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#1 2018-09-28 21:13:48

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Ion Neutralization Propulsion

I've got a bit of a weird one for you all today, an idea I call "Ion Neutralization Propulsion".

I was thinking about orbital rockets.  The fundamental problem we have, the reason that going 300 km up is so much harder than driving 300 km north, south, east, or west, is energy.  Going upwards takes a lot more energy than going sideways, and the requirement to have a speed for a stable orbit adds much more.

Rockets are difficult to build, fundamentally, because the low energy content of chemical fuels means that rockets need to be giant fuel tanks, with extremely efficient machines composing a very small mass compared to the total system.  As a point of comparison, if you could get an Isp of 600 s you could achieve orbit with a mass ratio around 5.  At 800 s, your mass ratio is around 3.25.  At 1200 s it's 2.2, or you can start thinking about a full retropropulsive landing.

The best you can do with a chemical fuel is around 450 s in a vacuum, using H2/LOX.  H2/LOX has plenty of other drawbacks: Hydrogen has a very low density and it's deeply cryogenic, plus it has a nasty habit of exploding without warning in the gaseous state.  There's a couple fuels that do better than this such as a tripropellant engine using Lithium, Hydrogen, and Fluorine that has an Isp above 500 s.  Lithium and all its compounds are psychoactive mood stabilizers, while Hydrofluoric Acid is perhaps the most harmful of all the acids because of its ability to leech through skin and flesh.  As a resident of Planet Earth I think I'd rather take my chances with an NTR that blows up 1 in every 100 flights.

Anyway, we're in a range beyond what you can do with chemical reactions.  Nuclear reactions certainly have enough energy to go to orbit, but have other problems: Fission poses an inherent risk of losing containment, steady-state artificial fusion doesn't exist as a technology (even after tens of billions of dollars of research) and even if it did it wouldn't have the required energy density, and radioisotopes pose some loss-of-containment risks and also don't generate enough power per mass.

We're in a place where nuclear is problematic overkill (in the extreme case, Orion is easily capable of reaching orbit but also involves literally nuking your launch site and spreading radioactive waste across thousands of km) and chemical is simple and underpowered.  What we really need is something in between the two.

My benchmark for this is to find a fuel that can achieve at least 6 km/s.  Including an efficiency of 75%, that means the fuel needs to have an energy content around 25 MJ/kg or 0.25 eV/amu.

What I've come up with is the idea of trying to take advantage of ionization energies.  Basically, you heat up a gas until it's a plasma, use electric and magnetic fields to capture and store pure positive ions (H+, i.e. a proton, is the most basic example), and then when you're ready reintroduce electrons and use the energy produced to heat up some propellant and fuel your rocket.  Incidentally the simplest way to introduce electrons is probably to let your positive ions steal them from normal matter. Have a look at the following table with selected nuclei (All units: eV/amu):

EGEfiWz.png

(Data from CRC by way of this wiki article)

The upshot of this table is that the energies available from ion neutralization meet or exceed what you need to get substantially higher Isps.

The problem here is storage: This energy is released when an electron from the environment interacts with the positively charged ion.  Any contact with normal matter will cause a loss of containment, and given that there will be a substantial store of positive ions you'll also have problems with electric arcing.

I don't really know how to go about storing these ions, especially not how to go about storing them in a reasonably dense and stable manner.  Does anyone have any ideas?  What do you all think about the idea more generally?

I do know that it has substantial promise: Iron, if stripped of all its electrons, would be able to store 619 eV/amu, which works out to almost 60 GJ/kg.  If used directly as a fuel, with no propellant, you could theoretically achieve exhaust velocities as high as 350 km/s (35,000 s), or 0.1% of the speed of light.  This is the kind of fuel that could take a rocket from Earth to Mars in under a week (I'm thinking a 1 m/s^2 brachistochrone)


-Josh

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#2 2018-09-29 03:24:12

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,204
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Re: Ion Neutralization Propulsion

Hmmm. You mentioned this quite a few years ago, talking about Caesium.

Essentially you're talking about a capacitor, right? Positive charge in one area, negatively charged in another, energy released when the electrons are free to flow and neutralise the charge? Maybe you could get away with some kind of lattice, storing the positive ions in between negative electrons (that are somehow prevented from rejoining them...), to get an overall neutral charge (while lightning striking your spacecraft makes for awesome visuals, it's probably not good for it).


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#3 2018-09-29 07:12:31

Belter
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Registered: 2018-09-13
Posts: 184

Re: Ion Neutralization Propulsion

Batteries!  In!  Spaaaaaaaace!!!!!!!!

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#4 2018-09-29 08:06:07

tahanson43206
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Registered: 2018-04-27
Posts: 1,846

Re: Ion Neutralization Propulsion

This is my first post in NewMars, so if it works, I'd like to thank Mr. Burk and Daniel for solving a pesky problem with the registration process.

Josh, some time ago I ran across a paper that might be pertinent to your topic ... I was trying to learn about fusion experiments, and found a paper on a cylindrical ion storage device.  I'll try to find my notes later today, but in the mean time, if anyone else is inspired to look, my recollection is that the work resulted in a patent application, and possibly a patent.  The design employed rotation of the trapped ions in a magnetic field, which took advantage of the squeezing effect as charges move in the field.  The design (I think) evolved from study of large ion storage rings used for high energy physics experiments.

(th)

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#5 2018-09-29 12:09:11

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Ion Neutralization Propulsion

Terraformer wrote:

Hmmm. You mentioned this quite a few years ago, talking about Caesium.

I can't seem to find the thread, but I think the idea there was to find isotopes that decay via electron capture, then prevent them from doing so by stripping them of electrons. 

Essentially you're talking about a capacitor, right? Positive charge in one area, negatively charged in another, energy released when the electrons are free to flow and neutralise the charge? Maybe you could get away with some kind of lattice, storing the positive ions in between negative electrons (that are somehow prevented from rejoining them...), to get an overall neutral charge (while lightning striking your spacecraft makes for awesome visuals, it's probably not good for it).

I guess the idea is similar in a lot of ways to a capacitor, but instead of getting energy from bulk neutralization you're getting it from the neutralization of individual nuclei.  I guess if you're using protons most of your energy will probably come from normal capacitance effects, whereas if you're working with fully-ionized Iron it would be from ion neutralization.

tahanson43206 wrote:

This is my first post in NewMars, so if it works, I'd like to thank Mr. Burk and Daniel for solving a pesky problem with the registration process.

Josh, some time ago I ran across a paper that might be pertinent to your topic ... I was trying to learn about fusion experiments, and found a paper on a cylindrical ion storage device.  I'll try to find my notes later today, but in the mean time, if anyone else is inspired to look, my recollection is that the work resulted in a patent application, and possibly a patent.  The design employed rotation of the trapped ions in a magnetic field, which took advantage of the squeezing effect as charges move in the field.  The design (I think) evolved from study of large ion storage rings used for high energy physics experiments.

Hey tahanson, welcome to Newmars!

That paper sounds very interesting and relevant and if you can find it I'll definitely give it a read!


-Josh

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#6 2018-09-29 19:21:36

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,805

Re: Ion Neutralization Propulsion

This sounds simular as well when looking at matter to antimatter collisions to release large sums of energy.

As for the topic with the cesium or caesium posts I am thing that it was Americium that contained the information.
http://newmars.com/forums/viewtopic.php?id=7358

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#7 2018-09-30 12:43:02

tahanson43206
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Registered: 2018-04-27
Posts: 1,846

Re: Ion Neutralization Propulsion

For Josh and SpaceNut ...
It turned out I had a binder with notes on the "rotating wall" ion storage system.
The article is by Hollmann, Anderegg and C. F. Driscoll
UC San Diego
The copy I have is from Physics of Plasmas Vol 7, Number 7, July 2000
However, a direct link to the American Institue of Physics citations web site appears to be showing the same paper:
https://aip.scitation.org/doi/abs/10.1063/1.874128

The first correction I have to make to my recollection from 2010, is that the storage method uses electric fields, not magnetic ones.
However, I gather that magnetic forces are present because charges are moving. 

The density achieved for the experiments cited appears to be low, but it may be sufficient to demonstrate the feasibility of what I understand to be your idea.

The paper discusses electrons and ions in a section entitled: Torque from Driven Plasma modes

Extrapolating from what I understand of your idea, I can imagine a vehicle with pods to right and left of a central fuselage, dedicated to positively charged ions on one side, and electrons or perhaps negatively charged ions on the other side, with a propulsion device in the center.

Google listed multiple citations for E.M. Hollmann and for C.F. Driscol in 2010.

Amazons shows two books by Driscoll:
Pure Electron Plasmas Near Thermal Equilibrium1996
by C. F. Driscoll
Paperback
$105.00(1 used & new offers)
Transport in Nonneutral Plasmas
Transport in Nonneutral Plasmas1996
by C. F. Driscoll
Paperback
$105.00(1 used & new offers)

No books showed up for E.M. Hollmann
(th)

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#8 2018-10-04 14:40:20

JoshNH4H
Member
From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Ion Neutralization Propulsion

Very promising!  We would need confinement many orders of magnitude better but it seems like something of this sort should be possible if we really go for it.


-Josh

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#9 2018-10-04 20:49:06

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,846

Re: Ion Neutralization Propulsion

For Josh:

Thanks for taking a look at the ion "rotating wall" storage paper. 

Your observation that ion density is low, compared to the requirements for the propulsion system you've proposed, could be read as encouragement to see if the storage system can be improved.  I reread Post #1 of this topic, and noted the advantage of using iron as the working "fluid".

By coincidence, while searching for articles about GCR's, I found that iron is one of many elements which are stripped of electrons and launched into the cosmos by natural processes.  I note that a propulsion system that generated 1% of light speed iron packets would (presumably) show up as a GCR generator if a detector is downstream.

I was surprised to learn how much work is being done in study of GCR's and similar high energy moving particles.

Here is one system which uses detection of Cherenkov radiation to "observe" GCR (and other radiation) activity.
https://www.hawc-observatory.org/observatory/tanks.php

Elsewhere in the forum there has been discussion of use of water to protect space travelers from radiation.  It would seem from the HAWC example, that a pool of water would sparkle with Cherenkov radiation.  I recall reading that astronauts have reported observing flashes of light as radiation passes through the eyeball.

(th)

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#10 2018-10-06 15:13:12

kbd512
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Registered: 2015-01-02
Posts: 3,184

Re: Ion Neutralization Propulsion

Josh,

The "giant fuel tank" problem of achieving orbit can be solved by using a combination of technologies.  There's no single technology presently available that doesn't require quite a bit of development work.  As you already noted, nuclear is impractical.  Kirk Sorensen already graphically illustrated why over at Selenian Boondocks in a post entitled "SSTO is a bad idea, but NTR SSTO is worse".  Similarly, storing high energy plasma is problematic.  That's why we don't do much of it outside of high energy physics experiments.

Even so, you might find the linked papers of interest:

Plasma Assisted Combustion

Plasma Assisted Combustion by Yinguang Ju - Princeton University

The only near-term practical solution I can think of is an EMALS system a few kilometers in length that's built on the side of the Rocky Mountains.  If we did that, then a LOX/LH2 SSTO with a small but useful payload becomes practical without hundreds of tons of fuel.  If we combined that with a high-power Microwave array, then NTR-like Isp without nuclear technology would be possible and the only propellant aboard the rocket is LH2.  At that point, our payload mass fraction looks a lot like what a jetliner can achieve.  That's a reasonable trade in technology development costs for substantially more efficient rockets.

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#11 2018-10-06 18:47:43

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,805

Re: Ion Neutralization Propulsion

https://www.grc.nasa.gov/WWW/ion/overview/overview.htm

Plasma is an electrically neutral gas in which all positive and negative charges—from neutral atoms, negatively charged electrons, and positively charged ions—add up to zero. Plasma exists everywhere in nature; it is designated as the fourth state of matter (the others are solid, liquid, and gas).

http://www.space-propulsion.com/spacecr … index.html

The radio frequency Ion thruster uses a high-frequency electromagnetic field to ionize xenon gas atoms to form a plasma containing free 'light' electrons and 'heavy' positive ions. The heavy positive ions are then accelerated by an electrostatic field before being ejected to cause thrust.

images of heavy positive and negative ion gas propulsion

As meantioned Positive and negative ions are formed by gaining or losing electrons from neutral atoms. Metallic elements produce positively charged ions by losing electrons while nonmetallic elements produce negatively charged ions by gaining electrons.

List of Positive & Negative Ions

ions-list.png

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#12 2018-10-06 19:24:49

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,846

Re: Ion Neutralization Propulsion

Speaking only for myself, I appreciate the contributions to this discussion by kbd512 and SpaceNut ... I had to give up on my ambitions for a career in physics, but I retain a layman's interest in the field.  I'd like to inquire if a version of a Bose-Einstein condensate might permit iron ions (as just one example) to be stored for use in Josh's (hypothetical) high energy thrust device.  In that case, ions would be created through high energy processes, and then cooled until they can be packed to the density needed for a flight.  This process would take a long time (no doubt) but if the compact storage can hold the accumulation of positive ions, then it wouldn't matter how long the accumulation took. 
(th)

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#13 2018-10-07 04:49:42

elderflower
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Registered: 2016-06-19
Posts: 1,159

Re: Ion Neutralization Propulsion

Doesn't a Bose Einstein condensate behave as a single entity? What would happen if you were to try to subdivide it? Could it exist with a huge electric charge?

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#14 2018-10-08 10:19:40

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,805

Re: Ion Neutralization Propulsion

Metals are a poor choice as it would loss the effective energy from creating the plasma from it once cooled so gasses are best for what is intended for use.

I do agree with tahanson43206 post elsewhere that this should be turned into a thesis abstract document for further project developement....

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#15 2018-10-29 16:58:49

Quaoar
Member
Registered: 2013-12-13
Posts: 425

Re: Ion Neutralization Propulsion

Brian Palaszweski has investigated the possibility to freeze 15% weight of single H hydrogen atoms in hydrogen slush, making a very high energy density propellant.

https://ntrs.nasa.gov/archive/nasa/casi … 009862.pdf

https://ntrs.nasa.gov/archive/nasa/casi … 011425.pdf

Using the NASA rocket simulator, I tried this mixture and found an an exhaust velocity more than 7500 m/s with an expansion ratio of 500 and a chamber temperature of 2900°K

https://cearun.grc.nasa.gov/OFILES/quao6492.html

adding oxygen at an O/F ratio of 1.5, the exhaust velocity is lowered to about 6700 m/s, but thrust is increased: we can add it in the nozzle as an afterburner like in the LANTR.

Hypothetically, if we succeed in storing 30% weight of single H in hydrogen slush, we can reach exhaust velocity of about 9800 m/s like an advanced solid core nuclear rocket, but with chemical rocket like T/W ratio

Last edited by Quaoar (2018-10-30 01:39:12)

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#16 2018-10-31 07:40:47

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,846

Re: Ion Neutralization Propulsion

2018/10/31 Notes for JESS Post

Topic: JESS JoshNH4H Energy Storage System

Thread: Ion Neutralization Propulsion

Focus of this message: Energy storage

While the thread is about propulsion, a subtopic is energy storage.

Summary:

JESS is a category of supercapacitor.  Unlike other supercapacitors, which function through movement of electrons from one plate to another, JESS functions through external removal of electrons from source atoms, and storage of positively charged ions.

JESS delivers electrical power in the same manner as traditional supercapacitors, by facilitating the flow of electrons until electrical balance is achieved.

References:

Post #1 2018-09-28 21:13:48 >> Introduction of positive ion energy storage

Post #2 2018-09-29 03:24:12 >> Confirmation of capacitor application of idea

Post #10 2018-10-06 15:13:12 >> “storing high energy plasma is problematic”

Post #11 2018-10-06 18:47:43 >> “Plasma is an electrically neutral gas”

Other posts in this thread seem to be about propulsion, which is the thread topic.

Discussion:

Given the high potential energy storage capacity of iron:
Per Post #1:

Begin Quotation:
I do know that it has substantial promise: Iron, if stripped of all its electrons, would be able to store 619 eV/amu, which works out to almost 60 GJ/kg.
End Quotation.

Consider a spherical supercapacitor:
Outer surface is metal at ambient temperature and electrical potential

Inner surface is metal at ambient temperature and electrical potential

Between Outer and Inner surfaces there is a dielectric

However, in the case of JESS, the capacitance of the system is NOT an objective.

The concept here is to “treat” iron atoms in a separate system, so they have no electrons, but are NOT moving rapidly.  In fact, the colder the ions are at the time of injection, the better, because thermal activity is not desirable for this system.

Inject these iron ions into the interior space of the sphere, and do not permit escape.

Gravity will pull the ions toward the center of the Earth (assuming application on the Earth).

Electrons will move from the interior wall to the ions until the interior wall is ionized.

Neutralized ions will fall to the bottom of the sphere.

As ions are added, the ability of the interior wall to yield electrons will decrease.

Meanwhile, electrical potential will build between inner and outer walls through the dielectric.

To be determined:

1)How many ions can be added before the dielectric breaks down
2)Is jostling of ions inside the sphere a potential source of heat to be bled off
3)Is the injection nozzle a fatal point of weakness
4)How can energy be obtained from this system in a controlled way?

When iron ions are supplied with electrons from the outside pathway, they will fall to the bottom of the sphere if they are not already there.

These iron atoms can then be removed via the injection pathway and returned to the external ionization system.

Per Post #13 2018-10-07 04:49:42  >> Bose Einstein condensate

I agree that the conditions described do not favor a Bose Einstein condensate.

(th)

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