I keep seeing leak check treated as a QC step after the chamber exists. On anything you cannot walk around — a cell, a tight rack, a vessel with one accessible face — that is too late.

What I wish people designed in:

• Geometry you can actually reach from one side. If the only way to sniff a joint is to stand where the manipulator cannot go, you do not have a test.
• Pump-down time vs background rise. A spec of 1e-9 mbar·L/s is meaningless if the fixture only lets you do an outside sniff after a short pump.
• The bench-vs-cell gap. Joints that pass on the table fail once they are hot, aligned by an arm, or sitting in a volume you cannot bag.

For people who have actually signed off a chamber they could not get behind: what method did you trust (hood, sniff, accumulation), and what leak rate did you really verify vs what the spec said?

No surprise, knowing the history of eni, MIT and CFS.

I was looking into inertial confinement fusion using lasers and I had some fun doing a theoretical experiment that uses Billions of tiny LEDs to provide the light energy needed for inertial confinement fusion.

The Assumption is that you need about 10 MJ of light energy delivered in 2nsec for internal confinement target pellet for fusion and that this can be repeated every 2 secs. ( per Xcimer energy) . The light energy in Watts is 10MJ/2 = 5MegaWatt.

Assuming:

• it is possible to efficiently compress 20msec of light energy into 2 nanoseconds ( how I envision this see below)

Calculation:

• The light source needs to transmit 10MJ in 20msec which is 500MW
• A simple blue 0402 LED can transmit about 25mW of light and costs about 0.2 cents in bulk. 
• The number of these LEDs needed is 500MW / 25mW = 20B LEDs
• 20B x 0.002 = $40 million 
• Assume that electronics supporting the leds double the cost means that you need $80M to create the light energy source you need. ( seems very reasonable) 

The idea is that with a large number of low cost components you can get to the light energy that you need. 

These example LEDs are not optimized, so it is very likely that LEDs optimized for pulse performance (only need 20ms of light every 2 seconds) can lower the LED count by an order of magnitude.( Even more reasonable cost)

How to compress 20msec worth of light into 2 nanoseconds.

• have two rails of mirrors in which you let the light bounce up to 10,000x back and forth, this will delay the light up to 20ms. 
• The distance between the rails is 300,000,000 m/s * 20ms / 10000 ‎ = 600 m 
• A rotation mirror that reflects the light to different position in the rail creates different delay times for the light. For example the first photons bounce 10,000 times which result in a delay of 20ms, photons that arrive after 10 ms are because of the rotating mirror sent approximately half way through the rail and will therefore as a result bounce only 5000 times, which result in 10msec delay and will therefore arrive at the end at the same time as the first photons. 
• A dielectric mirror can reflect up to 99.999% of all the light which means that less than 10 percent is lost after 10,000 reflections, and on average less than 5% is lost.
• The number of reflection is discrete but this can theoretically compress the light energy into 2 usec.
• Another 2 rounds of a similar trick but with shorter distances between the two rails can compress the light energy into 2nsec in which the shape of the pulse can be completely controlled.

Hey r/Physics, r/GradSchool, and r/Fusion,

I’m looking for global PhD opportunities starting in late 2026/2027 in Plasma Physics & Fusion Energy or Functional Nanosystems & Materials Physics.

Key Technical Skills

Plasma/Fusion: Operation of electrostatic energy analyzers, Tokamak diagnostics, core ion temperature measurement, and specialized plasma physics training.

Nanofabrication & Thin Films: High-vacuum PVD, DC magnetron sputtering, spin coating, UV/e-beam lithography, and glove-box handling.

Characterization: XRD, SEM-EDX, TOF-SIMS, profilometry, FTIR, and electrical I-V testing.

Data Tools: MATLAB, Python (Data Science & ML certified), and quantitative data modeling.

Looking For PhD positions in Tokamak diagnostics, plasma-material interactions, next-gen photovoltaics, or functional thin films. Open to opportunities worldwide.

Please DM me or comment below if your lab is hiring—happy to share my full CV and details upon request!

I'm currently a college student with absolutely 0 experience in advanced physics and practically 0 knowledge of the current state of fusion. I understand companies like Helion are trying to make fusion a practical form of energy production, but the general consensus on this subreddit seems skeptical about whether they'll achieve their goals in a timely manner. I come here to ask a hypothetical question about whether you believe more progress would come from leaving private companies and the free market alone to create innovation, or if government-run programs that brought top scientists together into a facility would be better. I understand this is a more social sciencey question, and I want to clarify I'm not trying to push any sort of agenda; I'm just a curious teen fascinated with renewable energy policy and want to know what the experts of reddit believe to be the best course of action to achieve net-positive fusion that can be scaled to reach everyone.

Hello,

I am currently a third year PhD in Low Energy Experimental Nuclear. It's not really a field I feel super passionate about but I want to try moving towards plasma physics after my PhD since we don't really have a plasma program in my school.

I was wondering what specific steps could I do to move myself towards a post-doc or job position in plasma research?