This information pertains to the Plasma Physics program, which is separate from the Physics department. I have decided to go there this fall, so I will come back later with more information after I start, but I wanted to give a few general aspects of the program that made me want to go there without even visiting any of my other options.
The program's website is: http://w3.pppl.gov/gradprogram/index.html
And the PPPL's website is: http://www.pppl.gov/
Firstly, my primary research interest was fusion. Princeton’s plasma program is the top in the nation, according to,http://grad-schools.usnews.rankingsandreviews.com/grad/phy/plasma_phy
and much of the research happening there pertains directly to fusion (though there are plenty of projects focusing on other applications, or basic plasma physics, or astrophysical phenomena). The program’s headquarters are right inside the PPPL, a government lab a few miles away from the main campus. Thus, as a student at PPPL, you have infinitely more resources here than you would in a small lab at any university plasma program. There’s no competition for advisors or scarcity of student funding, since there are about 100 scientists working there who have the credentials to bring students into their projects, but there are at most 8 students per year enroll into the program. They could handle far more students than they have, but the graduate school sets limits on the size of each department.
I think Princeton’s atmosphere beats that of any other leading school. The comfortable suburban neighborhood and its moderate climate (compared to Boston, NYC, where it’s busier and always 5-10 degrees colder) are especially nice. Also, the department is laid back and the plasma program doesn’t try to weed people out.
One great thing about the program is that you’re not forced to commit to theory or experiment right away. The first year, everyone works on an experimental project and the second year everyone does a theory project (there’s still flexibility, nonetheless). Getting experience with both will be especially valuable. Only after that do students decide which branch they wish to pursue for thesis work, and even the thesis can involve a mix of theory/experiment too.
Also, the financial packages are nice.
So if you like plasma/fusion, this should be enough justification to go to Princeton. Incoming students often, but not always, have plasma research background and often have done what I think is called the NUF summer program during their undergraduate years, so try to do that if you can, it may help. But it’s still possible to be accepted from a mediocre school without any prior plasma experience, as I was.
Also, keep in mind that small programs get a correspondingly small number of applications, so the strength and number applications, the number of students who choose to enroll, and hence the number sought the next year, can vary drastically from year to year. An old AIP handbook from 2001 said the average PGRE of admitted students that year was only 750ish. The 2007 book said that year's average was 82%ile and the lastest version reveals that our group had an average of 92.5%ile. So the point is, don't hesitate to apply if you think your app isn't as strong as it could be... you might have picked a lucky year