Subject: Re: Hohlraum modeling paper - re-resubmitted to P.o.P.
From: Otto Landen <landen1@llnl.gov>
Date: Sun, 9 Oct 2005 19:02:58 -0700
To: "David H. Cohen" <dcohen1@swarthmore.edu>
CC: "Joseph J. MacFarlane" <jjm@prism-cs.com>, dcohen1@swarthmore.edu

David,

Reread again; if you do get to have another crack at it, I would suggest following tweaks:

Page 1 and 14:  Half-raum

Thanks. Got it (not relevant for the manuscript version, though).

Page 5:  I don't understand significance of comment on increasing C.E. to 0.69 so simulated Hohlraum Tr can match measured Dante Tr, which is apples to oranges comparison?

The context is the Decker paper - does DANTE provide a "surrogate" measure for (sample/hohlraum) Trad? At this point in the paper, we've shown that an analytic power balance formula gives a Thohlraum that is quite consistent with Trad on samples within the hohlraum (as calculated by visrad, using the same XCE as we used in the power balance treatment). But Tdante > Tsample (according to visrad).  And the analytic power balance treatment has been shown to reproduce the "measured hohlraum temperature" with values of xce ~ 0.7, but in these cases, the measurement is a DANTE measurement.  So... it seems to me that things hang together - analytic formula agrees with Tsample, as we'd expect.  But Tdante > Tsample, so how can (as has been claimed/shown) the analytic treatment also agree with Dante measurements?  It can by assuming a higher xce.   

What do you think? 

Page 6:  If space still an issue, could remove Fig. 6 and just say before Fig. 7 (which has quantitative info anyway) that Dante has no view of capsule.

I don't think it's an issue anymore...and I like Fig. 6. 

Page 9: "...one sees similar trends, with the only difference being that the low angle beams partially hit the back..."

Done. 

Page 10: I am suspicious of why the 100 ps data of Figure 13 shows Dante Tr less than sample Tr?  It almost seems like 100 ps sample Tr points are 5-10 eV too high (bit higher than case without LEH shown in Fig. 12 which seems odd)?

Actually, the sample Tr at 100 ps is slightly lower in the no-lip, Fig. 13 case than in the lip case, Fig. 12: 

pointing    lip    no-lip
335        129.7   128.6
485        134.2   133.7
635        137.2   136.7
785        136.7   135.4

I think that the flatness of the Dante-temperature-with-pointing-trend in the no-lip case comes from the fact that as the pointing moves in, the relative fraction of hot spots to wall doesn't change much (primarily because the lip doesn't occlude hot spots in the shallowest pointing).  And the overall low dante temperatures in the no-lip case arise from the significant view factor of the end of the barrel nearest the LEH, which is quite cold.  

I've put together a small comparison of the simulations - let me know what you think.  It's at: http://astro.swarthmore.edu/~cohen/projects/hohlraum/resubmitted_v3/lip_vs_nolip.ppt (or .pdf). I could also generate views from the sample position.  Let me know if you'd like to see that (or some other calculation results). 

This was the sort of thing, by the way, that made me want to include more of the temperature color map figures in the paper. 

Page 11: ".. in the longer halfraums is partially offset..."

Done. 

Page 13:  "...blocking much (some) of the LEHs seen by a sample (hot spots), decreasing...and preventing some of the radiation losses..."

Done. 

I would add after "...16% in flux.  As expected, the boost at the midplane wall is significantly smaller (2 eV or 4% in flux) as it the same unobstructed view of the LEH with or without the shield."

Done. 

Nino