Recent content by Benindelft

Interesting way to get short pulses... Can you take that much lower, into the picosec. regime for example? I can imagine that 'theoretically' you could end up making aribitarily sharp pulses...

Hi, Thanks for the explanation Pumblechook- (I just came back from vacation and read your message). If the open ended stub is capacitively coupled to ground then a displacement current should flow and presumably this current would be 90 off phase with the E field?

Well I read the microwaves101, and all seems to make sense but couldn't see the answer to my question in there? Surely someone knows the answer?

Thanks Berkeman I didn't get chance to read the web page yet but I will do it later today... Thanks Pumblechook, that's a start but what about an open ? You can in theory neglecting loses etc get the voltage to become infinite due to constructive interference. Essentially you make a...

Hi, Here's stupid question... Been trying to think about what happens to the current and the voltage when you add a stub, and somehow I expect that one must lag the other, but I have no physics to suggest this. Can anyone explain what's going on here? Thanks !

OK, I got the answer to my first bit and am pretty sure about the second - but this is an interesting bit of physics so any further discussion would also be fun. Question was: Can anyone explain exactly why in field emission you get Nottingham heating? As I understand it the answer is: The...

Hi, Can anyone explain exactly why in field emission you get Nottingham heating? I can understand that you get joule/ resistive heating that makes sense. I can understand that you get cooling, the electron leaves the metal there is a loss of energy. But why does it matter if it is above...

Thanks! that looks pretty clear to me now. BTW how do you get the equations to looks so nice? Is that info some where on this website?

[SOLVED] Fermi Dirac- missing something from Ashcroft derivation Homework Statement Deriving Fermi Dirac function following ashcroft all good up to equation 2.43 but then it does the folowing at 2.44 and I can't see how you reach 2.44. Homework Equations as (2.43) f_{i}^{N}= 1-...

I don't have anything in the calculations, but I am pretty sure that we get quite a strong local electric field enhancement, that's all good (as long as it doesn't blow up the tip). There might also be some plasmon enhancement I think (but really not sure , I read that tungsten doesn't have a...

I am doing some basic heat calculations about a CW laser illuminated tungsten tip (which should be used for photoemission) - I started to play with the tip geometry to try and find a way to get more flux Watts/metre^2 onto the tip without it melting. I found that after solving the 1d heat...

Am I right in thinking you are doing some laser heating here? if so you should look at the paper written by Bechtel "heating of solid targets with laser pulses" . Also check out the citations there are a lot of papers out there that solve this kind of problem