This video is sponsored by Nebula.
Okay. Rolling.
Whoa.
Lots of people follow this YouTube channel
because of the vlogs I made during my Ph.D.
in atmospheric physics at the University of Exeter.
Unfortunately, however, I had to graduate at some point, and that necessarily meant
the end of my videos showing what doing a PhD was like.
However, there are lots of people out there doing interesting PhD projects.
And so in this video series, I'm spending a few days with a new researcher
each episode showing you what that life is like,
learning a bit about them and learning about the topic of that thesis.
This time I'm up to the Department of Aeronautics at Imperial College London
talking to Jesús, who is experimenting with an unusual rocket fuel...
water.
I'm Jesús, I’m a PhD student at Imperial College London
and I am in my third year of my PhD research.
So my PhD's title; computational and experimental
characterization of water fuelled Hall Effect Thrusters.
In simple terms, what we are trying to do is to develop a spacecraft
propulsion systems that instead of using normal propellants
like the ones that are being flown into space, right now they're using water.
In space propulsion systems, there are two main categories.
You have chemical thrusters, which are the rockets you see every day,
like NASA and Space X with all this like massive burn out of propellant.
And then you have electric propulsion systems,
which is the ones I'm developing myself.
In chemical rockets, you have a chemical combustion
and this is how you create propellant.
In electrical systems, what you do is that you create a plasma.
And then by sort of using an electrical magnetic field,
then you accelerate the plasma, you get force from it.
The good part about these systems, which are like conducted by plasma,
is that they are very, very efficient because chemical reaction, let's say
inefficiencies because you can generate a lot of heat, also like energy
being uncontrollably released from the components of the propellant.
Whereas if you have an electric propulsion system, what you have is something
that is like very, very fine tuned and you can generate the plasma
and you utilize most of it to actually generate thrust.
But the disadvantage is that the thrust you produce from the systems is
very, very, very small.
You have a coin in your hand and the weight of the coin
is more or less the thrust that these systems are producing.
In space,
what happens is that as you don't have any kind of friction or whatsoever,
you are like floating.
Even if you have a small coin pushing and you keep on pushing
for like years, you build up a massive acceleration.
And this is because something pushing for a very, very long time
starts to accelerate the stuff more and more and more.
And as there is nothing to stop it, at the end, you get a very, very high speed.
This kind of technology is already used on spacecrafts.
For example, the recent DART mission used an ion thruster.
The most commonly used fuel in these is the gas xenon because it's
massive, inert, not radioactive, and has a high ionization potential,
meaning it's easy to rip an electron off and generate a plasma,
but other noble gases like Krypton are used to.
Unfortunately, however, producing these gases is very energy
intense and expensive.
So this is investigating alternative fuels that are a bit easier to come by.
For example, the propellants that we use nowadays are very toxic
and enviromentally not friendly, and also they are very, very pricey.
So we want to come up with a solution that solves all these problems.
While it can also be found in the vicinity of the entire solar system.
When I arrived,
Jesús was actually repairing a component of the experiment
that had developed a fault over the weekend,
something that had to be fixed before we could film.
That meant that he asked me to climb into the vacuum chamber
to recalibrate a part of the experiment.
Now, this may surprise some of you, but I don't actually own a lab coat.
It's not like a requirement to being a scientist, that you own a lab coat.
But I have been given for the shoot today and I'm allowed to keep this
My very own lab coat.
So what I want you to do
here, you're going to see that a laser and this laser
is in charge of measuring the displacement of this thrust components.
Woah.
Yeah, it’s super slippery
I feel like I’m in like a kid's playground,
a very, very expensive playground.
So this whole slab moves slightly.
So when the thruster is firing, you're going to see this be pushed backwards
and you're going to measure that using this laser that's down here.
So you bring it closer.
It will start to turn green.
And that means that the distance between the blade and the laser is right.
So is green too close?
The green is fine.
Red is too far away.
And orange is like, sweet.
So now it's green and it's going to turn orange just for...
Oh, there you are.
Yep. perfect.
Nice.
Well, I honestly never thought doing this job, i’d be recalibrating a component.
In a plasma thruster experiment.
Here is a Hall Effect thruster, let's say, in very simple terms.
It's a device that has an inlet in which the propellant is being injected.
And then it has a very specific magnetic field topology.
So in this region that you see here is where the plasma is being generated
and it's being confined by all this equipment that you see
and then it’s being expelled out of it.
How do you actually generate the plasma?
The Hall Effect Thruster as itself.
It means nothing is useless.
We need to have something called a cathode,
which is an electron gun or a neutralizer.
This system is the one that is emitting electrons, and the emission
of electrons from this cathode is the one that is going to excite the plasma.
And this collision between the electron and the neutron
if it is very energetic, can generate an ion
And then there is a snowball effect in which in case you have one ion,
then you start generating two ion three ions
and at the end you have plasma being expelled.
The good part about our kind of equipment is that you only need to do this
and then you have fuel for your spacecraft.
What you can do is you can have any kind of system
that changes from liquid water to water vapor,
and then water vapor is being ionize.
And this is how you propel your spacecraft with water vapor.
The other alternative, instead of using water vapor,
you can have a water electrolyzer in front of your spacecraft.
Water electrolysis propulsion is very, very useful because you separate
two propellants that serves two need at the same thing oxygen for the thruster,
hydrogen for the cathode.
There are several kinds of ion thrusters.
And as he already mentioned, the thruster you just saw in the vacuum chamber,
the subject of Jesús’ PhD
is a specific
kind that uses something called the Hall effect.
The Hall effect
is the movement of charged particles when they're in a perpendicular
magnetic field.
It's a very cool phenomena because you have two things.
You have the electric field and the electrons trying to go through one area
and then you have the magnetic field and the electrons are trying to gyrate
So you mix on a straight line and a circle.
What you have is a kind of ellipse.
So it's like doing this kind of motion in which on one hand
it wants to get out,
but on the other hand is being forced to do this circular motion.
And all this stuff is built up in this radius of the Hall Effect Thruster
so that we increase the amount of time
that the electrons are inside of the channel.
Because if the electrons are there for a long time
is going to be statistically more probable that you are going to hit an electron
with a neutron and it's going to generate an ion.
So by increasing the amount of time the electrons are within the channel,
increasing the amount of probably probabilities
of having an electron, an ion, and then therefore the plasma.
Over the course of the day we filmed, we fixed the component and sealed
the vacuum chamber and started pumping it down to very low pressure.
After all, this is equipment designed to operate in space.
It would be impossible to get the plasma engine to work at atmospheric pressure
that pumping down gave me a chance
to ask Jesús about his background and the unusual way his Ph.D.
was financed.
I studied in Spain, in Madrid for my aerospace engineering background,
and then I moved
to the Netherlands to TU Delft, and I studied there my master's degree.
And then I moved to Switzerland at CERN, the particle accelerator.
Two years there of work experience.
And when I was working there I was also working at the Swiss Space Center,
which is like the entity in Switzerland that manages all this space stuff.
What happened was that I was in Switzerland with a very generous payslip.
I said, I went to the a PhD like 100%, right!
So a talk with my supervisor.
I didn't have any funding and he accepted me as a PhD student
being self-funded.
At the start, I didn't have any funding, as I said.
So I was like here on my own.
And I took this chance because I love science
and I wanted to do something
that really like fills my heart and then after one and a half years
of like working here, being self-funded, I got funding for my PhD.
So the European Space Agency found my project interesting
and now I'm getting paid by them to conduct these experimentation.
Do you play Kerbal Space Program?
Oh yeah, that's a very good game.
Played a little bit and is quite realistic.
Like the stuff you can generate there apart from like dark matter
and the other kind of energy that are not yet there yet.
I think it's a very realistic firmware.
Now when Jesús emailed me about his project, he mentioned that
we could generate some plasma and get the engine working for the camera.
Great.
But there was another facility at Imperial
that he mentioned that got me really excited to visit.
So why do you have a flight simulator?
First of all, for the students of the first and second year to actually
like experience what actually the physics of motion of an aircraft
and also the PhD students and professors that give like do research on it.
The good part
is that you can model your own aircraft and you can see how you actually would
perform in reality.
So as a student, you can design an aircraft,
you can put that into the system, and then you can control that aircraft
and see how it handles in a six axis flight simulator.
Yeah, precisely!
Another big project in first year.
It's called “Aerial Vehicle Design” and there's also one lab in second year.
I think you have to design a control system.
An autopilot!
haha this is so cool!
Does this have anything to do with plasma thrusters?
No.
But how many times do you get an opportunity to fly one of these?
We’re about to fly what I think is a fighter jet.
This can only go well.
Locking the doors.
Okay, that's on.
All right, whenever you're ready.
Simon, press the start button
Ready?
Full throttle.
All right.
Yeah
Woah
Current speed
Current speed mach one
Woaahh
So which direction we are heading?
West, is that correct?
Let me double check, you are heading east.
right, okay, down we go.
We are Buzzing Central London at 400 feet.
Gwoooaooooh, God,
bit of turbulence, good grief!
*muffled screams*
600, 700 feet
I recommend decreasing the speed
Good grief, okay.
You're going to be in charge of the parking brake.
That's a tree!
That's a building.
We are bouncing around southeastern England.
I think we may have crashed
I feel a little bit motion sick, I won’t lie.
Oh, I do. Yeah, actually. Oh, my God.
Thank you Jesús
Yeah, that was amazing.
Someone's glad they're on solid ground.
So what we're going to do now,
we're going to try to ignite the thruster using oxygen, and oxygen when we turn
the plasma on is going to be a mix between green and yellow.
And this is because every plasma brights, has a certain
wavelength that our eyes interpret as a different color.
We are going to generate electric field between the thruster on the cathode
That's the first step.
And the second one is that we're going to put propellant through the thruster.
So the combination of the electric field plus the propellant
is going to create this plasma that we're going to see.
And the third step is to start the magnetic field.
And when we start the magnetic field, we're going to have a Hall Effect Thruster
electric field, magnetic field and a plasma in between it.
And then what kind of force are you expecting to generate.
Today?
probably...
30 millineutons
something like that.
I think the building will be all right.
Okay.
Whenever you are ready.
Ready!
Alright, let’s give it a try
Over the course of the afternoon, we fired up the plasma thruster
dozens of times, testing, putting different quantities of oxygen
through the thruster, depending on the concentration
of oxygen plasma, it would appear anything from green to yellow.
A bit like how the note of a car engine changes depending on the fuel
mix you use and generate slightly different amounts of thrust.
But needless to say, it all looked awesome.
So in the future what we want to do is to put this stuff out into space.
Right now
we are making sure that the efficiency levels on the technology is competitive
and once we have all this research done,
what we want to do is to fly it in an actual spacecraft in orbit
with the proof of concept and then commercialize it.
If I will have to choose a space mission for this,
probably I will choose to go to one of the moons of Jupiter.
If you go there, you need something that is very, very efficient.
So you can not use like a standard rocketry.
And if you use Hall Effect Thrusters, you can use this
propellant for interplanetary missions or for example, going to Jupiter
and explore one of the moons of Jupiter possibly
gather water from this planet in order, for example, to come back to Earth.
My idea after my PhD is currently unknown, I would like to like keep working
in the space field if possible like work for any space agency.
I think that would be great.
Otherwise I might spread the word of science
as you do and join your your stuff, which is also very good.
Do you think you'll see this technology being used in the next couple of decades?
Yeah, for sure.
Like I think the time scale is probably...
being optimistic
ten years
Being pessimistic, maybe takes twenty
It maybe a decade or two from being used on a mission.
But what you've seen today may not be the last time
you see a water fueled spacecraft thruster.
The next time might just be around one of Jupiter's moons
Putting these videos together is tough because every one of the PhD students
I featured in this series have had such interesting
stories to tell, and you can only cover so much in a video.
For example, this isn't Jesús' only research project.
Previously, he worked on transformable spacecraft
and was even invited to fly a prototype of one on a microgravity flight
by the European Space Agency.
He talks about this as well as giving advice to prospective PhD students
in an extra video I've uploaded to my Nebula page,
most episodes of the series actually have such bonus content on Nebula,
which is the streaming service.
I am lucky enough to run with a team of creator friends.
Over a 600,000 people have signed up to Nebula and it's not hard to see why.
There are over 100 educational creators uploading their videos to Nebula,
so it's got tons of exclusive content, like my extended videos, but also Nebula
Originals such as Abi Thorne's, The Prince, Extremities, and Great Cities.
So it's like the section of YouTube you already watch, but with bonus content
and with no adverts whatsoever.
Nebula instead operates on a subscription model
with your subscription fee divided between the creators you watch.
So by signing up and watching videos from me,
you directly support this series and further videos from me.
If you sign up with my link in the description, you get an amazing
40% discount on a yearly subscription, meaning you can support my videos,
stop seeing adverts on videos from your favorite creators
and be introduced to new series and new faces for just 2.50 a month.
And for that 2.50 a month, you also get free access to nebula classes
where nebula creators show you behind the curtain
and how they make videos and in-depth lessons.
It may well be the best money you spend this year,
and while I would certainly appreciate it if you went to go.nebula.tv/SimonClark
I think you are going to appreciate it, too.
Thank you for watching the video.
And thank you, of course, to Jesús
for being so generous with his time and letting me on that flight simulator.
If you enjoyed the video, please do pop it a like
and share it with your friends who you think may be interested.
But also do check out previous episodes of this series linked on the screen
and in the description that just leads me to say thank you again for watching
and I'll see you in the next one.