Particle accelerators have reached the sustainability limit in terms of investment and operation costs versus scientific outcome and large
The aim is to stimulate charge density ripples along the CNTs by high-frequency electric fields taking benefit of the large axial electrical conductivity. This can be achieved by either irradiating the target with laser pulses or electron bunches. Charge density fluctuations leave the carbon atoms unbalanced electrically and, in consequence, large electric fields are expected to be generated. Their appearance has been already demonstrated when dopped CNTs irradiated by laser pulses of 10 - 20 fs length and 1017 - 1018 W/cm2 intensity released 1.5MeV protons [9]. A key part of this proposal is the optimization of these electric fields in terms of amplitude and periodicity, such that they can be used for particle acceleration and possibly focusing of a witness particle bunch.
The research and development work is split in two major stages: (1) numerical simulations and (2) proof-of-principle experiment. The first stage requires sophisticated particle-in-cell codes (PIC) such as PIConGPU [10], EPOCH [11] and OSIRIS [12]. As a preliminary milestone, the interaction of electron bunches and laser pulses with two-dimensional charge density ribbons will be studied. Though not completely realistic, due to the low memory and processing power overhead, such a setup enables a quick optimization of the main parameters: wavelength, spot size, length, polarization and power for the laser pulse and energy, emittance, and current for the driving electron bunch. After defining the parameters ranges and boundary conditions, three-dimensional PIC studies will be carried out. This will include modelling the CNTs as granular charge density tubes. Following a refined parametric optimization, acceleration of witness bunches will be attempted numerically. Eventually these simulations will guide the design of a proof-of-principle experiment, depending on available electron sources and CNTs manufacturers. The experimental work including data acquisition and processing will complete the second stage of this research and development project.
A positive outcome of the project may stimulate further research in solid-state acceleration mechanisms for which a community already exists. It could open the possibility to create small-scale and cost-effective accelerators for fundamental scientific and medical research.
Student: Cristian Bontoiu
References
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