VASIMR - Solar Powered?

Antius · 2017-04-07 13:14:17

How about butane? At -1C its vapour pressure is 1bar.

Do you not need to pressurise tanks anyway to prevent cavitation at turbopump inlet? Propane has a vapour pressure of about 9bar at room temp, so would seem to be the ideal hydrocarbon.

Oldfart1939 · 2017-04-07 13:58:43

The density of these fuels is a disadvantage. The Isp is OK in both cases, but the Id is low. Need bigger (and thus, heavier) tankage for a given amount of Enthalpy.

Antius · 2017-04-07 14:29:59

Styrene perhaps?

http://www.engineeringtoolbox.com/liqui … d_743.html

https://en.m.wikipedia.org/wiki/Styrene

Density = 903kg/m3 even better than kerosene (820kg/m3). Only problem with an alkene is that small amounts of oxygen can serve as free radical catalysts for polymerization. A problem with ethylene that has caused accidents. Not so sure how big a problem this would be with styrene.

The reason I chose methane was that there already exists a space rated engine in the right thrust range for the 100te lander. But in hindsight, a reusable engine for a lunar lander would probably need to be pressure-fed anyway. Otherwise, you need a fresh turbopump for every new landing. It would however be quite an experience carrying out the EVA needed to change it 60 miles above the surface of the moon.

Last edited by Antius (2017-04-07 14:41:24)

Oldfart1939 · 2017-04-07 15:03:21

Styrene? NOOOOOO! This could readily thermally polymerize in the cooling lines! This stuff is the WORST possible choice. Also, as an aromatic hydrocarbon, is very prone to coking. Oxygen is actually a polymerization inhibitor. The final 15 years of my professional career were spent synthesizing various substituted styrenes.

SpaceNut · 2017-04-07 19:40:47

Here are some slides which have the thruster stuff and
http://images.spaceref.com/fiso/2015/05 … -20-15.pdf

http://spirit.as.utexas.edu/~fiso/telec … -13-13.pdf
http://spirit.as.utexas.edu/~fiso/telec … -29-15.pdf

Original links from the site were moved but I did find them once again based on this next key
For 2007-2009 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist07-09.htm
For 2010-2012 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist10-12.htm
For 2013-2015 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist13-15.htm

Terraformer · 2017-04-08 03:35:03

For powering an electric thruster, how about leaving the solar system behind and using microwave beams to get the power to the ship?

Antius · 2017-04-08 03:40:21

SpaceNut wrote:

Here are some slides which have the thruster stuff and
http://images.spaceref.com/fiso/2015/05 … -20-15.pdf
http://spirit.as.utexas.edu/~fiso/telec … -13-13.pdf
http://spirit.as.utexas.edu/~fiso/telec … -29-15.pdf
Original links from the site were moved but I did find them once again based on this next key
For 2007-2009 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist07-09.htm
For 2010-2012 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist10-12.htm
For 2013-2015 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist13-15.htm

Thanks Spacenut. I will give these a read. The second of the PDFs gives delta-V to lunar orbit and back as 8km/s with impulsive thrust. This suggests that delta-v from LEO to lunar surface is 6km/s. If lunar oxygen is available at a base on the lunar surface, it should therefore be possible to build a methane-oxygen fuelled crew cycler that would complete a journey from LEO to lunar surface and back refuelling only with methane in LEO. As LOX is about 80% of propellant mass, refilling with LOX on the lunar surface prevents the mass ratio from becoming ridiculous. The same type of vehicle could be used to ferry cargo between LLO and the lunar surface, taking on payload and methane from the SEP tug in LLO. These vehicles would spend their entire lives cycling between lunar surface and LLO.

Lunar colonisation would be possible by mass-producing three classes of vehicles. (1) An Earth-launched vehicle who's function is to transport crew and material to LEO; (2) An SEP tug, conveying cargo from LEO to LLO and back; (3) A methane-oxygen reusable vehicle that will be specialised to (a) Convey human beings between LEO and lunar surface and (b) Carry cargo between LLO and lunar surface. It would be best to use separate vehicles for a and b, although the same basic design of vehicle could be used.

In the short-term, methane and argon would need to be supplied from Earth. If lunar materials can be used to manufacture SEP and chemical propellants, the effective payload fraction delivered to the lunar surface would at least double. This could be done for example, if it became possible to electromagnetically launch bulk materials from the moon. This would then serve as propellant for the SEP tug and silicon could be converted into silane using lunar regolith based hydrogen.

If we develop that capability, manufacturing other items in Earth orbit using lunar materials would be a natural extension. For orbital altitudes above 1000km, circular orbits have a lifetime of millennia, even if not actively maintained.
http://www.spaceacademy.net.au/watch/debris/orblife.htm

Last edited by Antius (2017-04-08 03:50:22)

tahanson43206 · 2020-11-08 20:55:42

It's been a while since anyone posted about VASIMR

Here is part of an article July, 2017, just after Antius posted last in this topic ...

https://www.spaceflightinsider.com/conf … s-39-days/

In Arthur C. Clarke’s classic science fiction novels and movies 2001: A Space Odyssey and 2010: Odyssey Two, the spaceships Discovery and Alexei Leonov make interplanetary journeys using plasma drives. Nuclear reactors heat hydrogen or ammonia to a plasma state that’s energetic enough to provide thrust.
In 1983, seven-time Space Shuttle Astronaut Franklin Chang Diaz turned Clarke’s speculations into reality with an engine known as the Variable Specific Impulse Magnetoplasma Rocket (VASIMR).
An electric power source ionizes hydrogen, deuterium, or helium fuel into a plasma by stripping away electrons. Magnetic fields then direct the charged gas in the proper direction to provide thrust.
“A rocket engine is a canister holding high-pressure gas,” Chang Diaz explained. “When you open a hole at one end, the gas squirts out and the rocket goes the other way. The hotter the stuff in the canister, the higher the speed it escapes and the faster the rocket goes. But if it’s too hot, it melts the canister.”
The VASIMR engine is different, Chang Diaz explained, because of the fuel’s electrical charge: “When gas gets above 10,000 [kelvins], it changes to plasma – an electrically charged soup of particles. And these particles can be held together by a magnetic field. The magnetic field becomes the canister, and there is no limit to how hot you can make the plasma.”

The article includes graphics showing the operation of the design (Note Chang Diaz).

Edit#1: Here is a link to an article by Dr. Zubrin casting buckets of ice water on the VASIMR concept.
https://spacenews.com/vasimr-hoax/

The VASIMR Hoax
by Robert Zubrin — July 13, 2011

In looking for current status of VASIMR, the most recent article I could find was from 2018 ...

https://www.fromspacewithlove.com/vasimr/

– News of August 15, 2017 –
Ad Astro Rocket has just passed the second stage of a contract with NASA. Indeed, in 2015 NASA has invested $ 10 million for Ad Astra Rocket so that the company carries out extensive testing of its VASIMR engine. The objective is to carry out in 2018 a test of continuous operation of the VASIMR plasma engine with a power of 100 kilowatts.
One of the major challenges ahead is VASIMR’s power supply. In its current design, the engine is designed to operate optimally at a power of 200 kilowatts. But even the huge solar panels of the international space station can not provide a power greater than 120 kilowatts. A nuclear reactor identical to those of the aircraft carriers would be sufficient. Like many means of propulsion, VASIMR is limited by the unavailability of such sources of energy.
Image by NASA; Posted in Public domain, via Wikimedia Commons
By From Space With Love

One of the ** really ** large buckets of ice water tossed by Dr. Zubrin was the size of the nuclear power plant. The quote above appears to concede the point. I liked the reference to a nuclear power plant from an aircraft carrier.

I asked Google about that, and received this:

A1B reactor - Wikipediaen.wikipedia.org › wiki › A1B_reactor
Using A4W data with a 25% increase in thermal power, the A1B reactors likely produce enough steam to generate 125 megawatts (168,000 hp) of electricity, plus 350,000 shaft horsepower (260 MW) to power the four propeller shafts.
People also ask

I would imagine a VASIMR could produce decent thrust with a reactor producing 125 MW of electric power. However, the mass of the reactor and shielding would (presumably) take up a large part of the thrust.

(th)

tahanson43206 · 2021-08-05 18:16:52

Almost exactly one year ago, I posted a reminder to the VASIMR topic ...

I've had a year to think about the problem of supplying power to VASIMR.

During that year numerous members of the NewMars forum have provided inspiration by talking about entirely unrelated topics, but here an there I picked up hints of ideas that might help to address the VASIMR power problem.

In particular, Quaoar led the forum in an exploration of the physics of driving an intergalactic exploration probe using power developed at Mercury.

It came to me then that it is not necessary to wait until we are ready to send an intergalactic probe to use the basic idea.

A ship travelling to Mars is as good a target for focused energy as any that might be proposed.

The posts above quote power levels in the 100-200 kilowatt range ....

I see no reason at all why a power transmitter based on the Moon could not deliver power to a vessel headed away from Earth, whether inbound to Venus or outbound to Mars or the outer system.

Likewise, I see no reason at all why Phobos could not provide a similar service for vessels inbound to Mars or heading out for other destinations.

I'd like to invite members with posting privileges to consider the math involved.

Questions to be addressed include what kind of receiving array is most effective for the space craft over Earth-Mars distances, and what kind of equipment on the Moon is needed to deliver power reliably to a vessel in transit for weeks or months if necessary.

The Sun can be counted upon to provide energy for the venture, and the Moon can be counted upon to hold steady in its course.

It's up to humans to work out the details of how this could and would be done.

(th)

SpaceNut · 2021-08-05 18:44:42

The electromagnetic spectrum diffuses with distance and would require refocusing the beam of energy with distance such as to keep power levels as close as possible to the starting point. With each recombining of the beam there will be losses.

tahanson43206 · 2021-08-05 19:02:49

For SpaceNut re #110

Thank you for your important reminder!

Can you (would you if you have time) find precise numbers for diffusion of laser beams as compared to focused beams?

My understanding is that parabolic mirrors are able to achieve focus on a single star light years away.

Presumably a light transmitted from such a mirror to the distant star would arrive at the star as a single point of light.

I understand that laser beams ** do ** spread, but (apparently) the spread is less than is true for an ordinary beam of light.

A single photon does NOT spread (as I understand the situation). If an operator is wanting to send a supply of photons to a remote vessel, I would imagine the operator would want to arrange things so that each photon transmitted arrives at the target without having taken a side trip to somewhere else.

Your point in Post #110 is an excellent starting point for what I hope will be a productive discussion that might lead to a solid recommendation for the developers of the VASIMR engine.

(th)

SpaceNut · 2021-08-06 18:52:37

Lasers are collimated light using lenses to shape the beam for distance of projection and it will spread out once more with enough distance. I am sure that one can google for function but its about the numbers for the beam focus that matter not just power.
If one could supply the solar array with the beam over distance its still going to be the efficiency of the panels to storage rate that will be the issue for making use of the stored energy for the VASIMR engine.

tahanson43206 · 2021-08-06 19:46:56

For SpaceNut re #112

Thanks for keeping this concept for VASIMR going for at least one more round ....

It sounds as though you are ready to accept that photons can be delivered to distant targets with appropriate technical adjustments.

Regarding efficiency .... The recent post in another topic about use of nanometer scale antenna and rectifier systems offers hope that efficiency of a receiving antenna at a VASIMR vessel can approach or exceed 50%. Even the 50% that is NOT captured by the antenna need not be lost, but instead can be collected by suitable heat sensitive material. With the deep space cold on the back side, such panels should be able to achieve at least 20% thermal efficiency in generating electricity.

Todo: Find thermal efficiency of Seebeck effect with 100 Centigrade on front and 0 Kelvin on the other.

(th)

tahanson43206 · 2022-01-26 12:39:22

The recently revisited post of C M Edwards, about using chemically stored energy to power a plasma engine, inspired me to ask Wikipedia for an update on the subject.

The Wikipedia article was last updated: This page was last edited on 17 January 2022, at 22:49 (UTC).

Based on that update date, I conclude not much has changed from the previous status.

The system is (apparently) less efficient than an ion engine, and it (apparently) requires much more mass to operate.

On top of that it (apparently) requires superconducting magnets that themselves are energy hungry (assuming they require cooling).

That is a detail that may be discussed in the Wiki. I scanned the article, so may have missed it.

In any case, as nearly as I can tell, VASIMR is no closer to practical use than it was 10 years ago, and that was essentially Zilch.

This topic is entitled VASIMR - Solar Powered ....

The topic accumulated 4 pages before it entered hibernation. Perhaps someone in all those posts found a way to collect solar power in a way that did not add massive structures to the space vessel, and corresponding great mass, which would further weaken the limited effect of the engine.

(th)

tahanson43206 · 2023-12-25 14:31:05

It may be time to take another look at VASIMR...

Per Google:

One of the biggest concerns for the VASIMR project in general is that, to be able to travel to Mars in a short amount of time, it needs a nuclear power system that is capable of delivering 200 kW to the engine.
Plasma, Ion-Thrusters, and VASIMR
University of Colorado Boulder
https://www.colorado.edu › kantha › content › pla...
PDF
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200 Kw seems modest compared to the 1 megawatt target of the shipping container power pod under discussion in other topics.

Update later: In looking back over the topic, I see that various sizes have been proposed for VASIMR, and 200 Kw appears to be at the low end.

(th)

tahanson43206 · 2025-03-22 19:06:22

Today is 2025/03/22 ... a full year since our last post in this topic.

I am intrigued by the title of the topic, because I arrived here to drop off a conversation with Google's Gemini about VASIMR.

The conversation opens with some general background on electrostatic ion drives, and concludes with VASIMR.

The reason I am intrigued by the topic title is that we have a robust investigation of solar powered propulsion going on, thanks to work of kbd512 in the latter part of 2024 and early 2025.

Update: I went back and read the first full page of posts... that was a solid series of posts! It is possible the high quality continued on but I do not have time right now to confirm that guess. What I ** did ** confirm is that most contributors seemed to have reasonably good understanding of the VASIMR system as it was described at that time.

Conversation with Gemini
Hi Gemini! Thanks for all the help you have provided with previous questions. I hope this one will prove interesting for you as well as for me. I am thinking about a specific kind of space drive that uses ions to create thrust. The amount of thrust created in tiny, and I'm curious about the reasons. i am confident engineers are getting the maximum performance they can out of the systems they create, but my question here is why the performance is so poor. I'm looking for the "root cause" if that is available.
Hello! I'm glad to help you explore the fascinating world of ion drives. You're right, while incredibly efficient in terms of propellant usage, ion drives produce very low thrust. Let's delve into the root causes of this limitation.
Here's a breakdown of the key factors:
1. The Fundamental Physics of Thrust:
Newton's Second Law: Thrust is essentially a reaction force. To accelerate a spacecraft, we need to eject mass at a certain velocity. This is expressed as:
F=m˙v
Where:
F is the thrust (force).
m˙ is the mass flow rate (mass ejected per second).
v is the exhaust velocity (velocity of the ejected mass).
Ion drives prioritize high exhaust velocity (v): They accelerate ions to extremely high speeds using electric fields. This is their strength.
The limitation is the mass flow rate (m˙): Ion drives eject very small amounts of mass per second. This is their weakness.
2. Why the Low Mass Flow Rate?
Space Charge Limitations:
Ions, being charged particles, repel each other. As you try to increase the number of ions in a given volume, the electrostatic repulsion becomes significant. This "space charge effect" limits the density of the ion beam, and thus the mass flow rate.
It is difficult to generate and accelerate a very dense beam of ions without the beam spreading out, or the ions repelling so much that the system becomes inefficient.
Power Constraints:
Generating and accelerating ions requires significant electrical power. While ion drives are efficient in their use of propellant, they are not necessarily efficient in their use of electrical power.
Increasing the mass flow rate requires proportionally more power. Current space-based power systems, primarily solar panels or nuclear reactors, have limitations on the amount of power they can provide.
Increasing the power of the ion drive, increases the mass of the power supply. This increase in mass counteracts the benefits of the increased thrust.
Neutralization Requirements:
The ejected ion beam is positively charged. To prevent the spacecraft from accumulating a negative charge (which would attract the ions back and reduce thrust), a neutralizer is used. This typically involves ejecting electrons to balance the charge.
The need to neutralize the beam, adds to the complexity of the system, and can add to the limitations of the mass flow rate.
Engineering Constraints:
Creating systems that can handle the extreme environments of space, along with the high voltages and ion densities needed is very difficult.
The long life requirements of space missions, also add to the complexity of the engineering.
Root Cause Summary:
The root cause of the low thrust in ion drives boils down to a fundamental trade-off between exhaust velocity and mass flow rate. While ion drives excel at achieving high exhaust velocities, they are inherently limited in the amount of mass they can eject per second due to space charge effects and power limitations.
In essence:
It's easier to accelerate a small number of ions to very high speeds than it is to accelerate a large number of ions to the same speed.
The amount of electrical power available in space is a significant limiting factor.
I hope this explanation helps!
Thank you for the opening reply, which certainly appears to cover the essentials. If you are willing, let's try to dig a bit deeper. I appreciate your opening with the fact that positively charged ions are going to repel each other. However, positively charged ions are kept in tight boundaries in fusion devices such as Tokamaks or Stellarators. As you "think" about the difference, please analyze the differences that may allow one to succeed while the other appears to fail?
You've hit upon a very insightful comparison! It's true that fusion devices like tokamaks and stellarators confine positively charged ions (plasma) quite effectively, despite the inherent repulsion. Let's analyze the differences that allow fusion devices to achieve this, and why those solutions don't directly translate to high-thrust ion drives:
1. Magnetic Confinement vs. Electrostatic Acceleration:
Fusion Devices (Tokamaks, Stellarators):
These devices rely on magnetic confinement. Powerful magnetic fields are used to constrain the hot, ionized plasma. The charged particles follow helical paths along the magnetic field lines, preventing them from escaping.
The magnetic fields exert a force perpendicular to the velocity of the charged particles, causing them to move in curved paths.
Ion Drives:
Ion drives use electrostatic acceleration. Electric fields are used to accelerate the ions in a specific direction to create thrust.
The electric fields exert a force parallel to the field lines, accelerating the particles linearly.
The goal of the ion drive is to get the ions to leave the device, not to contain them.
2. Density and Temperature Differences:
Fusion Devices:
Fusion plasmas are extremely hot (millions of degrees Celsius) and relatively dense.
The high temperature means the ions have very high kinetic energy, and the magnetic fields need to be incredibly strong to contain them.
Fusion devices are designed to maintain these high densities for long periods of time, so that fusion can occur.
Ion Drives:
Ion drives operate with much lower ion densities and temperatures.
The goal is to create a well-collimated beam of ions with a high velocity, not to achieve nuclear fusion.
The ions are accelerated, and then ejected.
The density of ions in a fusion reactor is still vastly larger than the density of ions in an ion thruster.
3. Scale and Geometry:
Fusion Devices:
Fusion devices are typically large and complex, with massive superconducting magnets.
The geometry is designed to create a closed magnetic field configuration that confines the plasma.
Ion Drives:
Ion drives are designed to be compact and lightweight, suitable for spacecraft.
The geometry is optimized for creating a directed beam of ions.
The area that the ions are accelerated through in an ion drive is very small compared to the volume of a fusion reactor.
4. Neutrality:
Fusion Devices:
Fusion plasmas are quasi-neutral, meaning they contain roughly equal numbers of positive ions and negative electrons. This helps to reduce the overall electrostatic repulsion.
Ion Drives:
Ion drives start with a positively charged ion beam. Neutralization occurs after the beam has exited the thruster. The beam inside the thruster is not neutral.
Why Fusion Confinement Doesn't Translate to Ion Drives:
The magnetic confinement techniques used in fusion are not practical for creating a high-thrust ion drive. The magnetic fields would add significant mass and complexity to the spacecraft.
The geometry of a fusion device is not conducive to creating a directed beam of ions.
The goal of high density for long periods of time, is opposite of the goal of ion drives, which is to eject ions as quickly as possible.
The large amount of power required for magnetic confinement is not available for use in ion drives.
In essence:
While both fusion devices and ion drives deal with positively charged ions, their goals, operating parameters, and engineering constraints are vastly different. Fusion devices prioritize confinement for energy production, while ion drives prioritize acceleration for propulsion. These differing priorities lead to fundamentally different design choices.
Thank you for the helpful comparison. I did not realize that existing ion drives use electrostatic propulsion rather than magnetic. Please double check your references. I'd like to be sure the information you have provided covers all existing ion drives.
You are absolutely right to ask for clarification, and I appreciate you pointing out the potential for ambiguity in my previous response. I need to be more precise about the terminology.
You are correct: Almost all currently operational and planned ion drives use electrostatic acceleration, not magnetic acceleration, to create thrust.
Here's a more accurate breakdown:
Electrostatic Ion Thrusters:
These are the most common type of ion thruster.
They use electric fields to accelerate ions.
Examples include gridded ion thrusters and Hall-effect thrusters.
These are the systems I was describing in my previous response.
Magnetic Plasma Thrusters (MPTs):
These thrusters do use magnetic fields to accelerate plasma.
They are less common than electrostatic ion thrusters.
They can, in theory, achieve higher thrust levels than electrostatic thrusters, but they also have their own set of challenges, including:
Lower exhaust velocities compared to electrostatic ion thrusters.
Higher power requirements.
Greater complexity.
Variable Specific Impulse Magnetoplasma Rocket (VASIMR) thrusters are a type of magnetic plasma thruster.
MPTs are still in development, and are not as prevalent as electrostatic ion thrusters.
Key Clarification:
When I discussed the limitations of "ion drives" in my previous responses, I was primarily referring to electrostatic ion thrusters, which are the dominant type.
The vast majority of operational ion drives use electrostatic methods.
While magnetic plasma thrusters do exist and use magnetic fields, they are not as widely used, and have their own set of limitations.
I apologize for the lack of precision in my previous answers. I am still under development, and your questions are helping me to improve. Thank you for helping me to be more accurate.
Thank you for your helpful reminder of the VASIMR system. That system would appear to be more applicable to our present investigation. Can you discover how the VASIMR system prepares ions for acceleration? Is there a requirement for a particular kind of atom for this application?
You're asking about some very specific and interesting aspects of the VASIMR system. Here's a breakdown of how it prepares ions for acceleration and the propellants it uses:
Ion Preparation in VASIMR:
The VASIMR system employs a multi-stage process to prepare ions for acceleration:
1. Ionization (Helicon Stage):
The process begins with the injection of a propellant gas into a chamber.
Radio frequency (RF) waves, generated by a helicon antenna, are used to ionize the gas, creating a plasma. This means the RF energy strips electrons from the propellant atoms, resulting in a mixture of ions and electrons.
This initial plasma is relatively "cold" compared to the later stages.
2. Heating (Ion Cyclotron Resonance - ICR):
The plasma then moves into a second chamber where it's further heated using ion cyclotron resonance (ICR).
Again, RF waves are used, but this time they're tuned to the cyclotron frequency of the ions. This causes the ions to absorb the RF energy and their kinetic energy to increase dramatically, resulting in a very hot plasma.
This heating stage is crucial for achieving the high exhaust velocities that VASIMR is designed for.
3. Magnetic Nozzle Acceleration:
The super heated plasma is then directed through a magnetic nozzle.
The diverging magnetic field of the nozzle converts the thermal energy of the plasma into directed kinetic energy, accelerating the ions out of the thruster.
Propellant Requirements:
VASIMR is designed to use various propellants, but some are more efficient than others.
Hydrogen: Is considered a very desirable propellant, due to its low molecular weight, which allows for very high exhaust velocities.
Argon: Has also been used in testing, and is another possible propellant.
It is worth noting that the VASIMR system is designed to be able to use a greater variety of propellants than standard ion thrusters.
The ability to utilize various propellants, gives the VASIMR system a great deal of flexibility.
Key Considerations:
The use of RF heating and magnetic fields allows VASIMR to achieve very high exhaust velocities, which translates to high specific impulse (efficient propellant use).
The system's ability to vary the amount of RF power applied to the ionization and heating stages allows for variable specific impulse, meaning the thruster can be optimized for different mission phases.
I hope this detailed explanation is helpful.
Thank you very much for the information you have collected, and for the careful and helpful organization of the text. While I am away, best wishes for similar success as you attempt to help your other customers.
You're very welcome! I'm glad I could provide helpful information. I appreciate your kind words and wish you all the best as well. If you have any more questions in the future, don't hesitate to ask. Have a great day!

(th)

tahanson43206 · 2025-03-28 11:58:19

This post is a follow up to #116. I asked ChatGPT4o to take a closer look at how ions are created in the VASIMR system, and how they are accelerated using magnetic fields. We included discussion of how electrons are supplied at the stern of the vessel to neutralize the positively charged ions.

VASIMR Ion Generation and Magnetic Accelerator - Summary
Plasma Generation & Ionization Process
Plasma Generation: Uses radiofrequency (RF) heating to ionize a propellant such as hydrogen or argon.
Ionization Process: RF waves energize electrons, causing collisions with neutral atoms, resulting in ionization.
Helicon Antenna: Generates dense, cool plasma through helicon wave propagation.
Ion Cyclotron Heating (ICH): Plasma is further heated via ion cyclotron resonance heating (ICRH) to increase ion velocity.
Magnetic Accelerator Design (Magnetic Nozzle)
Magnetic Confinement: Superconducting magnets confine and guide plasma through the rocket's core.
Magnetic Nozzle: Converts thermal energy of plasma into directed kinetic energy, enhancing thrust.
Acceleration Process: Magnetic field shaping directs plasma to achieve high specific impulse (ISP).
Electron Neutralization
Issue of Charge Imbalance: Without neutralization, the spacecraft would accumulate negative charge, attracting expelled ions.
Neutralizer System: Releases electrons to recombine with the ionized exhaust stream.
Plasma Bridge / Hollow Cathode: Options include a hollow cathode or a plasma bridge to generate electrons for neutralization.
This summary provides a foundation for further exploration of the VASIMR design, particularly the magnetic nozzle and electron neutralization systems.

Looking ahead: I plan to ask ChatGPT4o if there is any chance the acceleration of ions in the VASIMR system can be precisely controlled. There exists an application for very precisely controlled protons, and I'm curious to know if the system designed by Franklin Chang Diaz and associates has that capability.

Wikipedia
https://en.wikipedia.org › wiki › Variable_Specific_Imp...
The VASIMR concept originated in 1977 with former NASA astronaut Franklin Chang Díaz, who has been developing the technology ever since.

1977 to 2025 >> 23+25 >> 48 years ... Good Grief!

chang-diaz bio current
NASA (.gov)
https://www.nasa.gov › chang-diaz_franklin_0
PDF
FRANKLIN R. CHANG-DÍAZ (PH.D.) NASA ASTRONAUT (FORMER). PERSONAL DATA: Born April 5, 1950, in San José, Costa Rica, to the late Mr. Ramón. A. Chang-Morales and ...
2 pages

1950-2025>> 75 still young by modern standards.

(th)

tahanson43206 · 2025-03-28 15:27:29

I asked Google's Gemini for possible references to VASIMR.

Conversation with Gemini
Hi Gemini! Thank you for your help with many previous questions and inquiries! Today I'm hoping you can find any information that might be available about the VASIMR spacecraft propulsion system invented by Dr. Franklin R. Chang-Diaz. He and his team have been working on this since 1977 (I'm told) but I could find no books on the subject at Amazon. Can you find anything?
It's true that Dr. Franklin R. Chang-Diaz's VASIMR (Variable Specific Impulse Magnetoplasma Rocket) project is a fascinating area of space propulsion technology. Here's a breakdown of what I found:
VASIMR Basics:
VASIMR is an electrically powered propulsion system that uses plasma to generate thrust.
It offers the potential for higher efficiency and faster travel times compared to traditional chemical rockets.
The engine works by ionizing a gas (like argon) and heating it to create plasma, which is then accelerated by magnetic fields.
A key advantage is the ability to vary the specific impulse (Isp), allowing for flexible mission profiles.
Key Points:
The technology has been in development for many years, with Dr. Chang-Diaz and his company, Ad Astra Rocket Company, leading the effort.
VASIMR aims to bridge the gap between high-thrust chemical rockets and high-efficiency electric propulsion systems.
It has potential applications for various space missions, including:
Faster trips to Mars.
Cislunar logistics.
Deep-space exploration.
Where to find Information:
Ad Astra Rocket Company: The company's website (adastrarocket.com) is a primary source of information on VASIMR.
Wikipedia: The Wikipedia page on "Variable Specific Impulse Magnetoplasma Rocket" provides a good overview of the technology.
YouTube: There are many informative videos on YouTube, including interviews with Dr. Chang-Diaz, that explain how VASIMR works.
Scientific papers and journals, are also good sources of information.
Challenges:
Developing a high-power, low-mass power source is a significant challenge.
Thermal management is also a critical consideration.
While finding dedicated books solely on VASIMR might be difficult, the information available online through reputable sources provides a comprehensive understanding of this cutting-edge technology.
Collisional Losses in a VASIMR (Variable Specific-Impulse Magnetoplasma Rocket)
Source icon
digitalcommons.usu.edu
Recent Progress on the VASIMR Engine - NASA Technical Reports Server (NTRS)
Source icon
ntrs.nasa.gov
Variable Specific Impulse Magnetoplasma Rocket - Wikipedia
Source icon
en.wikipedia.org
Improved Thermo-Mechanical Design of the VASIMR RF Coupler - NASA TechPort - Project
Source icon
techport.nasa.gov
VASIMR Rocket explained by Franklin Chang-Diaz - YouTube
Source icon
www.youtube.com
Thank you! Your assistance is once again most helpful!
You're very welcome! I'm glad I could provide some helpful information about the VASIMR project. If you have any more questions about space propulsion, or any other topic, feel free to ask!

(th)

RGClark · 2025-03-28 16:18:13

Several thin-film solar cell research efforts have come up with better than 1kW/kg power density solar cells, the power density needed for VASIMR. The highest one I’ve seen is this:

Solar-cell-packin' drone uses sunlight for on-the-spot recharging
By Ben Coxworth
April 19, 2024
Created by scientists at Austria's Johannes Kepler University Linz, the lightweight, flexible cells are made of a semiconductor material known as perovskite, and they're less than 2.5 micrometers thick – that's just 1/20th the width of a human hair. And importantly, they're 20.1% efficient at converting sunlight into electricity, plus they boast a power output of up to 44 watts per gram.
In a proof-of-concept test of the technology, the scientists mounted a ring-shaped array of 24 of the cells on a commercially available CX10 miniature quadcopter, which was dubbed the Solar Hopper. The array made up just 1/25th of the augmented aircraft's total weight, with the cells themselves making up only 1/400th.
https://newatlas.com/drones/solar-cells … -sunlight/

It is notable though that last sentence in this passage suggests the structural elements make up the greatest component of the weight. Still, being out of the Earth’s gravity and at very low acceleration for our application, the structural elements would be much reduced.

Bob Clark

Last edited by RGClark (2025-03-28 16:31:30)

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#101 2017-04-07 13:14:17

Re: VASIMR - Solar Powered?

#102 2017-04-07 13:58:43

Re: VASIMR - Solar Powered?

#103 2017-04-07 14:29:59

Re: VASIMR - Solar Powered?

#104 2017-04-07 15:03:21

Re: VASIMR - Solar Powered?

#105 2017-04-07 19:40:47

Re: VASIMR - Solar Powered?

#106 2017-04-08 03:35:03

Re: VASIMR - Solar Powered?

#107 2017-04-08 03:40:21

Re: VASIMR - Solar Powered?

#108 2020-11-08 20:55:42

Re: VASIMR - Solar Powered?

#109 2021-08-05 18:16:52

Re: VASIMR - Solar Powered?

#110 2021-08-05 18:44:42

Re: VASIMR - Solar Powered?

#111 2021-08-05 19:02:49

Re: VASIMR - Solar Powered?

#112 2021-08-06 18:52:37

Re: VASIMR - Solar Powered?

#113 2021-08-06 19:46:56

Re: VASIMR - Solar Powered?

#114 2022-01-26 12:39:22

Re: VASIMR - Solar Powered?

#115 2023-12-25 14:31:05

Re: VASIMR - Solar Powered?

#116 2025-03-22 19:06:22

Re: VASIMR - Solar Powered?

#117 2025-03-28 11:58:19

Re: VASIMR - Solar Powered?

VASIMR Ion Generation and Magnetic Accelerator - Summary

#118 2025-03-28 15:27:29

Re: VASIMR - Solar Powered?

#119 2025-03-28 16:18:13

Re: VASIMR - Solar Powered?

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