Development of 2.45 GHz Semiconductor Microwave System for Combustion Ignition Enhancement and Failure Analysis

Abstract

We developed a semiconductor microwave system to improve the ignition process in a combustion system. Under atmospheric pressure conditions, large plasma was successfully ignited by a 2.45 GHz microwave, and it is characterized in comparison with standard spark plug ignition and laser ignition. The size of the microwave power source was also effectively reduced with the minimal size (100 × 60 mm2) that could fit in the palm of a hand. We then prototyped a microwave plug with a diameter of 4 mm, which is smaller than the standard spark plugs for passenger cars. The design and electric field strength are discussed in detail. Combustion experiments were conducted using a motorcycle engine and an actual light vehicle, and significant fuel efficiency improvement was experimentally obtained. We investigated the wear of the plug caused by continuous operation, and efficiently improved the endurance by swinging the resonance frequency between 2.4 and 2.5 GHz. In a passenger car engine experiment using a flat panel igniter, significant fuel efficiency improvement was confirmed. Further failure analysis revealed that the ceramic was severely damaged by a large current surge.

Laser ablation plasma expansion using microwaves

“…The control over the plasma characteristics can be demonstrated by the plasma emissions.Analytical applications using laser-induced breakdown spectroscopy (LIBS) [3][4][5][6][7][8][9][10][11][12][13] have proven to be a powerful tool in science and industry. The amount of plasma emission can vary greatly depending on the environmental conditions under which the plasma is generated, and its properties can be controlled for a range of applications such as low-pressure semiconductor manufacturing equipment 14,15 , space applications in a vacuum, elemental analysis [16][17][18] , high-pressure internal combustion engines 19 , and deep-sea applications 20 . However, ablation plasmas are typically limited in their expansion due to system constraints, such as volume size change and plasma lifetime 21 , limitations that are being addressed by microwave-enhanced LIBS by combining microwaves and pulsed lasers resulting in a significantly improved performance of the system [21][22][23][24][25][26][27][28][29][30][31][32] .…”

“…However, ablation plasmas are typically limited in their expansion due to system constraints, such as volume size change and plasma lifetime 21 , limitations that are being addressed by microwave-enhanced LIBS by combining microwaves and pulsed lasers resulting in a significantly improved performance of the system [21][22][23][24][25][26][27][28][29][30][31][32] . The emission intensity of the plasma is significantly enhanced by microwave superposition because microwave energy can sustain the plasma for a much longer period, allowing for more emission events to occur 15,22,31,[33][34][35][36][37][38][39][40][41][42][43][44][45][46] . In addition, the spatial volume of the plasma is expanded by two orders of magnitude, which further increases the amount of light emitted and detected by the system.…”