Researchers from CSU’s Center for Laser Sensing and Diagnostics make Important Advance in Laser Ignition

CSU’s Center for Laser Sensing and Diagnostics (CLSD) has made a significant contribution to the field of laser ignition of engines by developing a new technique based on combining two laser pulses with different wavelengths. The approach has the potential to provide more efficient and cleaner combustion for both stationary and vehicular engines. The findings were recently published in the prestigious journal, Nature – Scientific Reports, which should provide high visibility for the work.

In the combustion field, major emphasis has been placed on developing innovative approaches for cold and lean burn combustion. The CLSD saw the need for an improvement and strategized a method to innovatively utilize laser ignition to further advance the field.

Professor Azer Yalin (right) and Dr. Ciprian Dumitrache (left) inside the CSU’s Center for Laser Sensing and Diagnostics.

As a starting point, the team focused on the idea of using laser generated sparks as an alternative source of ignition, a topic that has been significantly researched in the last 20 years; however, this study took it a step further and introduced a novel technique based on the overlap of two laser pulses that operate a different wavelengths, one ultraviolet and one near-infrared.  Combining the wavelengths allows for a superior ignition source due to fundamental differences in laser plasma formation, ensuing flow-fields and combustion. The results show promise for practical combustion devices including stationary gas engines, aero-turbines, and potentially scramjet engines and rockets.

The research was performed by Professor Azer Yalin and his CLSD research team based at the Powerhouse Energy Institute at CSU. The research group specializes in developing laser sensors and diagnostics for atmospheric science, combustion and plasma applications and has received funding from industry as well as diverse agencies including NSF, DOE, USDA, and the Air Force.

Ciprian Dumitrache, formerly a Ph.D. student in the group and currently a postdoctoral fellow, was very instrumental in the research. During his studies at CSU, Dumitrache was awarded the prestigious “Gordon C. Oates” Airbreathing Propulsion Award by the American Institute of Aeronautics and Astronautics as well as a departmental teaching fellowship. When asked about the research, Dumitrache said “The most important aspect of the research conducted at CLSD on laser ignition is that it brings together expertise from so many different fields such as: plasma physics, laser diagnostics, combustion chemistry and high-speed fluid dynamics.”

 

Recent ME Masters Graduate Receives National Recognition with Electric Propulsion Research

In the 52 years of electric propulsion research conducted at CSU, a student has never received the best paper award until now. Mechanical Engineering Masters Student, Carl Mullins, is the first. Mullins is one of many extraordinary ME graduate students who are generating national attention in their pursuit of advancing engineering on a global scale.

Carl Mullins (left) accepting Best Paper Award at the Joint Propulsion Conference in June 2015.

Mullins interest in Hall-effect thrusters (HET) led him to the development of a HET diagnostic system that can capture data from a HET while in orbit, or while being evaluated in a vacuum chamber on Earth.

A HET is a type of electric propulsion device that enables a spacecraft to travel farther and faster into space compared with a traditional chemical rocket; and they have been under considerable research since the 1960’s. What makes HETs unique is their ability to ionize propellant using electrons trapped in a magnetic field and then accelerate and expel the ions at high velocity to produce thrust. Currently, HETs are used to extend the function and life of Earth-orbiting satellites, and they are also slated to perform primary propulsion tasks on ambitious deep space missions.

Mullins’s innovation came to fruition using previous HET researcher’s work as a stepping stone, and with the assistance of CSU professors and students. The HET Diagnostic is a sensor that measures the magnetic fields generated by the HET during operation. Obtaining these data at high-sampling rates without disrupting the operation of the thruster can provide significant insight into the dynamic plasma interactions taking place, for example, Mullins’ imaging technique can quantify the previously unknown position of the current produced by the trapped electrons, and these data can subsequently be used to provide a real-time method for measuring thrust.

Mullins’ advisor and ME professor, Dr. John Williams, said, “All of our previous systems are focused on characterizing the properties of the plasma plume and the energy and charge state of ions in these plasmas. Carl’s research is our first forage into the area of obtaining high speed images of plasma current structures that can be used to study transient phenomena and to quantify an important parameter like thrust.”

CSU’s HET thruster

In the near future, Mullins hopes to put the HET Diagnostic to work in the field; collecting never-before-captured data and eventually developing it into a flight diagnostic for use in space.

“Although Carl’s work is amazing, all of our graduate students in the Department of Mechanical Engineering are working on similarly amazing and sometimes globally impactful projects, so please apply to our program or encourage a motivated person you may know to apply,” Dr. Williams added.

Mullins concurred, “The knowledge and experience I gained from CSU has launched my career and given me a valuable advantage over other graduating students in the field. The mentoring, hands-on experience, and innovative thought processes I was a part of at the CEPPE lab have molded the work I am able to do today. The education I received from CSU and John’s invaluable mentorship gave me the motivation to achieve my dreams.”

The sky really is the limit for this bright CSU graduate, and we look forward to sharing HET Diagnostic developments, as well as other groundbreaking discoveries made by our outstanding graduate students.

 

ME Alumnus, John Brophy, Revolutionizes Space Travel Using Ion Propulsion and is Honored with 2015 Robert J. Collier Trophy

John Brophy at the Cape in 2007

John Brophy at the Cape.

We are pleased to announce that the National Aeronautics Association named NASA’s Dawn Mission Team as the winner of the 2015 Robert J. Collier Trophy. Colorado State University mechanical engineering alumnus, John Brophy, is a member of that team and was responsible for the development of the ion propulsion system used on the nearly decade-long Dawn Mission, enabling it to visit the two heaviest main belt asteroids – the giant asteroid Vesta and the dwarf planet Ceres – a groundbreaking feat.

Launched in September 2007, Dawn is currently orbiting Ceres. The mission’s goal is to gather data from Vesta and Ceres, bodies believed to have formed early in our solar system’s history, to shed light on the characteristics of our early solar system and the processes that dominated its formation. Dawn is the first spacecraft in history to visit two extraterrestrial bodies, made possible by revolutionary ion propulsion breakthroughs developed by Brophy and his team. This honor is awarded to only the greatest achievers in aeronautics or astronautics in the U.S. with respect to improving the performance, efficiency, and safety of air or space vehicles. Previous winners have included Orville Wright in 1913, the
crew of Apollo 11 in 1969, Global Positioning System in 1992, and the Mars Science Laboratory in 2012, just to name a few – and now John Brophy and the rest of the Dawn Mission Team can add their names to this impressive list of pioneers.

What makes ion propulsion so groundbreaking? It allows us to reach farther and deeper destinations in space on spacecraft that use an unlimited source of energy from the sun.

Collier1

John Brophy with the Dawn Spacecraft

Traditionally, deep space missions are made on chemical rockets with limited energy available; however, this mission was carried out on an ion propulsion system using an external energy source, the sun.

For Dawn’s mission, Brophy’s lab, the Jet Propulsion Laboratory, developed a propulsion system that collects energy using large solar arrays and converts it into electricity, which is then run through the thrusters allowing for unlimited energy sent to the propellant. The propellant releases from the spacecraft at a speed 10 times higher than previous rocket engines resulting in a spacecraft that is 10 times more fuel-efficient.

Before this technology was recognized by NASA and used on the Deep Space 1 and Dawn missions, Brophy had many trials and tribulations with ion propulsion technology. Brophy became interested in ion propulsion in graduate school at CSU where he was a student of ME professor emeritus, Dr. Paul Wilbur. Upon graduation in 1980, Brophy got a job at the Marshall Space Flight Center and worked on a project called the Solar Electric Propulsion System, with the goal of building an ion propulsion spacecraft using mercury as the propellant. The project never came to fruition, in part, because of mercury’s environmental disadvantages.

The ion propulsion system used on Dawn runs on xenon as the propellant, an environmentally safe alternative. Ion propulsion systems have actually been around for a long time; however, it’s challenging to make an ion thruster last long enough to be useful, and it’s also difficult to master the blend of elements used to make ion propulsion successful.

John Brophy at CSU in 1978

John Brophy at CSU in 1978

After the ion propulsion system development at Marshall was canceled, Brophy once again collaborated with Dr. Wilbur at CSU for his Ph.D. to gain a better understanding of ion thrusters. After completing his Ph.D. in 1984, he joined JPL and eventually became the project element manager for Dawn’s ion propulsion system development.

In the early 1990s, Brophy convinced NASA’s New Millennium Program, which was designed to flight-test new technologies, that flight-testing an ion propulsion system was the most important thing it could do. Finally, in 1998, the New Millennium’s Deep Space 1 spacecraft was successfully tested on an ion propulsion system, and this set the groundwork for flying Dawn using ion propulsion.

The Deep Space 1 spacecraft spent about 16,000 hours in space, but Dawn shattered that record at about 50,000 hours in space – the longest- ever operation of a propulsion system in deep space. It became the highest-powered spacecraft that JPL had ever built for a deep space mission. Dawn’s ion propulsion system provided a far larger change in velocity to the spacecraft than any propulsion system in history.

Congratulations, John and the entire Dawn Mission Team!

Toward High-Fidelity Full-Engine Simulation

research_aerospaceimage1 research_aerospaceimage2Research in the CFD and Propulsion Laboratory is focused on the development and application of advanced CFD algorithms. Members of the group work with powerful research software in order to tackle the most vexing engineering challenges of our time. An example is to understand the physics of turbulent combustion and design improved combustion models for alternative fuels, which at some point must replace petroleum-derived fuels. High-fidelity models of the alternative fuel combustion process are necessary to reduce the expense of engineering simulations and thus allow a more thorough exploration how alternative fuels perform in existing and new propulsion systems. A long term goal of the group is to realize a full gas-turbine engine simulation on a petascale computer within the next 10 years. This can only be achieved by using highly-scalable and sophisticated CFD algorithms and advanced computer-science methodologies to extract maximum performance from next-generation computer architectures. Equally important is a close collaboration with scientists from multiple disciplines in academia, industry, and at Department of Energy national laboratories. Graduate researchers in the laboratory have the opportunity to work with a large collaborative team on designing some of the most powerful research software in the nation.

Dr. Xinfeng Gao
Email: Xinfeng.Gao@colostate.edu
Phone: 970-491-1003
Website: http://www.engr.colostate.edu/~gao/

Laser Sensor for Hall Thruster Erosion Measurement

Laser Sensor

Hall thrusters are widely used in space propulsion applications due to their high specific impulse, high thrust efficiency, and high thrust density. The thrusters experience sputter erosion of the insulator channel, which is the primary factor that limits thruster lifetime. An important area of Hall thruster research is to understand the erosion and assess thruster lifetime, for which advanced diagnostics of thruster is critical.

The Laser Plasma Diagnostics Laboratory, under the direction of Professor Yalin, is developing laser based cavity ring-down spectroscopy (CRDS) as a diagnostic approach to study thruster lifetime. The CRDS technique relies upon high finesse optical cavities to provide the high sensitivity needed to measure the sputter erosion.

Links:

Professor Yalin
http://www.engr.colostate.edu/me/pages/yalin.html

Laser Plasma Diagnostics Laboratory: http://www.engr.colostate.edu/lpdl