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Summer 2012 Blog - Animesh Mehrotra-Hajela

Animesh Mehrotra-Hajela is spending twelve weeks in the Bay Area working at the Advanced Light Source of the Berkeley Lab.

 

June 1, 2012

The Beamline inside the ALS

My initial experiences at Lawrence Berkeley Laboratory have been very positive.  Over the past two weeks I have managed to learn a great deal about the work here at the Advanced Light Source (ALS). 

The ALS is quite a remarkable device that acts as an extremely high energy X-ray source.  It spins electrons to 99.9% the speed of light and then shoots them down tangential beamlines.  Beamlines, the tangential X-ray tubes, are where the experiments are conducted.  While a majority of the beamlines are for imaging extremely small materials, some particle accelerator physics studies do occur from time to time.  A vast majority of beamlines are also designed for imaging biological structures such as proteins and bone fragments. 

At our beamline, there are multiple projects running simultaneously.  One of the main projects that I work on, does not actually encapsulate use of the beamline.  Instead, I am working on MATLAB code to generate computer images (or simulations) of the sample, without actually imaging them.  This is important because access to facilities like the ALS is extremely limited.  Being able to model the X-Ray images without needing a high energy X-Ray source is the focus of numerous studies.  We want to be able to develop accurate images by simply inputting the dimensions and some unique characteristics of the material.  This unfortunately, is easier said than done.

Even while I consider myself to have a solid MATLAB foundation, I initially struggled to wrap my brain around the algorithms that would allow us to simulate X-Ray images.  Since Fourier Transforms are a major part of our work, I spent my first couple days just trying to understand what they do and how they work.  On the plus side, I did learn numerous of new things that I am excited to implement over the coming weeks.  I feel like I am well oriented at this point to accomplish the goal set for me at the beginning of the internship.

The view from my workstation.

So what’s the big picture?  The culmination of all of the projects at Beamline 8.3.2 is to help image materials that can withstand very high temperatures.  If implemented in powerplants, these materials (such as silicon carbide) have the potential of revolutionizing thermodynamic efficiencies across the board.  Less heat will have to be added to the turbines for the same amount of output work.

Lastly, I have to admit that the Lawrence Berkeley Lab is an outstanding place to work.  The people here are friendly and the lab is extremely concerned about everyone’s safety.  The ALS is (for a scientist) the ideal work place, as he/she can walk in, run an experiment, and then have access to an outstanding workstation to analyze data.  Furthermore, the views from the offices are phenomenal.  One rarely gets stressed working here, even when things don’t work as intended. 

 
June 9, 2012

After working at the ALS for several weeks now, the broad scope of the research conducted impresses me greatly.  Within our own research group of no more than 10 people, we are currently working on almost 8 different projects.  This raises a bigger question:  What then is the relevance of all of this - what ties these numerous projects together?  The answer is simple: energy.

The Berkeley National Lab has started a "Carbon Cycle 2.0" initiative in which most Department of Energy (DoE) research has to be working towards an energy efficient solution, one that goes hand in hand with the CC2.0 initiative.  All projects are working towards more energy efficient solutions, whether that lies in new materials or new processes

My work lies mainly in imaging materials such as bone, glass, and some ceramics.  While imaging is not directly energy related, the goal is to make these new-engineered materials have properties such that they can be implemented in a power generation process - in a power plant or even an automobile or aircraft engine.  In order to discover these essential properties, one must be able to view their microstructure to understand how the material performs under variable conditions.

My current efforts are devoted to simulating silicon carbide fibers (SIC), as these are greatly vital to producing high temperature turbines for use in power plants.  The goal is to get these ceramics imaged so we can understand their mechanical properties when loaded or heated.  SiC is supposed to mechanically robust up to 1800C - a temperature great enough to almost vastly improve the efficient of a power plant.

Power plant turbines, which run hotter, can expel more work for the same amount of heat. As a result being able to use robust ceramics that can mechanically withstand high temperatures allows scientists to develop very high temperature turbines - allowing for greater efficiency.  

 

July 23, 2012

At the beginning of my internship,  I started out simulating images made of “theoretical glass,” and have since moved on to theoretical glass cylinders bundled together.  These cylinders are meant to simulate Silicon Carbide fibers, also used in advanced materials and high temperature turbines, as mentioned in my earlier blogs. 

Part of my job was to understand the simulation code as much as possible, and then try and extrapolate the similarities, differences, and correlations between two different tools, both designed to complete the same task.   The end goal for this “micro-project” is to help another intern automate the process of reconstructing images taken from the ALS into 3D volumes that can be viewed on the computer.  Often times, a scientist at the ALS may not exactly know the material properties of his or her sample.  The sample may be an incredibly complex material, made up of thousands of different elements and organic molecules.  Coming up with precise material data is difficult, if not impossible for such materials.  This is why it is so important to learn how the results of an experiment change as the independent variables of the experiment change.  For example, for mystery material Y, one may simply change the distance from the X-Rays, change some other user-defined parameters, and then use my algorithm to come up with the material specs.  While this task is tedious and far fetched, the mathematical nature of X-Ray tomography allows this to be done with some simple calculations and extrapolations.  I am excited to present some of my results at the end of internship poster session in September.

 

August 6, 2012

Sample of oil droplet recon
Actual oil droplet

Although this is the last week of my internship with Cal Energy Corps, it seems that I have been assigned one more task to complete.  In addition to preparing my poster for the presentation in September, I have been tasked with reproducing oil droplet X-Ray images taken from a previously authored paper.  The task, while fairly straight forward, requires some data interpolation to determine the exact index of refraction of the unknown oil.  This can only be completed by doing multiple iterations by trial and error.  I hope that I can finish the task before leaving on Friday, as we have to present it in a talk; namely, during the visit of one of the authors of the aforementioned paper.  We are excited to present the phase simulation work we have done in MATLAB to reproduce images by simply using the mathematical equations of optics, and completely bypassing the X-Ray source.  While still in its infancy, this is a promising development in the field of X-Ray Tomorgraphy, one that I can say I am proud to have been part of.   

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