Plasma Fibre Using Bright-core Helicon Plasma Demonstrates Wave-guide Feature with Total Reflection of Electromagnetic Waves

Researchers are exploring new ways to transmit information using plasmas, and a team led by Lei Chang and Zi-Chen Kan from Chongqing University now demonstrates a novel concept called a “plasma fibre”. Inspired by optical fibres, this research establishes the theoretical basis and experimental potential for guiding electromagnetic waves within a bright-core helicon plasma, effectively creating a dynamic and reconfigurable channel for signal transmission. Jing-Jing Ma, alongside Saikat Chakraborty Thakur from Auburn University and Juan Francisco Caneses from CompX, contribute to this work which shows that total reflection of electromagnetic waves occurs within the plasma under specific conditions, enabling wave-guiding behaviour. This achievement represents a significant step towards integrating plasma-based components into existing communication systems, offering possibilities for specialised applications and adaptable signal pathways.

Theoretical analyses explore the behaviour of electromagnetic waves near sharp plasma density gradients, specifically in relation to creating a “plasma fibre” analogous to optical fibres. Investigations cover both an ideal case featuring a step-like density profile and a more realistic case with a Gaussian density profile in radius. The total reflection of electromagnetic waves and the resulting wave-guide feature occur when the incident angle exceeds a specific threshold value. Numerical computations, performed using an electromagnetic solver based on Maxwell’s equations and the cold-plasma dielectric tensor, yield results consistent with the theoretical predictions. The potential for experimental verification and the incorporation of this “plasma fibre” as a functional component within existing communication systems are also suggested.

Plasma Fibre Wave Guidance Demonstrated

Scientists have introduced the concept of a plasma fibre, drawing a parallel to optical fibres, using bright-core helicon plasma. This research establishes the theoretical foundation and computational verification for guiding electromagnetic waves within a high-density plasma column. Researchers investigated both idealized step-like and realistic Gaussian density profiles to understand wave propagation characteristics. The team discovered that total internal reflection of electromagnetic waves occurs when the incident angle exceeds a specific threshold, a phenomenon crucial for wave-guiding functionality.

This total reflection is directly proportional to the square root of the plasma density ratio between the core and exterior regions, a relationship confirmed through detailed calculations. Numerical simulations, based on Maxwell’s equations and the cold-plasma dielectric tensor, consistently support these findings. For more realistic, continuous density profiles, the team developed a mathematical model to account for the gradual change in refractive index, accurately predicting wave paths as they refract through the plasma. Further analysis suggests the potential for self-focusing and phase distortion correction, mirroring the behaviour of optical fibres. This research establishes a pathway for embedding plasma fibres into existing communication systems, offering dynamic reconfiguration capabilities and opening new possibilities for specialized applications.

Plasma Fibres Guide Waves Like Optics

This work demonstrates the existence of a “plasma fibre”, a novel electromagnetic waveguide sustained by plasma density gradients within a bright-core helicon plasma. Through theoretical analysis and electromagnetic simulations grounded in Maxwell’s equations, researchers established that these plasmas, possessing steep radial density gradients, exhibit total internal reflection and waveguide characteristics analogous to those found in optical fibres. Investigations of both idealized and realistic density profiles reveal frequency-dependent propagation windows and cut-off behaviour, confirming the potential for guided-wave modes within the plasma. This frequency dependence arises from the interplay between plasma density and the wavelength of the electromagnetic waves.

These findings offer a new understanding of wave propagation in bright-core helicon plasmas and suggest potential applications as dynamically reconfigurable waveguides in communication or diagnostic systems. The research represents a conceptual advance that connects plasma physics and photonics, potentially broadening interest across related fields. The authors propose a diagnostic approach using B-dot and Langmuir probes, alongside optical imaging and emission spectroscopy, to map wave propagation and confirm the predicted frequency-selective confinement. Such experiments would directly validate the “plasma fibre” concept and bridge the theoretical and numerical results presented.