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Want to try with the other propellants than which are given in the document #142

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krishna123-murali opened this issue Sep 30, 2024 · 35 comments
Closed

Want to try with the other propellants than which are given in the document #142

krishna123-murali opened this issue Sep 30, 2024 · 35 comments

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@krishna123-murali
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Hi, I tried simulating in HallThruster.jl with a molecular propellant. But, no ionization rate is seen in my plots (it's basically zero). can you help in resolving this issue? And if possible, could you let me know what all the things I should consider changing the code, if I am trying with new propellant?
@archermarx
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Hi,

Could you post your code, or at least a minimum working example showing the problem?

@krishna123-murali
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Hi,

Could you post your code, or at least a minimum working example showing the problem?

Hi, thanks for the reply.
I used the tutorial code to simulate it with Neon as propellant.
Following are the results I obtained.
Neon_plot
no ionization rate. you can check the configuration I used
Neon_config = HallThruster.Config(
ncharge = 1,
discharge_voltage = 300u"V",
thruster = Neon_thruster,
domain = (0.0u"cm", 4.0u"cm"),
anode_mass_flow_rate = 1.0u"mg/s",
wall_loss_model = HallThruster.WallSheath(HallThruster.BoronNitride),
anom_model = HallThruster.MultiLogBohm([0.02, 0.03, 0.04, 0.06, 0.006, 0.2]),
propellant = Neon,
neutral_velocity = 280.0u"m/s",
neutral_temperature = 300.0u"K",
ion_temperature = 500.0u"K",
cathode_Te = 2.5u"eV",
anode_Te = 2.5u"eV",
ion_wall_losses = true,
).
Please let me know anything else I can provide from my side thank you

@archermarx
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Hi!

So the issue with Neon is that there are no reaction rate coefficients implemented for it. You can see these files here:
https://github.com/UM-PEPL/HallThruster.jl/tree/main/reactions

To use a propellant, you will need to supply your own reaction rate files. Otherwise, no ionization will be able to occur. If you have those files, you should be able to use non-built-in propellants without any modifications to the code.

Molecular propellants are at the moment not well-supported. I will probably be working to add more support for them in the coming months, depending on funding, but at the moment you would only be able to do ionization, not any dissociation or recombination.

@krishna123-murali
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Hi!

So the issue with Neon is that there are no reaction rate coefficients implemented for it. You can see these files here: https://github.com/UM-PEPL/HallThruster.jl/tree/main/reactions

To use a propellant, you will need to supply your own reaction rate files. Otherwise, no ionization will be able to occur. If you have those files, you should be able to use non-built-in propellants without any modifications to the code.

Molecular propellants are at the moment not well-supported. I will probably be working to add more support for them in the coming months, depending on funding, but at the moment you would only be able to do ionization, not any dissociation or recombination.

hi,
I actually added the reaction rate files before I started the simulation, still the problem persists

@archermarx
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archermarx commented Sep 30, 2024 via email

@krishna123-murali
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sure,
For Neon elastic, I named the file as elastic_Ne.dat
Energy (eV) Rate coefficient (m3/s)
0.0 0.0
0.000000e+0 1.610000e-21
1.000000e-2 3.140000e-21
3.000000e-2 4.420000e-21
5.000000e-2 5.350000e-21
1.000000e-1 7.070000e-21
3.000000e-1 1.110000e-20
5.000000e-1 1.330000e-20
6.000000e-1 1.420000e-20
7.000000e-1 1.480000e-20
8.000000e-1 1.540000e-20
1.000000e+0 1.620000e-20
1.200000e+0 1.690000e-20
1.500000e+0 1.750000e-20
2.000000e+0 1.830000e-20
3.000000e+0 1.920000e-20
4.000000e+0 1.990000e-20
5.000000e+0 2.070000e-20
6.000000e+0 2.140000e-20
8.000000e+0 2.270000e-20
1.000000e+1 2.420000e-20
1.200000e+1 2.540000e-20
1.500000e+1 2.730000e-20
2.000000e+1 2.930000e-20
2.500000e+1 2.950000e-20
3.000000e+1 2.910000e-20
4.000000e+1 2.740000e-20
5.000000e+1 2.490000e-20
6.000000e+1 2.230000e-20
8.000000e+1 1.800000e-20
1.000000e+2 1.440000e-20
1.200000e+2 1.190000e-20
1.500000e+2 8.780000e-21
2.000000e+2 6.160000e-21
3.000000e+2 3.720000e-21
4.000000e+2 2.590000e-21
5.000000e+2 1.930000e-21
6.000000e+2 1.500000e-21
8.000000e+2 1.010000e-21
1.000000e+3 7.210000e-22
this is how I added for excitation and Ionization too..
I used,
using HallThruster: Gas
Neon = HallThruster.Gas("Neon", "Ne"; γ = 5/3, M = 20.1797) these to initiate in the code

@archermarx
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archermarx commented Sep 30, 2024 via email

@krishna123-murali
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In the reactions folder,
https://github.com/UM-PEPL/HallThruster.jl/tree/main/reactions

@archermarx
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archermarx commented Sep 30, 2024 via email

@archermarx
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Could you share just the ionization rates file you used?

@krishna123-murali
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sure,
file named as ionization_Ne_Ne+.dat
Ionization energy (eV): 21.56
Energy (eV) Rate coefficient (m3/s)
2.156000e+1 0.000000e+0
2.200000e+1 3.255000e-23
2.300000e+1 1.460000e-22
2.500000e+1 3.800000e-22
2.700000e+1 6.316000e-22
2.900000e+1 8.884999e-22
3.100000e+1 1.152000e-21
3.300000e+1 1.416000e-21
3.600000e+1 1.795000e-21
4.000000e+1 2.278000e-21
4.500000e+1 2.824000e-21
5.000000e+1 3.378000e-21
5.500000e+1 3.915000e-21
6.000000e+1 4.355000e-21
6.500000e+1 4.768000e-21
7.000000e+1 5.137000e-21
7.500000e+1 5.472000e-21
8.000000e+1 5.771000e-21
8.500000e+1 6.044000e-21
9.000000e+1 6.281000e-21
9.500000e+1 6.492000e-21
1.000000e+2 6.668000e-21
1.100000e+2 7.002000e-21
1.200000e+2 7.249000e-21
1.300000e+2 7.425000e-21
1.400000e+2 7.565000e-21
1.500000e+2 7.724000e-21
1.750000e+2 7.812000e-21
2.000000e+2 7.812000e-21
4.000000e+2 6.316999e-21
6.000000e+2 5.249999e-21
8.000000e+2 4.468000e-21
1.000000e+3 3.970000e-21

@archermarx
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Thanks, and as a test, can you try just copying the default xenon file and naming it as if it's neon? This will help me determine if it's a file loading issue or a physics issue.

@krishna123-murali
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I tried doing it, this is the result I got...
Xe_copied_as_Ne
I just changed the file as neon

@archermarx
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archermarx commented Sep 30, 2024 via email

@krishna123-murali
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sure, thank you very much. Meantime let me try changing the electron temperature. If I find something I will get back to you.

@archermarx
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To alter how the simulation initializes, you can write a new initialize! function (see https://github.com/UM-PEPL/HallThruster.jl/blob/main/src/simulation/initialization.jl) for a new initialization type. I'm now also adding parameters to the DefaultInitialization struct to allow for electron temperatures to be manually specified.

@krishna123-murali
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Can you brief me on this. Due you want me to change the anode_Te and cathode T_e (or) do you want me to write new initialization function in the code?? Thank you

@archermarx
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Actually, if you wait a few minutes, I am making a change to the code to make some things easier.

@krishna123-murali
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sure thank you

@archermarx
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OK, I've just updated the code to v0.17.0. Now, you can do the following in your config:

config = Config(
    ...,
    initial_condition = DefaultInitialization(max_electron_temperature = 50),
    reaction_rate_directories = ["dir1", "dir2"]
)

The first change lets you specify a maximum initial electron temperature, while the second change makes it easier to tell the code where to find reactions. These directories will be searched in order before the code looks in the default directory.

@krishna123-murali
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but I am getting an error as defaultInitialization is not defined

@archermarx
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You'll need to do HallThruater.DefaultInitialization

@krishna123-murali
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got unsupported keyword argument "reaction_rate_directories". This is the error I am getting

@archermarx
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archermarx commented Oct 1, 2024 •
edited
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strange, can you double check that you're on v0.17.0? The following works for me:

cfg = HallThruster.Config(
       thruster = HallThruster.SPT_100,
       discharge_voltage = 200,
       domain = (0, 0.05),
       reaction_rate_directories = ["dir1", "dir2"],
       anode_mass_flow_rate = 5e-6,
       )

@krishna123-murali
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Hello,
I checked with the version, I am on V0.17.0.
Julia>HallThruster.DefaultInitialization
HallThruster.DefaultInitialization

julia>Neon_config = HallThruster.Config(
ncharge = 1,
discharge_voltage = 300u"V",
thruster = Neon_thruster,
domain = (0.0u"cm", 8.0u"cm"),
anode_mass_flow_rate = 8.0u"mg/s",
wall_loss_model = HallThruster.WallSheath(HallThruster.BNSiO2),
anom_model = HallThruster.MultiLogBohm([0.02, 0.03, 0.04, 0.06, 0.006, 0.2]),
propellant = Neon,
neutral_velocity = 500.0u"m/s",
neutral_temperature = 500.0u"K",
ion_temperature = 500.0u"K",
cathode_Te = 2.5u"eV",
anode_Te = 2.5u"eV",
ion_wall_losses = true,
initial_condition = DefaultInitialization(max_electron_temperature = 50),
reaction_rate_directories = ["dir1", "dir2"]
)
ERROR: UndefVarError: DefaultInitialization not defined
Stacktrace:
[1] top-level scope
@ REPL[13]:1
I tried doing this but the error persists. could you help me with this???

@archermarx
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archermarx commented Oct 3, 2024 via email

@krishna123-murali
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Thank you. It's working. I will update you if I get the ionization rate

@krishna123-murali
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Hello again, I have found something strange I have found simulating with Neon.
I tried simulating this for 1e-7s. Following is the data I got
Neon1
Now I have increased the duration = 5e-7s, Hence the data is as follows
Neon2
For duration= 1e-6s,
Neon3
For duration=1e-5,
Neon4
Here electron Velocity and electric fields become zero. Even potential is not stable
As I tried increasing the time duration @1e-3s, there is no ionization rate , or Electric field and electron velocity (which you can see in the picture below)
Neon5
I am confused why it is happening soo... please help me to know what the actual problem would be.

@archermarx
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The ionization rate coefficients you have are extremely low, about a million times smaller than krypton, for example. Where did you get them?

@krishna123-murali
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I have got them from lxcat database.
https://nl.lxcat.net/data/set_type.php

@archermarx
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archermarx commented Oct 7, 2024 •
edited
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Can't access right now but I suspect those are cross sections, not rate coefficients. You can use the (undocumented) HallThruster .compute_rate_coeffs function to integrate cross sections over a Maxwellian vdf to get rate coefficients. It's in this file at like 17: https://github.com/UM-PEPL/HallThruster.jl/blob/main/src/collisions/reactions.jl

You can alternatively use a more sophisticated tool like BOLSIG+ to do that calculation.

@krishna123-murali
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Sure Thank You

@archermarx
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Hi, just checking in. Were you able to resolve your issue?

@krishna123-murali
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Hi, yes the issue is resolved. Right now I am trying to simulate with different channel lengths. The answers are well satisfied. However, with molecular propellant, I was facing an issue as dissociation is not supported (as you mentioned earlier). Other than that, everything is working fine. If anything comes up I will reach out to you. Thank you

@archermarx
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Excellent, glad to hear. I may be implementing dissociation early next year, so stay tuned

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