allow positioning of the X-ray emission point. A range of measures is used to protect delicate components and optics, including a glass slide between the focusing lens and the target to prevent the lens being coated with debris. A low pressure gas (typically 3-6 mbar) is used inside the chamber as collision of atomic size debris particles with gas molecules reduces their kinetic energy and consequently their adhesion to the surrounding surfaces. The gas used is typically helium or nitrogen, the latter also acting as a spectral filter. Finally, the chamber is continually pumped to ensure that more than 70% of the debris particles are pumped out of the chamber. © 2013 SPIE.

Conference paper

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