Abstract
Braking conditions are a fundamental issue for the railway and have been a limiting factor in network capacity and timetabling. Leaf fall, especially during the autumn season, creates low-adhesion problems on railways, causing braking problems for trains. To address the requirements of the novel plasma industrial applications towards environmental applications, this work developed and tested a 2.45 GHz microwave atmospheric pressure plasma system for in situ removal of the third body layer deposited onto the railway so as to improve braking. The plasma reactor consisted of a 15 kW, 2.45 GHz magnetron-based microwave generator and a plasma reactor (dielectric tube placed in a TE01 monomode microwave cavity); the atmospheric plasma ignited and sustained at different power levels (2–15 kW) in different gases (nitrogen, argon) as well as mixtures of these gases with reactive molecules (water, oxygen) was jetted directly onto the railhead as to change the conditions for the wheel–rail interface. This technology is hoped to be a game-changer in enabling predictable and optimized braking on the railway network. Challenges encountered during the demonstration phase are discussed. Subsequent work should validate the results on a working railway line during the autumn season.
Highlights
The interface between the wheel and the rail is a specialist subject with continual research being done
A gasHowever, discharge microwave plasma source can be at thetoengineering level, in many sustained by an electromagnetic field, and the conditions for its maintenance are essentially determined there are some general considerations that are common to all: the plasma results from a gas discharge by the charged and energy lossand mechanism
The results show a higher performance of the microwave plasmas compared to direct current (DC) plasma at similar conditions of power delivered to the rail (British Rail Research was conducted at 16 kW)
Summary
The interface between the wheel and the rail is a specialist subject with continual research being done. Effective railway acceleration and braking is reliant on the small contact patch between wheel and rail, known as the wheel–rail interface; this is roughly 1 cm and must support high loads under numerous different conditions. Some of the causes of low adhesion in the wheel–rail contact are well understood and can be predicted and mitigated, whilst others remain hard to prevent. Different environmental conditions such as temperature, precipitation and humidity change the properties of this third body layer and change adhesion conditions on the railway [1,2,3]
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