Exploring light scattering on dusty plasmas to improve color management in white LEDs

The market share of Light Emitting Diodes (LEDs) in the lighting world is growing quickly (4% in 2013 to an expected 74% in 2030), mainly due to the high energy efficiency compared with traditional lamps. However, the white light which is produced by LEDs does not have the same color temperature as is produced by (for example) incandescent lamps which are perfect black body radiators. Blue light from the LED propagates through a slab of scattering material, where phosphor particles convert the light to different wavelengths, composing white light. To study the extremely complex scatter process inside this phosphor layer, a cloud of negatively charged dust particles being confined inside a plasma is used as a dynamic scatter sample. Due to this negative charge, dust particles are being confined by the electrostatic field in the plasma sheath at the border of the discharge. By changing the plasma parameters, particle cloud properties like density and configuration can be controlled carefully. Hence, utilization of a dusty plasma to study scattering of light has the advantage that properties of the sample can be changed I) in-situ and II) by just turning a knob. A sophisticated setup is designed and developed, allowing spectroscopic measurements at 360◦ around the dust cloud. The functionalities of this setup will be presented, along with preliminary measurements and upcoming research plans.