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2006 SPS National Interns
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Jeff Lee
Jeff Lee
St. Mary's College of Maryland, MD

Internship: NASA Goddard Space Flight Center
Online Journal
Week of August 4, 2006 Week of July 14, 2006 Week of June 23, 2006
Week of July 28, 2006 Week of July 7, 2006 Week of June 16, 2006
Week of July 21, 2006 Week of June 30, 2006 Week of June 9, 2006
Week of August 4, 2006

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Week of July 28, 2006
This has been a very good week. I tested the detector for the LENA lens system, and everything went fine. Then I attached it to the lens, and we are just about ready to test conversion surfaces. The final plans for the wiggler's mounting bracket are also done so that should be made soon. All in all, the LENA project is moving along quite nicely.

There was also a lot of progress with GEMS. I realized that we did not in fact need to get a deflector made, because there is already one in the chamber that we have never used, so we kind of forgot about it. The location of this deflector does change the details of the experiment, but the basic idea is the same. After we realized this, it only took a little while before we were ready to try it out for the first time. The first spectrum we took was just about perfect. After the first trial though, we started noticing an interesting feature in the spectra. I think I know what it is now, but it was quite a mystery for most of the week. Involvement with GEMS so far has just been proof of concept, since what we are doing is a new way to do TOF spectroscopy. This has been a success, and now it just needs a lot of fine tuning and tweaking.

This week is the last week of the SPS internship program, but Fred found another contractor to hire me for the rest of the summer to continue with the LENA and GEMS projects. Also, because of how close my school is to Goddard, Fred and I have been talking about the possibility of doing my senior project in conjunction with NASA. If this does happen, I would be working solely on GEMS, attempting to create a compact neutral gas analyzer. This is all very exciting, and I am glad that I had the opportunity to do the work I am doing.

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Week of July 21, 2006
This week was interesting because the two people I work with were gone all week, but I was left with a good sized list of things to do in their absence. First of all I spent a lot of time trying to get the GEMS project working. I never thought that it would be so hard to make the circuits we needed, but with the help of and electrical engineer who works with Fred, we got it done. Next week we will make a small deflector to go into the chamber, and then we should be ready to get a mass spectrum.

Other than working on the electronics for GEMS, I was also given the task of testing the detector for the lens system. We eventually got it to be stable with the high voltage on it, and next week I will be putting in a feed through so that we can actually use it to detect ions. Also, instead of getting a part machined to attach the detector to the lens, I improvised a little bracket, so after we test the detector, it is ready to go.

Next week should be quite busy. I have to get the deflector for the GEMS made, and I also need to use this same deflector working for the LENA project. Then we need to test the lens system. Finally, I need to get a bracket machined to attach the wiggler. Once this is done, we can test the wiggler which will probably take up the rest of the week.

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Week of July 14, 2006
The wiggler is finally done. I got it back from the platers on Monday and assembled it. Now all we need is a simple mounting bracket, and it should be ready to go. Since we now have to wait for this bracket, I spent most of my time this week trying to get a lens system and detector working. This lens system tests the conversion efficiencies of the conversion surfaces that Bill is making at College Park.

First we had to do a high voltage test of the lens to make sure it doesn't blow up when we try to use it. We want to be able to get it up to about 10,000 Volts, but when we get to around 5,000, there are fluctuations in the current through the lens. This is when we realized that the resistors we put on it were not rated to handle as much power as we were putting into it, especially while in vacuum. Other than that, it was working fine, and until we get new resistors for it, we can just run it at a lower voltage. The detector for this lens system also had to be assembled. The design for the lens came from College park, so I took a trip over there this week to see how they mounted their detector and lens, so I can do the same for ours. In order to do this, we will need to get couple more small parts machined.

We also started setting up to run the GEMS project. It uses the microchannel plate, and special PCI card to organize counts form the MCP in time bins as small as a nanosecond. This week, I made room for the computer with this card on it, and set it up in the lab. Then I eventually got it to count pulses coming from the MCP. Now we need to make a couple of simple circuits to control an electrostatic deflector so we can see if it works. That, along with setting up the lens system in the chamber, will be my task for next week.

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Week of July 7, 2006
Well the wiggler was supposed to be done this week, but something got messed up with the money for it, so hopefully that will all get worked out, and we will have it next week. In the meantime, we ordered the special kinds of screws and washers that we need to assemble it. Other than that, I had a pretty fun week. On Monday and Wednesday I spent a lot of time assembling the feedthrough that we need in order to supply the wiggler with the voltages it needs. Also, I designed and ordered a custom flange for the chamber so that we can actually put this feedthrough in.

Thursday was a very frustrating day. I had left the ion beam running overnight in the hope that it would get a little more stable, but when I got there in the morning, there was nothing. After trying to figure out something else that it could be for a while, we finally decided the problem was that the filament had burned out in the ion source. The reason we tried to find something else for the problem to be was that the filament is just about the hardest, most time consuming thing in the chamber to get at, so you want to be very sure if you are going to take it out. After we decided to change the filament, I spent quite a good while trying to find the replacement filament, because the only person who knew where they were was in a meeting. After we found the replacement, we spent the rest of the day changing it. I suppose it was a good experience though, because I got to see inside of the ion source, and better understand how it works now. There was a bright side to the day though. After work, I met a few of my friends from school, and we had dinner in the city.

We didn't get a chance to test the ion beam on Thursday because changing the filament took all day, so that was the main task for today. When I finally got it up and running, there was another problem. The intensity of the beam had dropped by about a factor of 100. After a lot of thought, we still don't know what the problem is, but as it turns out we don't need to. The microchannel plate that we have cannot be used with a beam as intense as what we had, so we would have had to drop the intensity to about what it is now. Since our current beam is stable, although weak, it will work fine. Now we can run our experiments using the microchannel plate as our detector instead of what we had been using. This is very good because the microchannel plate is much more precise, and responds much faster.

Next week, hopefully, we will have the wiggler ready to go. Also, I am going to start working on another project with Fred called GEMS (gated electrostatic mass spectrometer). This project has to use the microchannel plate, so now that it is working we can start next week.

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Week of June 30, 2006

This week was a lot of fun. One of the most enjoyable things I did this week was making the new controller for the Wien filter. The circuit was about as simple as a circuit can get. It consisted of nothing but resistors, however instead of just soldering them on to a perforated board, we decided that it would be better (and more fun) to try and make our own printed circuit board. I have wanted to do this for a while, but have never had the chance. Basically, you start with a copper plated fiberglass board, cover the copper you want to keep with a marker, and chemically etch away the rest. This leaves you with little wires of copper on the fiberglass board. Doing this was a lot of fun, but testing it was interesting. The design we came up with uses huge resistances to limit the current, and when we tried to measure voltages, the voltmeter's resistance was too small in comparison, so the voltmeter actually changed the voltages instead of measuring them. We eventually found a better voltmeter with a much higher resistance, and tested the design.

Also, for the past few days, I have been working with the machinist, Jay, who was building the wiggler. Since this was my first time making fabrication drawings, they were not quite as detailed as they are supposed to be. Jay was quite understanding though, and nicely let me know everything that I did wrong, so next time should go a little better. Finally, though, it is done. Today, I tested to make sure that everything fit together properly, and after a few minor alterations, we gave it to the platers, and they should be done with it by Monday afternoon. Now all we need are some special washers and screws, and it will be done.

Today, also, we tested the microchannel plate. While we were setting it up, I got a nice lesson about how exactly it works, along with all of the electronics associated with it, and by the time it we turned it on, I knew enough to realize that it did in fact work. Next week, we should be assembling the wiggler, and designing the mount for it inside of the chamber, and probably testing the microchannel plate a little more thoroughly.

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Week of June 23, 2006
Most of my work this week was actually coming up with drawing of the wiggler that I designed so that we can make a real one instead of just a simulation. That was interesting, as I have never done this before. My biggest mistake was giving all of the dimensions in metric when apparently all machinists use English. Other than that, I don t think I did too poorly, and we were told that it should be done by around the end of next week, which is quicker than I thought it would be. Also, we worked on getting better spectra from the ion beam with a little luck, and we think we know what to do to make it better.

The most exciting part of my week was the day we dropped off the drawings to the machinist. First of all the machine room was very interesting. I have never seen machining tools anywhere close to this size before. After we left the machine shop, Fred took me, along with a couple of other students, around to a few buildings of interest on the Goddard campus. First we saw the room with all of the gigantic vacuum chambers they use to test all of the gigantic equipment they put into space. The biggest one was about 250 feet wide and 400 feet tall with 16 individual vacuum pumps on it. In the same building is the big centrifuge they use to test how astronauts deal with high accelerations. Apparently this is the same one they have had since they first started in 1960. The most recent tests they have done with it have been roll over tests on SUVs. Finally we went to the building that has the largest laminar flow cleanroom in the world. It is rated as a class 10,000 cleanroom, which means that there are no more than 10,000 particles per cubic centimeter in the air. Apparently this is extremely good for a room this size. All of the parts in the Hubble are assembled there.

Next week, we are going to design our own controller for the Wien filter we are using, because the one the company provides draws too much current for our power supplies. We will also be trying to make what is called a microchannel plate working, because it is a much better ion detector than what we are currently using. Other than that, I will be spending a lot of time in the lab trying to get things working properly, which I like doing, so next week should be a fun one.

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Week of June 16, 2006

Well this week was a lot of fun. I got a good amount of experience with lab work, instead of just theory and modeling, and so far I like it a lot. Monday, I did spend most of my time modeling what we are calling the "wiggler," which puts a wiggle in an ion beam to get rid of everything but ions, and trying to get it to work properly. Also, I learned a bit more about why we are trying to make a neutral atom beam, and how neutral atom detectors work.

Tuesday was probably the most interesting day for me. I finally got to play with real ions instead of just computer simulated ones. The purpose of this was to get a mass spectrum of Nitrogen ions using a velocity filter (which we eventually did). It was really interesting finding out how everything involved in making an ion beam works. Before last week, I had never even heard the phrase "ion optics," but I have grown to like the subject a lot.

Wednesday, I spent all day modeling the entire ion beam chamber, including all current and current and planned elements. When I did this, I realized that the wiggler that I had designed was too big for where we had to put it, and since it was my first time designing anything like this, it wasn't very good anyway, so I completely redesigned it and now it works better and fits.

The spectrum that we got on Tuesday was not a little weird, and didn't really agree with my simulations, and Thursday we figured out a couple of things that we had done wrong, so we tried again. This time we got much better results which agree with the simulation, and make more sense.

Today, I got to see inside the ion beam chamber because we had to add something to it. This is when I had the wonderful experience of unbolting a piece of the chamber, and bolting it back on. The unbolting wasn't that bad, but it took a good thirty minutes to put this little piece of metal back on. I also spent a good while talking with Fred, my mentor for the internship, about what we will be doing next, and it sound like I will be in the lab a lot, so I am excited to start again next week.

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Week of June 9, 2006
This week I started my internship at NASA GSFC (Goddard Space Flight Center), and so far it has been a very fun experience. Monday was orientation day, so we toured the ACP building and met many people there, then I went to see where I would be working at GSFC, and meet the people I would be working with. My mentor for the internship was busy that day, so I didn't get to meet him then, but I met the other two people that I have been working with a lot since.

At NASA, I learned that I will be spending most of my time helping to make a neutral atom beam to test the newest neutral atom detectors they are currently making. Actually, I will mostly be trying to make it possible to have the beam consist of only one type of atom at a time. Also, I spent all of Tuesday, and a low of Wednesday figuring out a modeling program so we can come up with workable designs before trying to actually make them.

On Wednesday, I also went to a Senate hearing about NASA appropriation for next year. This was an extremely interesting experience, although everyone there had the same opinion about NASA appropriations, so there wasn't as much arguing as I would have liked to have seen. None the less, it was very fun, and it also gave me some time to wander around Capital Hill before the CNSF event that evening. So far, I have had a lot of fun, and can't wait to see what else will happen.

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