# Superconductor: What form of paramters (like London penetration depth) to use?

I am dealing with thin film and LN2 temperature, and am trying to calculate values such as the Pearl Length, but am trying to find clarification as to which value of $\lambda_L$ to use in this case. e.g.

$\lambda_L(t,T)$ with T = 0 or T = 77K?

I have other formula, such as the kinetic inductance for a CPW, but the articles I am pulling them from are somewhat unclear which forms of the parameters they are using. Any help is appreciated.

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CPW = Co-Planar Waveguide? –  Qmechanic Apr 22 '13 at 7:37

Well LN2 boils at 77K - If you want the penetration depth at LN2 temperatures, use T=77K

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This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. –  Sklivvz Dec 9 '12 at 12:03
I did answer his question (as I understood it). He asks what his temperature parameter should be for calculating the penetration depth, 0K or 77K. Since he is at LN2 temperatures, he should use 77K ... –  Brendan Dec 9 '12 at 16:14
@Sklivvz Yes, Brendan answered correctly the question. The temperature of the bath will be the temperature of melting of the nitrogen liquid. –  FraSchelle Jun 21 '13 at 9:05
@Oaoa sure, but the answer does not explain anything. –  Sklivvz Jun 21 '13 at 9:10
@Sklivvz Ah ok, I get your point, and I agree. But the question was really precise, not of a general perspective. So the answer is really precise as well :-) If the OP wants a better answer, (s)he can precise her/his mind. (S)He refers to some articles without citations for instance... I think the Brendan answer is the best regarding to the details the OP gave. –  FraSchelle Jun 21 '13 at 9:39