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Modern day propulsion systems are used in aerospace applications for different
purposes. The aerospace industry typically requires propulsion systems to operate in a rocket
mode in order to drive large boost vehicles. The defense industry generally requires propulsion
systems to operate in an air-breathing mode in order to drive missiles. A mixed system could
use an air-breathing first stage and a rocket-mode upper stage for space access. Thus, propulsion
systems can be used for high mass payloads and where the payload is dominated by the
fuel/oxidizer mass being used by the propulsion system. The pulse detonation wave engine
(PDWE) uses an alternative type of detonation cycle to achieve the same propulsion results.
The primary component of the PDWE is the combustion chamber (or detonation tube). The
PDWE represents an attractive propulsion source since its engine cycle is thermodynamically
closest to that of a constant volume reaction. This characteristic leads to the inference that a
maximum of the potential energy of the PDWE is put into thrust and not into flow work.
Consequently, the volume must be increased. The technical community has increasingly
adopted the alternative choice of increasing total volume by designing the engine to include a
set of banks of smaller combustion chambers. This technique increases the complexity of the
ignition subsystem because the inter-chamber timing must be considered.
Current approaches to igniting the PDWE have involved separate shock or blast wave
initiators and chemical additives designed to enhance detonatibility. An optical ignition
subsystem generates a series of optical pulses, where the optical pulses ignite the fuel/oxidizer
mixture such that the chambers detonate in a desired order. The detonation system also has an
optical transport subsystem for transporting the optical pulses from the optical ignition
subsystem to the chambers. The use of optical ignition and transport provides a non-toxic,
small, lightweight, precisely controlled detonation system.
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