Theoretical and Experimental Discourse on Laser Ignition in Liquid Rocket Engines

Igniter technologies have seen an increased interest in the past decades due to the increasing re-ignition needs, such as for the upper stage Vinci engine. Weight reduction considerations and redundancy considerations have lead to an increased number of studies in alternative igniter technologies to the conventional pyrotechnical or spark plug igniters in use today. Such technologies include concepts such as resonance igniters, catalyst igniters and laser igniters. When compared to classical ignition methods, both in the automotive industry, i.e. spark ignition, and in the space industry, i.e. pyrotechnic/torch ignition, laser ignition system (LIS) offer multiple advantages. Literature classifies laser-gas interactions into four main categories which differ in the mechanisms leading to ignition: non-resonant breakdown ignition, resonant breakdown ignition, thermal ignition and photochemical ignition. Non-resonant laser ignition is the most common form of ignition and involves a well-focused pulsed laser beam thus creating a well localized plasma which can accumulate further energy leading to a local increase in temperature and finally ignition. Non-resonant laser ignition may occur via either a multiphoton ionization process or an electron cascade process. This paper addresses the main issues related with the various laser ignition methods via a literature review of research conducted in the field of laser ignition. The main findings of the experimental work done in the non-resonant laser ignition of a coaxial liquid oxygen and gaseous methane jet at the DLR Lampoldshausen M3.1 test bench is presented

International Space Exploration Coordination Group Assessment of Technology Gaps for LOx/Methane Propulsion Systems for the Global Exploration Roadmap

As part of the Global Exploration Roadmap (GER), the International Space Exploration Coordination Group (ISECG) formed two technology gap assessment teams to evaluate topic discipline areas that had not been worked at an international level to date. The participating agencies were ASI, CNES, DLR, ESA, JAXA, and NASA. Accordingly, the ISECG Technology Working Group (TWG) recommended two discipline areas based on Critical Technology Needs reflected within the GER Technology Development Map (GTDM): Dust Mitigation and LOX/Methane Propulsion. LOx/Methane propulsion systems are enabling for future human missions Mars by significantly reducing the landed mass of the Mars ascent stage through the use of in-situ propellant production, for improving common fluids for life support, power and propulsion thus allowing for diverse redundancy, for eliminating the corrosive and toxic propellants thereby improving surface operations and reusability, and for increasing the performance of propulsion systems. The goals and objectives of the international team are to determine the gaps in technology that must be closed for LOx/Methane to be used in human exploration missions in cis-lunar, lunar, and Mars mission applications. An emphasis is placed on near term lunar lander applications with extensibility to Mars. Each agency provided a status of the substantial amount of Lox/Methane propulsion system development to date and their inputs on the gaps in the technology that are remaining. The gaps, which are now opportunities for collaboration, are then discussed