CCLDAS

Lunar Dust Returns Home (sort of)

noreply@blogger.com (rattfink138) — Wed, 17 Oct 2012 17:30:00 +0000

(February 11, 2012) After over 16 years of experiments, awe, and admiration, our Apollo 17 lunar dust, generously loaned to us by the wonderful people at NASA, is on its way home (to NASA, that is, not the moon). Every time this lunar soil came out of the safety of its hiding place, a crowd inevitably gathered. Always so much ado for such a little pile of dirt! In our defense, how many people can say they have handled, or even looked at a real piece of the moon, besides in a museum or through a telescope. Lunar material is so rare and scarce that there is an entire industry dedicated to creating lunar simulants. In fact, we have buckets of lunar and martian simulants, but nothing beats the real thing!

Update: Forgot to add in, this is what the dust looks like up close! (ShuA2)

Actual lunar dust seen under a scanning electron microscope

High School Plasma Success!

noreply@blogger.com (Anonymous) — Wed, 08 Aug 2012 19:18:00 +0000

But wait! there's more! (from the highschoolers.)

So, despite the title of our last post, we youngins are here once again to celebrate having finally gotten the plasma generator in the student office to work, at least rudimentarily.

(our first plasma; isn't it cute?)

As evidenced by the above picture, and those below, we've managed to generate a reasonably bright plasma; however, it is not ideal because of the striations visible along the axis of the tube, which we will hopefully be able to correct before we try to make any measurements on the properties of the plasma. Our eventual goal will be to use the plasma generator and included langmuir probe to measure the density and temperature under various pressure and voltage conditions.

(the Langmuir probe which we use to measure plasma properties. Inside the tiny glass tube is an even smaller wire (which the camera won't focus on.)

For now however, we are happy to have overcome some of the challenges that have slowed our progress so far. Included among these set backs are the difficulty we had creating a proper seal between tube components with the original plastic gaskets and, ironically, a leaky leak valve. Neither of these problems were particularly difficult to solve but they both required ordering replacement parts, which cost us quite a bit of working time.

Finally however, we've gotten a working set-up; so listen my children and you will hear science-y details of our setup...here (ok, it's a bit of a lame rhyme.). Anyway, the method we're using to generate plasma consists of emitting electrons and establishing an electric field (along the axis of the tube) to accelerate the electrons until they hit a passing neutral atom, hopefully with enough energy to ionize said atom. This method has a few limiting factors, however. First, in order for the average free electron to have enough energy to reliably ionize the gas, they have to have some room to accelerate before colliding with atoms, meaning that the pressure (and therefore atom density) of the gas must be low. Second, not all gasses have the same breakdown voltage at the same pressure. To illustrate, we have a picture of the Paschen curves of several gasses, including atmospheric gasses and Argon, which we're using.

Taken from http://upload.wikimedia.org/wikipedia/commons/8/82/Paschen_Curves.PNG

As you can see, Argon (in red) has a much lower breakdown voltage on average than does Nitrogen, hence our use of Argon. The plot also illustrates the pressure dependence of breakdown voltage , which, for argon, has a minimum around .6 Torr cm; since our tube has a length of approximately 50cm, our ideal pressure is around 12 mTorr.

To generate free electrons we're using a thoriated tungsten filament (red circle & first close up), heated until almost white hot (~900 C). Then we use the anode on the right (green & second close up) to produce an electric field along the axis of the tube. Below that we have a pump to keep the pressure low (blue & third close up). On the left (yellow & fourth close up) we have our bank of power supplies; the black one provides power to the fillament (averaging about 15 amps) and the two grey ones produce the voltage between the tube anode and cathode. Lastly, we have a tank of argon (purple. two guesses which close up) and the replacement for the leak valve, to supply and regulate a flow of argon.

Overall setup. and a fan. which Keith paid 4 (thanks, Keith!).

Filament: shiny.

The anode is on the right.

Ye olde pump.

Power supplies. the left one is a beast.

The argon feed and tank. and a delightfully functional leak valve.

And now, as a reward for sitting through the science, it's time for some pretty pictures of glowing argon.

Final Intern Update

noreply@blogger.com (CCLDAS High School Interns) — Mon, 30 Jul 2012 16:59:00 +0000

We're wrapping up our summer jobs at CCLDAS. We would like to thank Andrew, Mihaly, Anthony, Paige, Anna, Evan, Addie, Tobin, Mark, Keith, Chris, and Spenser. This experience was truly invaluable and we all learned a lot.

Our last week at the lab was busy, as always. We began by helping install the UHV chamber in the beamline. First, we disconnected LEIL from the beamline and moved it aside. Next, we moved the UHV chamber into place, only to realize that the wheels put the chamber too high. We eventually removed the wheels from the UHV assembly in order to lower it to the correct height. The chamber is now properly in place and is currently in use for Andrew's neutral gas generation experiment. In the process of installing the new chamber, we learned tons about high vacuum systems. Andrew taught us about flange installation techniques, cryogenic pumping, chamber alignment, and more. Look below to see pictures of the installed UHV assembly!

The newly installed UHV chamber

To our chagrin, the dust particles never hit the target, suggesting a misalignment. However, after disassembling the beamline, we were able to determine that the alignment was actually correct. This has brought about many concerns for Andrew's experiment.

After the UHV was installed, we wrote a Matlab program for Paige. This program can be used to find peaks in the charge values recorded by the LeCroy oscilloscope for the Dust Coordinate Sensor, ultimately allowing us to determine a dust particle's position as it travels down the beamline.

We then made a program for Spenser's Database project, which provides an organizational platform for data taken for various accelerator experiments. Our program puts LeCroy waveforms into a LabView friendly format and posts them to the CCLDAS database.

As a bittersweet ending to the week, we had to say goodbye to our fellow high schoolers from the lunar rover LEGO® Mindstorms camp. They brought youthful energy to our workspace, and we will miss them as they continue on their journeys in high school. Check out their awesome Lunar rovers in action below!

Rovers navigate the obstacle course

We all enjoyed our time at the lab. Thanks again to everyone at CCLDAS!

Thanks!!!

High School Intern Update

noreply@blogger.com (CCLDAS High School Interns) — Wed, 18 Jul 2012 20:54:00 +0000

It’s been an interesting week for the high school intern team. We began by creating a successful NXT robot to navigate the course created for the resident summer camp, a 3-week Lego Mindstorms lunar rover challenge. You can see our robot tackle the course in the video below!

As you can see, we have kept ourselves busy with various coding projects:

Jordan modifying NXT code

Nick creating a Fourier series program

Sean solving a statistics coding challenge

Several weeks ago, the pyrex tube on the plasma machine shattered. Now that we received a replacement part, we have redirected our attention toward this project. Jordan and Nick designed a Plexiglas shield for safety, and Sean helped to install it.After that, we reassembled and evacuated the tube. Unfortunately, the O-Rings that we were using failed to create a viable seal, so we made new ones from sheet rubber. With the new ring in place, we got the tube down to 15 mTorr, but unfortunately the required breakdown voltage was too high for us to safely generate a plasma. The next day, we went at it again, but this time using Argon gas, since it has a lower breakdown voltage. However, this lead to a new problem. The leak valve on the Argon gas cylinder prevented us from lowering the tube pressure below 150 mTorr, so we are currently awaiting a new leak valve. We hope to begin experiments, using the LabView code that Emily has written, in the near future.

Working on the plasma tube

We have also been assisting students from Professor Scott Robertson’s lab with the stepper motors project. These motors will be used for both the LEIL table in the beamline, and Professor Robertson’s lunar wheel experiment. You can see our current setup in the picture below. Until next week…

The stepper motor setup

Focused Ion Beams

noreply@blogger.com (ShuA2) — Fri, 27 Apr 2012 23:24:00 +0000

Hi Everyone,

Platinum deposition and cutting of my name into a
Silicon wafer (notice the scale bar is 3 um)

0 degree view of a crater that has been cut for cross
section view.

A quick update, I just finished training to use the Focused Ion Beam yesterday so I am now fully capable of micro machining! You can do a lot of cool stuff like writing your name into a sample, marking a sample so you can find your targets again and more relevant to my thesis, cut craters in half and see the crater profile.

Platinum deposition helps to protect the sample you want to see a cross section of and helps to bring out the contours of craters. In parallel with this work, I'm working with Yancey Sechrest, another grad student working for Tobin on a plasma turbulence problem, to create a program that can take a stereo pair (2 images of the same crater at different angles) and recreate a 3D model of the crater. Hopefully I'll have a post soon with the results of that project

Shu

25 degree view of a crater that has been cut. The white stuff
is a layer of platinum deposited to make the crater edge more
visible.

Scanning Electron Microscope Pictures

noreply@blogger.com (ShuA2) — Mon, 23 Apr 2012 23:19:00 +0000

Hi Everyone,

Sorry again for taking so long. I've been away for a while (in Heidelberg, Germany playing with their accelerator) and working hard at getting scanning electron microscope (SEM) pictures of the craters I'm making with the accelerator. So without further ado, here's some of the pictures I've taken. I'm trying to get images of craters and then tilting the image to make a stereo pair and reconstructing a 3D model of the crater. Enjoy!

Embedded iron particle in Polyvinylidene Fluoride (PVDF)

Crater in PVDF

Also I'll be doing training to be able to use the Focused Ion Beam (FIB), which is essentially the same thing at the SEM but it can also cut samples and build up structures!

Image of a crater taken in a FIB

The same crater as above but with a cross section cut out

Shu

Beam Spot

noreply@blogger.com (ShuA2) — Thu, 22 Dec 2011 23:42:00 +0000

Hi Everyone,

Got to see an actual spark inside the Pelletron, what you
see are the grid lines from the Dust Coordinate Sensor

The beam spot as seen from an astronomy camera
inserted into the middle of the beamline

Sorry for the long time between posts. I'm trying to whip everyone in shape so they'll start blogging as well. A couple of really exciting things have happened since my last post. I've been working on determining why our accelerator speeds have only been up to about 10 km/s. In order to answer this question, I've been using a CCD camera typically used for taking long exposures of the night sky and putting into the path of the beamline before our detectors. Letting the dust hit a quartz target directly in front of this camera allows you to take images of the beam profile. With this we were able to figure out where the beam was pointed, what it looked like, and most importantly, how to point it in the direction we want to point it in.

We were able to determine that at our current running parameters, the beam's best focus creates a spot size of about 2 mm. By moving the back of the Pelletron we are able to steer the beam. Using a laser attached to the Pelletron we can steer the beam to very high accuracy. I was able to move the beam almost exactly 2 mm to the right and 3 mm down in that picture. With this capability we made sure the beam was pointed through the detectors and then starting taking data. The result of all that work? We know see particles up to about 45 km/s!

Shu

Beam Profile

noreply@blogger.com (ShuA2) — Wed, 14 Sep 2011 01:09:00 +0000

The focused spot of the beam profile. The Einzel focusing
lens will focus particles with a specific charge-to-mass ratio
into a beam as seen

Hi Everyone,

The halo of the beam profile. Due to the non-constant
charging process in the source, the charge-to-mass ratio of
each particle can vary greatly. This leads to this unfocused
halo around the focused spot.

We're still working hard over here at CCLDAS so unfortunately we've been neglecting the blog a little bit. Some updated info on the accelerator, we've finally got a preliminary image of what the beam actually looks like going down the accelerator. We put a window and foil as close to the source of the accelerator as we could and we ended up with these images of that foil. Unfortunately, as you can see, our beam is pretty defocused right now. Luckily we do expect a central beam plus a diffuse halo around it, which is what we see. The only problem is that we want that central beam to be more like 1mm than 15, so we've got a bit of work to do.

The reason for the central beam and the halo has to do with the way the dust source works. This particular source does not charge every particle the same, so the charge-to-mass ratio is not constant across all the particles. The focusing of the beam on the other hand, is dependent on the charge-to-mass ratio. What we would expect is that a majority of the particles will be charged to the same charge-to-mass ratio, giving you a well focused central beam, but then the rest of the particles will end up in the diffuse halo around the central focus.

I'll be continuing these studies into next week and hopefully will have more updates for you by then.

Shu

DPS ready for dust testing

noreply@blogger.com (Paige) — Wed, 10 Aug 2011 22:58:00 +0000

The dust position sensor (DPS) is finished and ready to give the position of its first dust particles during a test run in the small accelerator tomorrow. Similar to the dust trajectory sensor (DTS), DPS reads the pulses from induced charges on a grid of wires as a charged particle flies through. Comparing the pulses from each wire allows us to pinpoint the position of the particle. Unlike the DTS, the DPS is small enough to fit inside the beamline and can be placed in a number of locations.

LDEX flight model is here!!

noreply@blogger.com (rattfink138) — Thu, 04 Aug 2011 17:27:00 +0000

Exciting news, our first piece of flight hardware is now being calibrated in our dust accelerator. This gives us some serious clout in the dust and space community! A week or two ago we shot dust at the engineering model, which was cool, but this is the real deal! Sorry for the poor picture quality, there wasn't enough light.

noreply@blogger.com (ShuA2) — Wed, 03 Aug 2011 20:10:00 +0000

Hi Everyone,
I've been meaning to create a YouTube account for the lab for a while now and finally got around to it. This is a time lapse I made using images captured from the dustcam while we were building the accelerator. Whenever we get cool videos we'll be sure to post them to our account, TheCCLDAS. Hope you guys like it!
Shu

LDEX in CCLDAS Accelerator

noreply@blogger.com (ShuA2) — Tue, 05 Jul 2011 21:54:00 +0000

Hi Everyone,

LDEX in LEIL

David James and Keith Drake putting
LDEX into LEIL

It's been a while. I'll try to make sure we get more regular updates. In the meantime, something exciting happened recently, we have LDEX inside the LEIL target chamber and we were firing on it this past weekend (ugh yup, grad students don't get vacation...). They're still doing some tests on it while it's under vacuum, but will hopefully be done sometime this week.

LEIL under vacuum with the laser
shining onto it

The good news though is that the particle selection unit seems to be doing its job in selecting particles. We discovered, however, a bunch of particles still made it to LDEX despite the fact that they did not appear on our detectors.

For those who don't know, LDEX is the Lunar Dust EXperiment that will be flying aboard the Lunar Atmosphere and Dusty Environment Explorer (LADEE) mission in 2013. It can measure the charge and mass of dust particles and will hopefully enlighten us on the density of dusty plasma in the terminator regions of the moon.

Shu

More SEM Images

noreply@blogger.com (ShuA2) — Tue, 17 May 2011 23:26:00 +0000

Hi Everyone,

Here are some more cool SEM images of glass samples that we fired at. As you can see we've got some larger structure around the micron crater. Also, previous to this, I had only been able to find 3um craters which I thought was odd. I have now found craters on the submicron scale. These guys are really tough to find and image. I'll hopefully have more images and a couple more details on them in the near future.

Shu

Small crater <1um. These guys are really tough to image.

SEM image of dust damage on glass. Crater is about 2 um.

First Dust Impact Sites

noreply@blogger.com (ShuA2) — Fri, 06 May 2011 16:28:00 +0000

First dust impact, average diameter of 3.84 microns.

Hi Everyone,

We had our first customer come to the accelerator. Mr. Doug Currie from the University of Maryland was studying dust impacts on samples of polished fused silica glass to see what kind of damage micrometeorite impacts would do to the glass. After firing about 3000 shots onto a 1" diameter piece of glass, we took the sample to a scanning electron microscope (SEM). This is one of the craters we found on the surface. It has an average diameter of 3.84 microns. The dust we fired at it ranged from 0.4-6 microns in diameter and a velocity of 1-3 km/s. I'm hoping to get more time with the SEM and a good optical light microscope to get a better idea of what we did to the surface.

Shu

Future of Space Flight Symposium

noreply@blogger.com (ShuA2) — Mon, 25 Apr 2011 23:56:00 +0000

Hi everyone,
I apologize for the long hiatus, I've been working on my second comprehensive exam so I haven't had much time to blog. Coincidentally, on the 29th of April, we at CCLDAS will be hosting a public symposium on the Future of Commercial Space Flight. Check the flier above for details. If you can't make it, you can still watch the symposium by going to http://www.ustream.tv/channel/the-future-of-commercial-space-flight. Hope to see you all there!
Shu

Dust to the End!

noreply@blogger.com (rattfink138) — Wed, 20 Apr 2011 21:29:00 +0000

I am very pleased to announce that we successfully ran the accelerator today at 2MV with signals all the way to the last detector (great job with the alignment guys!). I have attached an image of one of the faster but typical signals. The blue is the first detector, red third, and the black is the final detector (we also used the second detector for a time but only have three power supplies at this point). Please enjoy the picture! Congrats everyone, this is another huge step!

noreply@blogger.com (rattfink138) — Tue, 25 Jan 2011 18:29:00 +0000

If you have been following, by now you know that our accelerator is up and running and very close to being finished. What you may not know it that all of this work could not have been completed without the dedicated work of Kurt Kapfhamer from NEC (it would have easily taken us months rather than weeks). Two weekends ago we took some time to show Kurt some of beautiful Colorado in Estes Park. We saw some elk, ate trout, and even walked on a frozen lake.Stay tuned for more updates!

Success!!

noreply@blogger.com (ShuA2) — Tue, 25 Jan 2011 01:12:00 +0000

Hi Everyone,

The Pelletron has been charged up to 3 million volts!

We did a bit more work on the Pelletron today, filling the tank all the way up to 80PSI of SF6. We also tried running up the voltage on the Pelletron and was able to get it up to 3 million volts! Unfortunately it started sparking at this point, which is normal. It sounds a bit like a gun but a little quieter. We've got it now at about 2.5 million volts and we'll be "conditioning" it all night. This really just means we'll leave it running and any of the rough edges or dust still left inside the high voltage terminal will be blasted away by the sparks that are created. With any luck, the Pelletron will be fully functioning tomorrow morning. Keep your fingers crossed!

Shu

It's Alive!!!

noreply@blogger.com (ShuA2) — Sun, 23 Jan 2011 19:42:00 +0000

Hey Everyone,

The Pelletron has been charged up to 1,437,000 volts!!!

Great news, we just tried turning on the Pelletron now that the vacuum tube is at vacuum and the tank is full of 60PSI of SF6. As you can see in the picture, we were able to get it up to about one and half million volts! It's a little on the noisy side, but it isn't too bad as long as you're a couple of feet away. We'll start actually conditioning it and do more thorough testing tomorrow and hopefully be up to 3 million volts before the end of the week.

Shu

Pelletron Status

noreply@blogger.com (ShuA2) — Thu, 20 Jan 2011 01:15:00 +0000

Hey Everyone,

So we've got quite a bit of the Pelletron wired up and the vacuum pumps have been attached. We'll be finishing up the wiring and then tomorrow we'll hopefully have the entire thing under vacuum and powered up. We were able to get the chain spinning so we at least have that going in the right direction. We'll be checking to see if the chain is properly charging tomorrow and hopefully be able to run the entire thing up to 3 million volts!

The Pelletron as of 1/19/11. It's wired
up (mostly) and the vacuum pumps are
attached!

A close up of the Pelletron chain.

The power box and the Pelletron in the background.
If you look at the chain, it looks like a solid metal piece because
it's actually spinning in the picture!

For those of you wondering, a Pelletron is a device similar to a Van der Graaf generator that creates a large electrical potential difference. The main difference between the two is that instead using a belt to pick up and move the charge from one side to the other, a chain made up of metal pellets connected by insulating nylon links is used. Also, the charge transfer occurs by induction preventing any spark damage or rubbing. These machines can generate potential differences up to and beyond 25 million volts.

If everything goes well, we'll be firing dust soon. Keep your fingers crossed!
Shu

The Pelletron Has Arrived!!!

noreply@blogger.com (ShuA2) — Fri, 14 Jan 2011 06:20:00 +0000

Hey everyone,

The Pelletron arriving at the lab in the back of a
truck still to be unloaded

Sorry for not posting much lately, it's been really busy in the lab. The Pelletron, the high voltage end of our accelerator, arrived yesterday so everyone's been really busy putting it together. We're all super excited that its finally here after about a year and a half of waiting. We can't wait to fire it up and shoot some dust.

The pelletron on its tracks next to the
gas tanks of SF6

We've already done a bunch of work on the pelletron and have the shell on its rails and the SF6 gas tanks in place. We're hoping to be able to get the head stand in place by tomorrow so we can start aligning the pelletron to the rest of the beamline. We took a bunch of pictures of the whole process of unloading it from the trucks and when we find time they'll all be on our flickr account. Also make sure to check our webcam from time to time to see how the progress is going. Both links can be found in the links section on the right side of the blog. We'll keep taking pictures of the whole process so you'll get to see all the exciting work going on right now.
Shu

New Interlock Control Box for CCLDAS

noreply@blogger.com (Spenser) — Fri, 07 Jan 2011 20:13:00 +0000

Yesterday, I finished work on a new interlock control box. It was designed and built here to provide localized control of several pneumatic gate valves along the CCLDAS beamline.

This box allows the valves that it is interfaced with to be easily controlled and monitored from one place, and can also automatically close valves connected to pressure-sensitive pumps in the event of a vacuum fault somewhere on the beamline. The system also has a capability to communicate with other components such as LIEL and the Pelletron.

Exciting Things Going on at CCLDAS

noreply@blogger.com (rattfink138) — Fri, 31 Dec 2010 22:27:00 +0000

Happy New Year!!

Even with most students out of town for winter break, work is feverishly going on as we await the arrival of the Pelletron (the business end of the dust accelerator) which will be arriving in early January. We have spent the last week finalizing the vacuum system by installing cryogenic pumps and other critical components (live progress can be seen here: http://dustcam.colorado.edu).

Meanwhile, I thought I would share some of the interesting pictures taken while operating the small accelerator (which is 1/150 the accelerating voltage of the big one). The first picture is our Star Trekesque warp drive which is used to accelerate our particles in and out of existence using principles of multi-dimensionality...

Okay, it is really just a look down one of our detectors which measures the velocity and charge of dust particles coming down the beamline... equally as cool as a warp drive! It uses sensitive electronics that can measure the image charge induced on the inner tube as the dust goes whizzing by at 100km/s.

These pictures show what happens when 20kV discharges in air. The images are from the back of the dust source where the dust is initially charged up and shoots through a pin-hole on the other side. The lightning is not supposed to happen, by the way.

When in operation on the big accelerator, these discharges won't occur since it will be surrounded by gas that prevents arcing. In the meantime we are working on ways of insulating the connectors.

DTS ready to go!

noreply@blogger.com (Unknown) — Wed, 29 Dec 2010 05:11:00 +0000

Hi everyone, for my first post, I will be sharing a little on the current status of the Electrostatic Lunar Dust Analyzer (ELDA). Shown in the picture, ELDA is consisted of a deflection region that is sandwiched between two DTS's.

The DTS's purpose is to detect both high speed interstellar as well as slow moving lunar dust. This is done through the use of charge sensitive amplifiers (CSA) made from off-the-shelf components. With four planes of wire grid, charge from a particle passing through can be recorded and analyzed for speed and trajectory. In conjunction, with the deflection region, the mass of the particle passing through the instrument can be calculated using the trajectories obtained before and after the deflection region.

The instrument is partially completed with all slow speed CSA mounted. It is in a standby status ready to be tested in the vacuum chamber at NPL. All that needs to be done now is making a platform for the instrument to rest upon in the chamber. More updates will follow!

AGU Fall Meeting 2010

noreply@blogger.com (ShuA2) — Thu, 16 Dec 2010 05:36:00 +0000

To give you an idea of the scope, this is about a quarter of
the poster hall. There's a total of about 2400 posters per day.

Hey everyone, most of the CCLDAS team is now at the American Geophysical Union's Fall Meeting. To give you an idea of the scope of this conference there were 14,000 attendees in 2007 (according to Wikipedia it's the largest annual scientific conference in the world). I've been cruising around the conference checking out posters and going to talks and its been very exhausting with the sheer amount of information that you get bombarded with at this conference (not to mention that it happens every year during finals week so I'm always sleep deprived from final projects and studying). There hasn't been a whole lot on the moon just yet at the conference, big day is tomorrow, there are talks all day on the moon, so I'll give an update on that after it happens.

Me in front of my poster with soda in hand ready to explain
how our accelerator works and what we're working on now.

On another note, I actually presented my poster today and there was a significant amount of interest in the dust accelerator. Usually people just want to know what a dust accelerator is so I only get to talk about the left third or so of my poster but this time there were a bunch of people who were also excited at the other things we've been doing, like signal filtering to get better accuracies in measurements. I was planning on standing by the poster for 2 hours at the conference and ended up talking for almost 4.5 hours straight! I'll make sure to take more photos as the conference goes on and they'll all be up on the flickr account sometime this or next week.
Shu