| Paper | Title | Page |
|---|---|---|
| MOPCH058 | RF Photogun as Ultra Bright Terahertz Source | 0 |
|
||
| 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 |
|
||
| 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. | ||
| TUPCH113 | Construction of the ALPHA-X Photo-injector Cavity | 1277 |
|
||
| We will describe the construction and low power testing of an RF cavity to be used as a photo-injector for the ALPHA-X project within the Department of Physics at the University of Strathclyde (UK). The gun is a two and a half cell S-band cavity, employing a metallic photo-cathode. RF power is coupled to the gun via a co-axial power coupler. The specification of the gun and the low power measurements made to achieve the correct mode frequency and field flatness will be presented. | ||
| WEPLS024 | Linear Laser Wakefield Acceleration with External Injection | 0 |
|
||
| The Laser Wakefield project at Eindhoven University seeks to separate three processes needed for controlled LWFA: Creation of a plasma channel, injection of electrons and acceleration of these electrons. This enables control over and optimization of the individual components of the accelerator. It also removes the need to operate in the non-linear wakefield regime. This allows the use of lower density plasma regimes without requiring enormous laser intensities. Using front-to-end particle tracking simulations, a setup has been designed consisting of a RF-photogun, a 'modest' 2 TW tabletop laser and a pulsed capillary discharge plasma. Together, these enable the creation of 100 MeV, 1pC bunches with a duration of 10fs. The capabilities of the setup under construction will be presented. Also the outlook of laser wakefield acceleration with external injection will be discussed. | ||
| WEPLS033 | Cold Atom Electron Sources | 0 |
|
||
|
We are developing a completely new method of producing high-brightness electron bunches, based on extraction of electrons from an ultra-cold plasma, created by photo-ionization of a cloud of laser-cooled atoms*. In this way extremely low thermal emittances (<0.1 micron) can be reached at bunch charges of several pC. In addition, pulsed extraction leads to fs bunch lengths and tens of A peak currents without the use of ultra-fast lasers or magnetic compression. GPT simulations in realistic settings show that orders of magnitude in beam brightness may be gained compared to state-of-the-art rf photoguns. Experiments are underway, whose status will be reported.
*B. J. Claessens et al. Phys. Rev. Lett. 95, 164801 (2005). |