This document discusses plasma propulsion technology and research. It begins with definitions of plasma propulsion and related terminology. It then describes three main types of plasma propulsion: electrothermal, electrostatic, and electromagnetic. For each type, it provides examples and explanations of specific engines. It discusses current and potential future plasma propulsion research in Canada, focusing on small satellites. It concludes with some non-astronautical applications of plasma propulsion technology such as plasma gasification.

1. Plasma Propulsion
Technology in Astronautics
SYMPOSIUM ON PLASMA AND NUCLEAR SYSTEMS,
UOIT, Oshawa, December 22, 2016
by Dr. C. A. Barry Stoute, PhD
E-Mail: stoute.barry@gmail.com

2. Outline
1. What Is Plasma Propulsion
& Propulsion Terminologies?
2. Electrothermal Engines
3. Electrostatic Engines
4. Electromagnetic Engines
5. Fusion Propulsion Research
6. What Is Canada Doing in This Research?
Current Research
Possible Future Research

3. What Is Plasma Propulsion
& Propulsion Terminologies
• Plasma propulsion is a technology that the propellant is in an ionized,
or plasma state. The temperature of the plasma ranges from room
temperature to 5000 K and above.
• Plasma Propulsion can be achieved by one or more of the following
methods:
oElectrothermal
oElectrostatic
oElectromagnetic
• Each one is explained in detail.
• Propulsion Terminologies
oExhaust Velocity (𝑣𝑒𝑥) – The velocity of any particle as it exits the diffuser.
oSpecific Impulse (𝐼𝑠𝑝) – The measurement of fuel efficiency in rockets and
space engines.
𝐼𝑠𝑝 =
𝑣𝑒𝑥
𝑔0
=
𝐹
𝑚𝑔0

4. Electrothermal Propulsion
First, what is a thermal engine?
A thermal engine relies on the heat
transfer from a power plant or hot
element to increase the temperature of
the incoming cold gas for high thrust.
These are not combustion engines as:
• No oxidizers are involved
• No ignition for combustion
Electrothermal thrusters heat the
incoming cold gas from electrical power
sources, either DC or RF. Though in
comparison to other plasma thrusters,
this has the lowest specific impulse.
The principle theory of the heating
comes from Joule, or Ohmic, Heating
showin as:
𝑃𝑎𝑏𝑠 =
𝑉
𝜔 ∙
1
𝜔
𝐉 ∙ 𝐄𝑑𝑡 𝑑𝑉
NASA’s Nuclear Engine for Rocket
Vehicle Application (NERVA)
The exhaust velocity is determined
by the pressure differential. The
higher the temperature, the higher the
exhaust velocity. This increases the
specific impulse. The full equation of
the exhaust velocity is:
𝑣𝑒𝑥 = 𝑇𝑖 ∙
R
M
∙
2𝛾
𝛾 + 1
∙ 1 −
𝑝 𝑒
𝑝𝑖
𝛾−1
𝛾

5. Electrothermal Propulsion
Types of Electrothermal thrusters
Resistojet Thruster
Arcjet Thruster
RF Thruster
Resistojets utilize resistors as heating
elements for ionization. The process is
inefficient because the cold gas passing
through the resistor, it cools down.
Arcjets are thrusters that the plasma is
ionized by a high voltage DC source. The
current is minimal; however, the heating is
solely dependent on the potential difference.
RF Thrusters are sought to be the best
option for electrothermal propulsion.
The power required to heat the gas is
significantly lower than an arcjet and the
configuration can be electrodeless.
The problem with RFTs are designing and
building the RF system as it is difficult and
expensive to build.

6. Electrostatic Propulsion
Ion and Hall Thrusters
The principles of electrostatics is
the basis of electrostatic propulsion:
electric and fields accelerates the ions
at hypersonic velocities in small
quantities. These engines have one of
the highest specific impulse among the
plasma thrusters.
There are two primary types of
electrostatic thrusters: Ion and Hall.
These will be discussed in detail in the
next slide.
Ion and Hall thrusters are
commercially available and have been
implemented in the aerospace industry.
These thrusters are design for deep
space missions, such as NASA’s
NSTAR and Snecma’s PPT-1350
NASA’s NSTAR Ion Thruster: This was the
propulsion system for the Deep Space 1 satellite to do
a flyby of asteroid 9969 Braille
Snecma’s PPT-1350 Hall Thruster: This was the
propulsion system for the SMART-1 satellite to do
scientific observation of the moon

7. Electrostatic Propulsion
Types of Electrostatic thrusters
Ion Thruster
Hall Thruster
All ion thrusters have these key elements: generation
chamber, two electrodes and a neutralizer. The two
electrodes, screen and acceleration, create a high
potential difference between them. The ions drift into
the orifices of the electrodes and are then accelerated.
The ions are neutralized once out of the thruster to
prevent charging. The exhaust velocity of the ion
thruster is measured as 𝑣𝑒𝑥 =
2𝑒𝑉 𝑏
𝑚 𝑖
Hall thrusters operate in a different manner than ion
thrusters. They are operating by using the neutralizer
as an ionizer. The electrons are trapped in a magnetic
field, freely rotating around. The incoming gas
bombards the electrons, causing ionization. The
concluding exhaust velocity is determined by the drift
velocity of the electron and the magnetic field
𝒗 𝒆 =
𝐄×𝐁
𝐵2 , 𝐉 𝜃 = 𝑒𝑛 𝑒 𝒗 𝒆, 𝑣𝑒𝑥 =
𝐹
𝑚
=
1
𝑚 𝑉
𝐉θ × 𝐁 𝐫 𝑑𝑉

8. Electromagnetic Propulsion
Introduction
Electromagnetic propulsion is sought to be
the most powerful plasma thruster before
fusion rockets. The principle operation for
these rockets is the plasma acceleration by
the Lorentz Force:
𝐅 =
𝑉
𝐉 × 𝐁 𝑑𝑉.
Electromagnetic thrusters tend to have
problems creating the high current required
because the limitation of onboard power
supplies. There are two solutions to the
problem. The first solution is to use external
magnetic fields to accelerate the plasma. The
second solution to this problem is to run
these thrusters in quasi-steady state. Quasi-
steady state uses pulsation from the power
supply and the charge capacitors.
Current energy systems research searches
for high energy density power sources for
deep space missions where solar power is not
available. With this research, the need for the
quasi-steady state would diminish.
Ad Astra’s VX-200 VASIMR (Variable
Specific Impulse Magnetorocket) in
operation.

9. Electromagnetic Propulsion
Types of Electromagnetic thrusters
Pulse Plasma Thruster
VASIMR
Pulse Plasma Thrusters, or PPTs, uses solid
fuel, namely Teflon, as a propellant. A spark
plug ablates and ionizes layers of the fuel, and a
high current accelerates the plasma.
Magnetoplasmadynamic, or MPD, thrusters are
the purest form of electromagnetic propulsion.
Incoming gas enters the thruster, and high
voltage and current occur between the nozzle
and the tip. The gas is ionized and accelerated.
The variable specific impulse magnetorocket
(VASIMR) is a hybrid of electromagnetic and
electrothermal propulsion. The gas is heated and
ionized by high power RF supply. The plasma is
controlled by magnetic fields to prevent the
particles touching the walls (similar to MCP),
and the plasma is accelerated by an external
magnetic field.
MPD Thruster

10. Fusion Propulsion Research
Fusion propulsion is currently being
researched at many institutions around
the world: United States and Europe.
The use of fusion propulsion will
revolutionize space travel. The time it
would take to travel to Mars, for
example, reduces significantly.
University of Washington’s
Electromagnetically Driven Fusion Propulsion
University of Alabama Huntsville’s
Z-Pinch Fusion Propulsion
Los Alamos National Laboratory’s
Magnetized Target Fusion Propulsion

11. What Is Canada Doing in This Research?
Current Research
Currently, there is research on
miniaturization of electrostatic and
electromagnetic propulsion systems for
nanosatellites. Undergraduate students
from University of Waterloo and York
University have developed electric
thrusters for their senior year project.
PhD graduate Barry Stoute from York
University has developed a hybrid
electric thruster design for nanosatellites.
A paper has been published on the
design of low-cost ion thruster at
Canadian Aeronautics and Space
Journal in September 2015.
Otherwise, the basis of plasma
propulsion is used on material and
fusion engineering. Universities such as
McMaster University work on plasma
etching for MEMS development.
University of Saskatchewan, UOIT, and
CNL are currently doing research in
fusion power.
Hybrid Electric Thruster: Parallel combination of
electrostatic and electromagnetic propulsion systems
for nanosatellites developed from York University
STOR-M Tokamak currently located at the University
of Saskatchewan

12. What Is Canada Doing in This Research?
Current Research – Electrothermal Thruster Test In
Action

13. What Is Canada Doing in This Research?
Possible Future Research
Canada can be the leader of plasma
propulsion by concentrating on small
satellites.
The industry of miniature, micro, nano,
and picosatellites are growing
exponentially due to their low cost and
light weight. Canada can lead the charge
by developing miniature ion thrusters.
What is required to lead the charge?
• Plasma Physicists to research the
behaviors of charged particles
benefiting for propulsion
• Engineering Physicists to create
miniature thrusters by using MEMS
• Chemical and Material Engineers to
develop new fuels for the thrusters
• Mechanical and Electrical Engineers
for development of the thruster
George Washington University’s miniature
plasma thrusters
Nanosatellites at University of Toronto

14. Some of Non-Astronautical Applications
of Plasma Propulsion Technology
There are some non-astronautical
applications that are derived from
plasma propulsion technology.
Plasma gasification is one of many
applications in which arcjet or RF
thrusters are used to incinerate waste.
The waste is converted to a synthetic gas
where it is used in the Rankine Cycle.
Another application is to use
electrostatic thrusters as ion sources for
surface engineering and thin films.
Hollow cathodes and Hall Effect ion
sources are used in this particular
industry.
In fusion energy, ion thruster technology
is used for neutral beam injection for
the tokamak at ITER. This is an efficient
source of plasma heating for fusion.
Thermal Plasma for Gasification from
Westinghouse
Neutral Beam Injector from the Tokamak at ITER
Image from Max-Planck-Gesellschaft

15. Thank you for your
attention
Questions?
Dr. C. A. Barry Stoute, PhD
E-Mail: stoute.barry@gmail.com