Plasma Lens Experiment Research Articles

Tapering of plasma density ramp profiles for adiabatic lens experiments

One of the key elements of the plasma wakefield blowout regime is the strong, linear focusing provided by the ion density. One advantage of this focusing is its extraordinary strength whose gradient is proportional to the local background plasma density, that is particularly important for adiabatic focusing schemes in future compact linear colliders. Local plasma density variations can be obtained in gas-filled capillaries by varying monotonically the diameter of the capillary. Here we present the ongoing study of the plasma density profile obtained for different tapering angles of the capillary shape and we discuss their use for the adiabatic plasma lens experiment proposed at SPARC_LAB.

Adiabatic plasma lens experiments at SPARC

Passive plasma lenses in the underdense regime have been shown to give extremely strong linear focusing, with strength proportional to the local plasma ion density. This technique has been proposed as the basis of a scheme for future linear colliders that mitigates the Oide effect through adiabatic focusing. In this scenario the plasma density in the lens is ramped slowly on the scale of betatron motion, to funnel the beam to its final focus while forgiving chromatic aberrations. We present to the physics design of an adiabatic plasma lens experiment to be performed at SPARC Lab. We illustrate the self-consistent plasma response and associated beam optics for symmetric beams in plasma, simulated by QuickPIC using exponentially rising density profiles. We discuss experimental plans including plasma source development and betatron-radiation-based beam diagnostics.

Overview of plasma lens experiments and recent results at SPARC_LAB

Beam injection and extraction from a plasma module is still one of the crucial aspects to solve in order to produce high quality electron beams with a plasma accelerator. Proper matching conditions require to focus the incoming high brightness beam down to few microns size and to capture a high divergent beam at the exit without loss of beam quality. Plasma-based lenses have proven to provide focusing gradients of the order of kT/m with radially symmetric focusing thus promising compact and affordable alternative to permanent magnets in the design of transport lines. In this paper an overview of recent experiments and future perspectives of plasma lenses is reported.

Overview of the CLEAR plasma lens experiment

Discharge capillary-based active plasma lenses are a promising new technology for strongly focusing charged particle beams, especially when combined with novel high gradient acceleration methods. Still, many questions remain concerning such lenses, including their transverse field uniformity, limitations due to plasma wakefields and whether they can be combined in multi-lens lattices in a way to cancel chromaticity. These questions will be addressed in a new plasma lens experiment at the CLEAR User Facility at CERN. All the subsystems have been constructed, tested and integrated into the CLEAR beam line, and are ready for experiments starting late 2017.

Simulation studies of plasma lens experiments at Daresbury laboratory

Experiments are planned to study plasma lensing using the VELA and CLARA Front End accelerators at Daresbury Laboratory. This paper presents results of 2-dimensional particle-in-cell simulations of the proposed experiments. The variation in focusing strength and emittance growth with beam and plasma parameters are studied in the overdense (plasma density much greater than bunch density) regime for the VELA beam. The effect of spherical and longitudinal aberrations on the beam emittance was estimated through numerical and theoretical studies. Simulation results show that a focusing strength equivalent to a magnetic field gradient of 10 T m−1 can be achieved using VELA, and a gradient of 247 T m−1 can be achieved using CLARA Front End.

A monitor of the focusing strength of plasma lenses using MeV synchrotron radiation

The focusing strength of plasma lenses used with high energy electron or positron beams can give rise to synchrotron radiation with critical energies in the MeV range. A method is described for measuring the characteristic energy of this radiation as a way of monitoring the strength of the focus. The principle has been implemented in a plasma lens experiment with a 28.5 GeV positron beam.

Plasma source test and simulation results for the underdense plasma lens experiment at the UCLA Neptune Laboratory

The planned plasma lens experiment at the UCLA Neptune Laboratory is described. In the experiment, electron beams with an energy of 16 MeV, a charge of 4 nC, and a pulse duration of 30 ps [full-width at half-maximum (FWHM)] are designed to be produced from the 1.625-cell photoinjector radio-frequency gun (f=2.856 GHz) and PWT linac in the Neptune. The generated beams are passed through a thin plasma with a density of low 10/sup 12/ cm/sup -3/ range and a thickness of a few centimeters. For this experiment, a LaB/sub 6/-based discharge plasma source was developed and tested. In this paper, the overview of the planned plasma lens experiment and the test results of the plasma source for various conditions are presented. In addition, computer simulations with a 2-1/2 dimensional particle-in-cell code (MAGIC) were performed and the simulation results are shown.

Plasma lens experiment at the final focus test beam

The proposed plasma lens experiment at the Final focus Test Beam (FFTB) facility of the Stanford Linear Accelerator Center (Chen et al. SLAC, 1997) [1]has been approved by the adminstration. The experiment would allow the examination of plasma focusing devices for particle beams in the parameter regime of interest to future high-energy colliders. It is expected to lead to compact plasma lens designs capable of focusing the beam to unprecedented small spot sizes.