After a grueling interview process at the end of the first year of my Physics undergraduate studies at Imperial College, I was given the unique opportunity to become a young researcher for eight weeks over the summer in the Plasma Physics Department at Imperial College.
My work involved helping to build something that can accelerate charged particles, like electrons that make up me and you. It was called a Wakefield accelerator and it could fit on your coffee table!
Here is what the vacuum chamber for the wakefield accelerator looked like:
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| Vacuum chamber that I built with Dr. Christos Kamperidis of the Plasma Physics Department at Imperial College |
But like you, I had no idea what this object was, what it could do or what it was useful for - as far as I was concerned it was just a metal cube! I shall try and explain how a Wakefield accelerator works in simple terms later in this blog.
But first let me tell you about my experience in the research group - day 1.
When I was introduced to the staff in the Plasma Group I wasn't surprised to find that there was only one female in the Group. So I felt quite alone and a bit uncomfortable having all these male brains in the room. I certainly felt the initial judgement that I wasn't clever enough for the Group or so I felt... I was introduced to the project I was going to be working on and immediately I was overwhelmed by the information! I didn't even know what a plasma was let alone what plasma acceleration was! But after a day or two of solid research I quickly grasped the information and I was able to understand what on earth the Plasma Physics Group were on about! I surprised my supervisor with my knowledge and that made me feel on top of the world because I broke the stereotype of females being too 'dumb' for Physics. Day 5 and I was ready to show all those male brains in the Group meeting that I could do as well as the boys. Luckily all my hard work that week paid off and they didn't think I was stupid, I felt a part of the team and that my input was valued.
By the third week I was getting into the nitty gritty parts of my project and I started to build the vacuum chamber that would house the plasma. Before I continue, as I mentioned earlier I shall try and explain what Wakefield acceleration is using simple terms.
Wakefield acceleration is a form of acceleration of charged particles using a plasma. Plasma is the fourth state of matter. Think about some ice (a solid) you
have in the freezer, if you take it out the warmth of your surrounding makes
the ice melt into water (a liquid) then if you put the water in the kettle for
your cup of tea some of it evaporates into steam (a gas), and if we were to
heat this steam then we would get a plasma.
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| Illustrates the four states of matter |
A plasma is a substance that
has been heated to the point where atoms can’t hold themselves together and so
exist as a soup of electrons and ions. To see how it works, let’s consider a bunch of electrons are injected
into a plasma, which as aforementioned is a soup of ions and electrons.
Due to the injection of the electron bunch, electrons
in its path will be repelled and positive ions will be attracted. As the
electron bunch passes through the plasma it leaves a wake much like the waves that
a boat leaves as it travels through water. A channel of positive ions is formed
and the electrons are repelled and move towards the back of the electron beam
towards the positive ions also repelling the electron bunch causing the
electron bunch to accelerate. This process continues until it reaches a maximum
speed.
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| Illustrates plasma (Wakefield) acceleration |
As
an analogy plasma acceleration is a lot like surfing. Imagine a boat with its
bow (front part of boat) tilted upwards speeding through the water and a huge
wake ripples behind it. A surfer could take a free ride on these ripples just
like the electron bunch mentioned earlier ‘surfing’ its own wake and gaining
energy. The boat that initiates the wake can either be an electron or proton
bunch or a laser beam. The lake can be considered to be the plasma.
My project involved using a laser as the boat to drive the acceleration and create the wake. But for efficient acceleration this needs to be done in a vacuum chamber. So the vacuum chamber pictured above was built and connected to a vacuum pump - it reached a vacuum that was even better than the vacuum of outer space!
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| The vacuum of the chamber measured in the units, millibar. |
Part of my project was to also design the shape of a gas nozzle for the nitrogen gas that would enter the vacuum chamber . The nitrogen gas shall form the plasma we need when the high energy laser pulse causes the nitrogen to lose electrons, a process known as ionisation.
The design for the gas nozzle was done using a computer program called OpenFOAM. I only had eight weeks to familiarise myself with the program and since I had little computing experience this was quite a tedious process but I managed to get this far:
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| Shows the flow of nitrogen gas (bottom) into a vacuum chamber (box above). |
This was a huge achievement for me since I didn't even know what computing was nine months before the placement. I introduced the head of the Group to the Raspberry Pi, a mini computer and managed to hook up three webcams to it and create live streams using the local network which would later be used to monitor different parts of a laser system from another computer connected to the local network which could be ten floors up!
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| The Raspberry Pi, a mini computer |
I would definitely recommend a Raspberry Pi to anyone, no matter your age - it can be great fun and you'll learn about the wonderful things you can do with code too!
In addition to this, I got to design a gas nozzle using CAD software, where CAD stands for Computer Aided Design - so I used a software called AutoCAD where I used shapes within the software to make the desired nozzle shape and here it is:
When converted into the correct file format this could be sent to a 3D printer and then 3D printed into reality!
As an added bonus, I was very privileged to be able to see the laser facility being built at Imperial College - right beneath the lecture I sit in! I shadowed Dr. Christos Kamperidis and Katalin Mecseki, two wonderful postdocs that were kind enough to let me see them working with a rather cool laser system!
As the cherry on top I was able to visit the huge laser system, Gemini, at the Rutherford Appleton Laboratory's Central Laser Facility in Didcot, Oxfordshire. The laser facility was huge and by far the largest piece of equipment I have ever seen!
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| You can just about make out the clean suit I had to put on when I was viewing the laser system, Gemini. |
I also took a chance to have a look around Rutherford Appleton Laboratory (RAL) - for any teachers out there reading this you can take your students to RAL, check this out:
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| The atom tree |
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| The atom tree at RAL |
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| An unused control room - the room next door to the active control room I visited |
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| Posters decorate the area, recently put up. |
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| The above reminded me of a school trip with my inspirational Physics teacher when I was in year 12 back in 2012! This moment changed my life, this trip showed me the applications of Physics in Medicine and completely changed my view on the subject - I could change lives with Physics! |
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| School trip back in 2012! |
I certainly didn't think I would contribute so much to the Group - it was an experience that shall stay with me forever. I was able to fit into a male-dominated Group and contribute too! So for all you, young scientists out there, especially the girls, don't ever think you are not good enough because I am sure you will be pleasantly surprised when you step outside your comfort zone and try something new! I've mentioned this saying in a previous post but I think it deserves a mention here:
'You are all stars you just have to initiate that fusion!'.
Although physics might seem like a male subject, we girls can do as well as the boys (if not better!) if we put our mind to it. There are so many females out there discovering great things and you can do it too! Why not email a real scientist and find out about the work they are doing, take part in a science workshop, go to a public science lecture or take part in science projects; whatever it may be get involved with science and maybe you'll catch the science bug!
“When I started secondary school, we had the opportunity to undertake more experiments such as chemical reactions and energy. First came energy, where we had to understand different types of energy. This was a fun experience as I learnt about the different types of energy. Next were chemical reactions, which is my favourite part in science. We did experiments such as testing for oxygen, carbon dioxide and hydrogen. We also did mixtures of acids and the PH scale. This was an exciting thing to discover as I always wanted to play with acids and see what different things I can do with them. As you can probably figure out my favourite topic is chemistry.”
