Feature/kt3 #23

Mateasek · 2021-11-10T07:24:20Z

This PR add model of KT3 diagnostic based on FibreOpticGroup. related to issue #18

Based on FibreOpticGroup. Allows user to generate a KT3A or KT3B models with sightline information or by using the Simple Access Layer to get sightline information from PPF data.

Shows how a KT3 model can be obtained using SAL. Shows the sigthlin trajectories in a poloidal plane. Shows impact of spot position corrections and differences between KT3A and KT3B sightlines.

…ure/kt3

vsnever

Thanks, @Mateasek, this PR is superb. I especially liked the feature that allows to adjust the LoS alignment when the view is obstructed by the structure. I have only a few comments and the main one is related to the rarely available PPFs used to read diagnostic parameters.

vsnever · 2021-11-14T22:21:16Z

cherab/jet/spectroscopy/kt3/kt3.py

+import numpy as np
+from math import sqrt, tan, radians
+
+from jet.data import sal


Replacing this with

from sal.client import SALClient ... sal = SALClient('https://sal.jet.uk')

will make the code more portable.

We should probably define the DEFAULT_SAL_SERVER. At the moment it is https://sal.jet.uk, but in the near future it will probably change to https://sal.jetdata.eu.

I think the version of sal from jet package is slightly different isn't it? At least according to what they say here. It seems like this is the SAL version to use for JET. Also, when the default server changes, it should automatically be changed in the jet package, shouldn't it? This way we wouldn't have to care. The same style is used also in the equilibrium loading. Am I missing something?

You are correct. My point is that with from jet.data import sal this code will run only at JET clusters. With from sal.client import SALClient you can run it from anywhere.

Edit
Of course, we need to replace other usages of jet.data if we want this module to be portable, but that is a separate issue.

Look like sal = SALClient('https://sal.jet.uk') requires authorization on JET Data Center nodes, while from jet.data import sal works without authorization because it's configured for https://sal.jetdata.eu, which is currently unavailable outside of the JDC.
Something like:

try: from jet.data import sal except ModuleNotFoundError: # use general SAL client outside of the JET computing infrastructure from sal.client import SALClient sal = SALClient('https://sal.jet.uk')

will be a better solution.

However, this problem is general for all JET diagnostics implemented in Cherab, and should probably be solved with

from cherab.jet import sal

So, please ignore my comments about this issue, I think it's OK to use from jet.data import sal for now.

@Mateasek pointed out that the JET version of the SAL client can be installed on local machines by following the instructions from https://data.jet.uk/guides/sal/downloads.html#sal-downloads-label. Thus, replacing jet.data.sal with a generic sal does not make cherab.jet more portable as I mistakenly thought.

vsnever · 2021-11-14T22:50:12Z

cherab/jet/spectroscopy/kt3/kt3.py

+# empirically determined point limiting the inner sightlines
+KT3_INNER_THRESHOLD = Point2D(3.0510967354232994, 2.0072688526617264)
+
+def kt3_from_data(spectrometer, origin_rz, spots_rz, min_wavelength, max_wavelength, spectral_bins, pixel_samples=1e3,


I would rename it to load_kt3_from_data() to match the naming of other load_some_diagnostic() functions in cherab.jet.

vsnever · 2021-11-14T23:49:37Z

cherab/jet/spectroscopy/kt3/kt3.py

+    if spectrometer.lower() in ("a", "kt3a"):
+        leaf_origin = "/pulse/{0:d}/ppf/signal/jetppf/t3af/rzor".format(int(pulse_number))
+        leaf_spot_tile5 = "/pulse/{0:d}/ppf/signal/jetppf/t3af/rzdv".format(int(pulse_number))
+        leaf_wave = "/pulse/{0:d}/ppf/signal/jetppf/t3af/wave".format(int(pulse_number))
+        spectrometer = "KT3A"
+    elif spectrometer.lower() in ("b", "kt3b"):
+        leaf_origin = "/pulse/{0:d}/ppf/signal/jetppf/t3bf/rzor".format(int(pulse_number))
+        leaf_spot_tile5 = "/pulse/{0:d}/ppf/signal/jetppf/t3bf/rzdv".format(int(pulse_number))
+        leaf_wave = "/pulse/{0:d}/ppf/signal/jetppf/t3bf/wave".format(int(pulse_number))
+        spectrometer = "KT3B"


Unfortunately, these PPFs are produced on-demand. Among the 19500 pulses between 80124 and 99624, the T3AF and T3BF PPFs are available only in 33 and 290 pulses, respectively. Therefore, it would be nice to have some fallback values for origin_rz, spots_rz and wave.

Looks like the origin_rz (the first mirror position) is fixed at (3.28422, 3.56166) for all the ILW pulses. So, the problem is to obtain spots_rz and wave. I think that the wave can be obtained from the settings specified in the JPF using the equation for the dispersion of the Czerny-Turner spectrometer.

I see three possible solutions for spots_rz:

Calling kt3a(b)_los_siw_new() from home/cxs/instrument_data/kt3_common/alignment through idlbridge.

Implementing the parts of the kt3a(b)_los_siw_new(), agm_image_to_divertor() and agm_divertor_mark2() in python.

Hardcoding the {pulse1: spots_rz1, pulse2: spots_rz2, ...} dictionaries, in which the spots_rz1 is valid between the pulses pulse1 and pulse2.

The first solution is not portable. The second one requires some efforts and can only be implemented with the permission of Andy Meigs. My guess is that the rz_spots rarely changes, so the third solution might work. I'll check it out.

Thanks for pointing this out @vsnever . I didn't notice because the shot ensemble I'm working with. I will contact Andy Meigs to discus with him what could be the best way forward, but for myself:

Would cause a lot of problems to a lot of people and as you said it would not work remotely. I think this is not an option.

This would be the best solution in my opinion. Or getting the data from other files, we will see.

Having a default data would be a last resort solution.

I will inform here when I get some information.

I'm currently working on the 3rd solution by obtaining the values of spots_rz using kt3a(b)_los_siw_new() for the entire set of ILW pulses. So far I have found that spots_rz depends on the grating, which varies from pulse to pulse, but can only take on 3 values: 300, 1200 and 2400, while for the same grating, the spots_rz changes very rarely.

Lets wait for Andy Meigs before we jump to reverse engineering.

vsnever · 2021-11-14T23:56:25Z

cherab/jet/spectroscopy/kt3/kt3.py

+
+    return group
+
+def kt3_from_sal(spectrometer, pulse_number,min_wavelength=None, max_wavelength=None, spectral_bins=None,


Looks like this is a default way of loading the diagnostic, so the name load_kt3() would do better I think.

vsnever · 2021-11-15T00:05:24Z

cherab/jet/spectroscopy/kt3/kt3.py

+    return group
+
+def kt3_from_sal(spectrometer, pulse_number,min_wavelength=None, max_wavelength=None, spectral_bins=None,
+                 spot_position_correction=True, pulse_time=None, time_selection="nearest",


I would change the default value for spot_position_correction to False. The private PPF required for the spot correction may not be available.

Changed names to match package convention, changed default value of spot_position_correction to False

Mateasek added 4 commits November 10, 2021 08:17

Add KT3 diagnostic model

827d7e3

Based on FibreOpticGroup. Allows user to generate a KT3A or KT3B models with sightline information or by using the Simple Access Layer to get sightline information from PPF data.

Add kt3 init file

f5b7fff

Add KT3 demo

06a6eec

Shows how a KT3 model can be obtained using SAL. Shows the sigthlin trajectories in a poloidal plane. Shows impact of spot position corrections and differences between KT3A and KT3B sightlines.

Merge branch 'development' of https://github.com/cherab/jet into feat…

07180f0

…ure/kt3

vsnever reviewed Nov 15, 2021

View reviewed changes

change function names and default values

c4fe115

Changed names to match package convention, changed default value of spot_position_correction to False

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Feature/kt3 #23

Feature/kt3 #23

Mateasek commented Nov 10, 2021

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Mateasek Nov 16, 2021

vsnever Nov 16, 2021 •

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		return group

		def kt3_from_sal(spectrometer, pulse_number,min_wavelength=None, max_wavelength=None, spectral_bins=None,

Feature/kt3 #23

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Feature/kt3 #23

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vsnever Nov 16, 2021 •

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