A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z    

van Oudheusden, T.

Paper Title Page
MOPCH058 RF Photogun as Ultra Bright Terahertz Source 0
 
  • W.P.E.M. Op 't Root, M.J. Loos, O.J. Luiten, M.J. Van der Wiel, T. van Oudheusden, S.B. van der Geer
    TUE, Eindhoven
 
  Recently research into new terahertz (0.3 to 30 THz) light sources has gained a lot of interest. Especially compact sources capable of delivering high peak fields (~ 1 MV/cm), in a short pulse. To achieve this, we will use short relativistic electron bunches, created by photoemission and accelerated in an rf-photogun, to create THz light by means of coherent transition radiation. Because wavelengths smaller and comparable to the bunch length add up coherently, the intensity scales with N2, with N the number of electrons in the bunch. In the first experiments we expect to create THz light pulses with a bandwidth of 1 THz and 1 μJ per pulse. If such a light pulse is focused on a spot of radius 250 μm, this corresponds to peak electrical fields of 1 MV/cm. The eventual goal is to increase the bandwidth of the source, by creating shorter electron bunches. This will be accomplished by choosing a suitable radial laser profile, leading to ellipsoidal electron bunches, which can be focused and compressed very effectively. Eventually this will lead to THz pulses with a bandwidth of 10 THz and energy of 100 μJ. This corresponds to peak electrical fields of 10 MV/cm and higher.  
MOPCH059 From Pancake to Waterbag: Creation of High-brightness Electron Bunches 0
 
  • T. van Oudheusden, O.J. Luiten, W.P.E.M. Op 't Root, M.J. Van der Wiel, S.B. van der Geer
    TUE, Eindhoven
 
  Our recent insight is that, when creating high-brightness electron bunches, the major problem is not space charge density itself, but its distribution. Non-linear space charge effects lead to a decrease of brightness. We have a novel recipe of creating waterbag bunches (uniformly charged 3D ellipsoids), which have linear space charge fields. Because of these linear fields we have control of the Coulomb explosion of the bunches. Furthermore, using linear charged particle optics, waterbags can be compressed and focussed with conservation of brightness. Our recent simulations prove that it is possible to create such ideal waterbag bunches in practice. The recipe is to create at the cathode a pancake-like electron bunch with a "hemisphere" charge density distribution. During acceleration this pancake will evolve into a waterbag by its own space charge forces, if two conditions on the acceleration field and the surface charge density are fulfilled. These two conditions are leading to a parameter space, which is explored by simulations. We will present numerical simulations and the present status of the experimental realization.