Combined photon and particle beam for self-focusing propulsion beam

There has been NASA development of laser (photon) beamed propulsion and particle beam propulsion. Both have scattering and focusing issues at long distances.

They are looking at optimal cooling and other issues.

There is a NIAC study of having particles trapped in photon beam where the interaction could be self-focusing. It could enable a 50 GW beam to propel a 1-kilogram spacecraft to Proxima (270,000 AU – about 4 light years).

Questions related to whether any physical law is violated related to entropy.

If this works it will also improve beamed propulsion for cubesat and in solar system missions.

It would not be usable from Earth, since it would collide with the atmosphere.

75 thoughts on “Combined photon and particle beam for self-focusing propulsion beam”

  1. I don’t know… it kind of sounds like magic to me. Ionized beams just want to diverge. Internal electrostatic charges of neighboring ions — even if their pretty far away, like meters — tends to diverge ionized beams. Neutral beams tend to diverge because of much smaller brownian collision or if you will “gas pressure’ forces. Granted, a gigawatt beam, 5 m² in cross section, isn’t going to have a whole lot of gas pressure. But it’ll have some! Laser beams tend to diverge because of their source-side fundamental divergence. Doesn’t matter (much) how wide or narrow the beam is, the quality of the final mirror which collimates the beam to its final form imparts an irreducible amount of divergence in the beam. But I guess the idea is, by combining the two, the index-of-refraction of a long straight whisp of neutral ions will have — not unlike a communications graded-index fiber-optic cable — a graded index of refraction, which in turn will tend to keep the passing light centered on the beam, not escaping the core … due to “perfect internal reflection” optical phenomena. Got that part! Question is, what force(s) in turn work to keep the ion beam collimated? Hmmm… I suppose the light could very infrequently ionize neutral atoms. The ion-pairs, positive charged nuclei and negative charged electrons would go flying apart, but as I said about electrostatic forces working over meters when given enough time, the ions would “feel the attraction” of their opposite member closeby. And would tend to recombine. And the highest density of ions would therefore be near the center of the neutral beam. The not-so-neutral beam. Thing is, this wouldn’t necessarily tend to confine the neutral part of the beam. Hmmm… have to think about that more. _______ A 50 GW combined energy beam is something pretty special. What’s the split. 50:50? I should go read the detailed article. Not much time left. In any case, 50 GW is a LOT of power to be swinging around in orbit s

  2. Sounds promising. Note that the difference in velocity between the light and the particles would tend to suppress instabilities.

  3. I don’t know… it kind of sounds like magic to me. Ionized beams just want to diverge. Internal electrostatic charges of neighboring ions — even if their pretty far away like meters — tends to diverge ionized beams. Neutral beams tend to diverge because of much smaller brownian collision or if you will gas pressure’ forces. Granted” a gigawatt beam 5 m² in cross section isn’t going to have a whole lot of gas pressure. But it’ll have some!Laser beams tend to diverge because of their source-side fundamental divergence. Doesn’t matter (much) how wide or narrow the beam is the quality of the final mirror which collimates the beam to its final form imparts an irreducible amount of divergence in the beam. But I guess the idea is by combining the two the index-of-refraction of a long straight whisp of neutral ions will have — not unlike a communications graded-index fiber-optic cable — a graded index of refraction which in turn will tend to keep the passing light centered on the beam” not escaping the core … due to “”perfect internal reflection”””” optical phenomena. Got that part!Question is”” what force(s) in turn work to keep the ion beam collimated? Hmmm… I suppose the light could very infrequently ionize neutral atoms. The ion-pairs positive charged nuclei and negative charged electrons would go flying apart but as I said about electrostatic forces working over meters when given enough time”” the ions would “”””feel the attraction”””” of their opposite member closeby. And would tend to recombine. And the highest density of ions would therefore be near the center of the neutral beam. The not-so-neutral beam. Thing is”” this wouldn’t necessarily tend to confine the neutral part of the beam. Hmmm… have to think about that more. _______A 50 GW combined energy beam is something pretty special. What’s the split. 50:50? I should go read the detailed article. Not much time left.In any case 50 GW is a LOT of power to be swing”

  4. Sounds promising. Note that the difference in velocity between the light and the particles would tend to suppress instabilities.

  5. I’m fairly optimistic about neutral mass beams; If you use laser cooling on the beam to reduce the perpendicular component of the temperature, you can get the divergence down to an absurdly low level. Especially if you have stations along the beam refocusing it every 10th of a light year or so. But I really prefer the use of “particles” in the mass beam that are large enough to have their own guidance and propulsion systems.

  6. I’m fairly optimistic about neutral mass beams; If you use laser cooling on the beam to reduce the perpendicular component of the temperature you can get the divergence down to an absurdly low level. Especially if you have stations along the beam refocusing it every 10th of a light year or so.But I really prefer the use of particles”” in the mass beam that are large enough to have their own guidance and propulsion systems.”””

  7. I would wonder about interaction of the neutral (relativistic) beam particles with the charged plasma in the space that the beam passes through. Would there be scattering of particles? Might the beam particles become charged via collisions or via electrons getting entrained?

  8. I would wonder about interaction of the neutral (relativistic) beam particles with the charged plasma in the space that the beam passes through. Would there be scattering of particles? Might the beam particles become charged via collisions or via electrons getting entrained?

  9. You’d never be allowed to build a 50 GW beam system somewhere where it could be pointed at Earth; It would have too much weapons potential. That’s the sort of thing you need to build on the far side of the Moon, or the L2 point. Probably the latter.

  10. A 50 GW beam that can be focused anywhere in the solar system is a useful thing. In between space probe launches it could be used for all manner of stuff. You could even, I imagine, beam power to the Earth. Yes your particles get blocked by the atmosphere, but they have already done their job in getting the light beam all the way to the Earth without spreading.

  11. You’d never be allowed to build a 50 GW beam system somewhere where it could be pointed at Earth; It would have too much weapons potential. That’s the sort of thing you need to build on the far side of the Moon or the L2 point. Probably the latter.

  12. A 50 GW beam that can be focused anywhere in the solar system is a useful thing. In between space probe launches it could be used for all manner of stuff.You could even I imagine beam power to the Earth. Yes your particles get blocked by the atmosphere but they have already done their job in getting the light beam all the way to the Earth without spreading.

  13. Hi, Chris Limbach (PI on the NIAC project) here. I read NBF from time-to-time, so I will try and answer some of the questions. Tom – The particle density of the solar wind is incredibly low at earth’s distance from the sun (several per cubic centimeter), and drops off the farther you go. We have calculated the distance before a collision would be likely, and it is much larger (tens to hundreds of AU) than other limitations on the beam propagation. If there is a collision, the relative velocity is so high both particles would immediately escape the laser trap.

  14. Hi Chris Limbach (PI on the NIAC project) here. I read NBF from time-to-time so I will try and answer some of the questions. Tom – The particle density of the solar wind is incredibly low at earth’s distance from the sun (several per cubic centimeter) and drops off the farther you go. We have calculated the distance before a collision would be likely and it is much larger (tens to hundreds of AU) than other limitations on the beam propagation. If there is a collision the relative velocity is so high both particles would immediately escape the laser trap.

  15. The geopolitical aspects do come up and the far side of the moon is often proposed as a good beamer location for this reason. We are looking at it. Also agree with the optimism on neutral beam cooling!

  16. Appreciate the comment! To maximize energy efficiency we would have to design the system to minimize the particle beam power, as we would throw that away. Very interesting application idea!

  17. Hi Goatguy, Appreciate the comments. We are indeed looking at the photoionization. The lasers we are considering cannot directly photoionize the atoms, as the ionization energy is much larger than the photon energy. However, you can get near-simultaneous multiple absorptions. We are measuring the relevant rate coefficient in the lab as part of Phase I, and right now we believe it will be a fairly low ionization rate and will not provide the main limitation. If there are ions and electrons, the laser actually pushes the electrons OUT of the beam (pondermotive force) which will them generate an ambipolar field pulling the ions out as well. The ions are also not trapped as effectively as the neutrals. As for the energy split, it is not 50/50 and depends on how “good” the particle beams is, i.e. how well collimated it is. You want most of the energy to be in the particle beam because you get much better Thrust/Power compared to the laser.

  18. The geopolitical aspects do come up and the far side of the moon is often proposed as a good beamer location for this reason. We are looking at it. Also agree with the optimism on neutral beam cooling!

  19. Appreciate the comment! To maximize energy efficiency we would have to design the system to minimize the particle beam power as we would throw that away. Very interesting application idea!

  20. Hi GoatguyAppreciate the comments. We are indeed looking at the photoionization. The lasers we are considering cannot directly photoionize the atoms as the ionization energy is much larger than the photon energy. However you can get near-simultaneous multiple absorptions. We are measuring the relevant rate coefficient in the lab as part of Phase I and right now we believe it will be a fairly low ionization rate and will not provide the main limitation. If there are ions and electrons the laser actually pushes the electrons OUT of the beam (pondermotive force) which will them generate an ambipolar field pulling the ions out as well. The ions are also not trapped as effectively as the neutrals. As for the energy split it is not 50/50 and depends on how good”” the particle beams is”””” i.e. how well collimated it is. You want most of the energy to be in the particle beam because you get much better Thrust/Power compared to the laser.”””

  21. SPS proposals generally involve antenna array sizes incapable of producing high energy densities at the Earth’s surface, and deliberately place the phase reference on Earth so that the beam defocuses without active assistance from the target, exactly so that they can’t be used as weapons.

  22. SPS proposals generally involve antenna array sizes incapable of producing high energy densities at the Earth’s surface and deliberately place the phase reference on Earth so that the beam defocuses without active assistance from the target exactly so that they can’t be used as weapons.

  23. Hi Doctorpat, Right now we are focused on investigating the basic physics and making sure we have considered every physical process that might affect the system performance. We have, however, built a mission design tool that we can use to investigate different missions based on the beam power available. We will be submitting this work for publication very soon. Yes, 50 GW is not realistic for near-term missions. Based on this design tool, we believe the cubesat-scale missions could be done with 100 kW – 1 MW, while the outer planet missions (10s of tons at a time) would require order 500 MW and significantly more technology development, especially on the neutral beam source. The application ideas are great and we will definitely be looking at them as the technology moves from concept to reality. Thanks again for your comments.

  24. Hi DoctorpatRight now we are focused on investigating the basic physics and making sure we have considered every physical process that might affect the system performance. We have however built a mission design tool that we can use to investigate different missions based on the beam power available. We will be submitting this work for publication very soon.Yes 50 GW is not realistic for near-term missions. Based on this design tool we believe the cubesat-scale missions could be done with 100 kW – 1 MW while the outer planet missions (10s of tons at a time) would require order 500 MW and significantly more technology development especially on the neutral beam source. The application ideas are great and we will definitely be looking at them as the technology moves from concept to reality. Thanks again for your comments.

  25. Pretty much. More a matter of allowing a software offset from a different phase reference, but, yes, you could design it to focus on a target that wasn’t supplying a phase reference. Limit the antenna array size, though, and hard physics would prevent you focusing it down to intensities suitable for weapons uses. Antenna size is easy to enforce.

  26. Pretty much. More a matter of allowing a software offset from a different phase reference but yes you could design it to focus on a target that wasn’t supplying a phase reference.Limit the antenna array size though and hard physics would prevent you focusing it down to intensities suitable for weapons uses. Antenna size is easy to enforce.

  27. I like your idea for a smaller probe and laser. The probe could just be a set of IC dies. They weight nothing and we can use current IC technology to build them.

  28. Lower the probes mass and increase the beam’s power would increase the acceleration and reduce the distance that the beam has to travel. My suggestion would be to practice with nearby targets like Pluto.

  29. I like your idea for a smaller probe and laser. The probe could just be a set of IC dies. They weight nothing and we can use current IC technology to build them.

  30. Lower the probes mass and increase the beam’s power would increase the acceleration and reduce the distance that the beam has to travel. My suggestion would be to practice with nearby targets like Pluto.

  31. I like your idea for a smaller probe and laser. The probe could just be a set of IC dies. They weight nothing and we can use current IC technology to build them.

  32. I like your idea for a smaller probe and laser. The probe could just be a set of IC dies. They weight nothing and we can use current IC technology to build them.

  33. Lower the probes mass and increase the beam’s power would increase the acceleration and reduce the distance that the beam has to travel. My suggestion would be to practice with nearby targets like Pluto.

  34. Lower the probes mass and increase the beam’s power would increase the acceleration and reduce the distance that the beam has to travel. My suggestion would be to practice with nearby targets like Pluto.

  35. Lower the probes mass and increase the beam’s power would increase the acceleration and reduce the distance that the beam has to travel.

    My suggestion would be to practice with nearby targets like Pluto.

  36. Pretty much. More a matter of allowing a software offset from a different phase reference, but, yes, you could design it to focus on a target that wasn’t supplying a phase reference. Limit the antenna array size, though, and hard physics would prevent you focusing it down to intensities suitable for weapons uses. Antenna size is easy to enforce.

  37. Pretty much. More a matter of allowing a software offset from a different phase reference but yes you could design it to focus on a target that wasn’t supplying a phase reference.Limit the antenna array size though and hard physics would prevent you focusing it down to intensities suitable for weapons uses. Antenna size is easy to enforce.

  38. Pretty much. More a matter of allowing a software offset from a different phase reference, but, yes, you could design it to focus on a target that wasn’t supplying a phase reference.

    Limit the antenna array size, though, and hard physics would prevent you focusing it down to intensities suitable for weapons uses. Antenna size is easy to enforce.

  39. Hi Doctorpat, Right now we are focused on investigating the basic physics and making sure we have considered every physical process that might affect the system performance. We have, however, built a mission design tool that we can use to investigate different missions based on the beam power available. We will be submitting this work for publication very soon. Yes, 50 GW is not realistic for near-term missions. Based on this design tool, we believe the cubesat-scale missions could be done with 100 kW – 1 MW, while the outer planet missions (10s of tons at a time) would require order 500 MW and significantly more technology development, especially on the neutral beam source. The application ideas are great and we will definitely be looking at them as the technology moves from concept to reality. Thanks again for your comments.

  40. Hi DoctorpatRight now we are focused on investigating the basic physics and making sure we have considered every physical process that might affect the system performance. We have however built a mission design tool that we can use to investigate different missions based on the beam power available. We will be submitting this work for publication very soon.Yes 50 GW is not realistic for near-term missions. Based on this design tool we believe the cubesat-scale missions could be done with 100 kW – 1 MW while the outer planet missions (10s of tons at a time) would require order 500 MW and significantly more technology development especially on the neutral beam source. The application ideas are great and we will definitely be looking at them as the technology moves from concept to reality. Thanks again for your comments.

  41. SPS proposals generally involve antenna array sizes incapable of producing high energy densities at the Earth’s surface, and deliberately place the phase reference on Earth so that the beam defocuses without active assistance from the target, exactly so that they can’t be used as weapons.

  42. SPS proposals generally involve antenna array sizes incapable of producing high energy densities at the Earth’s surface and deliberately place the phase reference on Earth so that the beam defocuses without active assistance from the target exactly so that they can’t be used as weapons.

  43. Hi Doctorpat,

    Right now we are focused on investigating the basic physics and making sure we have considered every physical process that might affect the system performance. We have, however, built a mission design tool that we can use to investigate different missions based on the beam power available. We will be submitting this work for publication very soon.

    Yes, 50 GW is not realistic for near-term missions. Based on this design tool, we believe the cubesat-scale missions could be done with 100 kW – 1 MW, while the outer planet missions (10s of tons at a time) would require order 500 MW and significantly more technology development, especially on the neutral beam source.

    The application ideas are great and we will definitely be looking at them as the technology moves from concept to reality. Thanks again for your comments.

  44. The geopolitical aspects do come up and the far side of the moon is often proposed as a good beamer location for this reason. We are looking at it. Also agree with the optimism on neutral beam cooling!

  45. The geopolitical aspects do come up and the far side of the moon is often proposed as a good beamer location for this reason. We are looking at it. Also agree with the optimism on neutral beam cooling!

  46. Appreciate the comment! To maximize energy efficiency we would have to design the system to minimize the particle beam power, as we would throw that away. Very interesting application idea!

  47. Appreciate the comment! To maximize energy efficiency we would have to design the system to minimize the particle beam power as we would throw that away. Very interesting application idea!

  48. Hi Goatguy, Appreciate the comments. We are indeed looking at the photoionization. The lasers we are considering cannot directly photoionize the atoms, as the ionization energy is much larger than the photon energy. However, you can get near-simultaneous multiple absorptions. We are measuring the relevant rate coefficient in the lab as part of Phase I, and right now we believe it will be a fairly low ionization rate and will not provide the main limitation. If there are ions and electrons, the laser actually pushes the electrons OUT of the beam (pondermotive force) which will them generate an ambipolar field pulling the ions out as well. The ions are also not trapped as effectively as the neutrals. As for the energy split, it is not 50/50 and depends on how “good” the particle beams is, i.e. how well collimated it is. You want most of the energy to be in the particle beam because you get much better Thrust/Power compared to the laser.

  49. Hi GoatguyAppreciate the comments. We are indeed looking at the photoionization. The lasers we are considering cannot directly photoionize the atoms as the ionization energy is much larger than the photon energy. However you can get near-simultaneous multiple absorptions. We are measuring the relevant rate coefficient in the lab as part of Phase I and right now we believe it will be a fairly low ionization rate and will not provide the main limitation. If there are ions and electrons the laser actually pushes the electrons OUT of the beam (pondermotive force) which will them generate an ambipolar field pulling the ions out as well. The ions are also not trapped as effectively as the neutrals. As for the energy split it is not 50/50 and depends on how good”” the particle beams is”””” i.e. how well collimated it is. You want most of the energy to be in the particle beam because you get much better Thrust/Power compared to the laser.”””

  50. Hi, Chris Limbach (PI on the NIAC project) here. I read NBF from time-to-time, so I will try and answer some of the questions. Tom – The particle density of the solar wind is incredibly low at earth’s distance from the sun (several per cubic centimeter), and drops off the farther you go. We have calculated the distance before a collision would be likely, and it is much larger (tens to hundreds of AU) than other limitations on the beam propagation. If there is a collision, the relative velocity is so high both particles would immediately escape the laser trap.

  51. Hi Chris Limbach (PI on the NIAC project) here. I read NBF from time-to-time so I will try and answer some of the questions. Tom – The particle density of the solar wind is incredibly low at earth’s distance from the sun (several per cubic centimeter) and drops off the farther you go. We have calculated the distance before a collision would be likely and it is much larger (tens to hundreds of AU) than other limitations on the beam propagation. If there is a collision the relative velocity is so high both particles would immediately escape the laser trap.

  52. SPS proposals generally involve antenna array sizes incapable of producing high energy densities at the Earth’s surface, and deliberately place the phase reference on Earth so that the beam defocuses without active assistance from the target, exactly so that they can’t be used as weapons.

  53. You’d never be allowed to build a 50 GW beam system somewhere where it could be pointed at Earth; It would have too much weapons potential. That’s the sort of thing you need to build on the far side of the Moon, or the L2 point. Probably the latter.

  54. You’d never be allowed to build a 50 GW beam system somewhere where it could be pointed at Earth; It would have too much weapons potential. That’s the sort of thing you need to build on the far side of the Moon or the L2 point. Probably the latter.

  55. Hi Goatguy,

    Appreciate the comments. We are indeed looking at the photoionization. The lasers we are considering cannot directly photoionize the atoms, as the ionization energy is much larger than the photon energy. However, you can get near-simultaneous multiple absorptions. We are measuring the relevant rate coefficient in the lab as part of Phase I, and right now we believe it will be a fairly low ionization rate and will not provide the main limitation. If there are ions and electrons, the laser actually pushes the electrons OUT of the beam (pondermotive force) which will them generate an ambipolar field pulling the ions out as well. The ions are also not trapped as effectively as the neutrals.

    As for the energy split, it is not 50/50 and depends on how “good” the particle beams is, i.e. how well collimated it is. You want most of the energy to be in the particle beam because you get much better Thrust/Power compared to the laser.

  56. Hi, Chris Limbach (PI on the NIAC project) here. I read NBF from time-to-time, so I will try and answer some of the questions.

    Tom – The particle density of the solar wind is incredibly low at earth’s distance from the sun (several per cubic centimeter), and drops off the farther you go. We have calculated the distance before a collision would be likely, and it is much larger (tens to hundreds of AU) than other limitations on the beam propagation. If there is a collision, the relative velocity is so high both particles would immediately escape the laser trap.

  57. A 50 GW beam that can be focused anywhere in the solar system is a useful thing. In between space probe launches it could be used for all manner of stuff. You could even, I imagine, beam power to the Earth. Yes your particles get blocked by the atmosphere, but they have already done their job in getting the light beam all the way to the Earth without spreading.

  58. A 50 GW beam that can be focused anywhere in the solar system is a useful thing. In between space probe launches it could be used for all manner of stuff.You could even I imagine beam power to the Earth. Yes your particles get blocked by the atmosphere but they have already done their job in getting the light beam all the way to the Earth without spreading.

  59. I would wonder about interaction of the neutral (relativistic) beam particles with the charged plasma in the space that the beam passes through. Would there be scattering of particles? Might the beam particles become charged via collisions or via electrons getting entrained?

  60. I would wonder about interaction of the neutral (relativistic) beam particles with the charged plasma in the space that the beam passes through. Would there be scattering of particles? Might the beam particles become charged via collisions or via electrons getting entrained?

  61. I’m fairly optimistic about neutral mass beams; If you use laser cooling on the beam to reduce the perpendicular component of the temperature, you can get the divergence down to an absurdly low level. Especially if you have stations along the beam refocusing it every 10th of a light year or so. But I really prefer the use of “particles” in the mass beam that are large enough to have their own guidance and propulsion systems.

  62. I’m fairly optimistic about neutral mass beams; If you use laser cooling on the beam to reduce the perpendicular component of the temperature you can get the divergence down to an absurdly low level. Especially if you have stations along the beam refocusing it every 10th of a light year or so.But I really prefer the use of particles”” in the mass beam that are large enough to have their own guidance and propulsion systems.”””

  63. You’d never be allowed to build a 50 GW beam system somewhere where it could be pointed at Earth; It would have too much weapons potential. That’s the sort of thing you need to build on the far side of the Moon, or the L2 point. Probably the latter.

  64. I don’t know… it kind of sounds like magic to me. Ionized beams just want to diverge. Internal electrostatic charges of neighboring ions — even if their pretty far away, like meters — tends to diverge ionized beams. Neutral beams tend to diverge because of much smaller brownian collision or if you will “gas pressure’ forces. Granted, a gigawatt beam, 5 m² in cross section, isn’t going to have a whole lot of gas pressure. But it’ll have some! Laser beams tend to diverge because of their source-side fundamental divergence. Doesn’t matter (much) how wide or narrow the beam is, the quality of the final mirror which collimates the beam to its final form imparts an irreducible amount of divergence in the beam. But I guess the idea is, by combining the two, the index-of-refraction of a long straight whisp of neutral ions will have — not unlike a communications graded-index fiber-optic cable — a graded index of refraction, which in turn will tend to keep the passing light centered on the beam, not escaping the core … due to “perfect internal reflection” optical phenomena. Got that part! Question is, what force(s) in turn work to keep the ion beam collimated? Hmmm… I suppose the light could very infrequently ionize neutral atoms. The ion-pairs, positive charged nuclei and negative charged electrons would go flying apart, but as I said about electrostatic forces working over meters when given enough time, the ions would “feel the attraction” of their opposite member closeby. And would tend to recombine. And the highest density of ions would therefore be near the center of the neutral beam. The not-so-neutral beam. Thing is, this wouldn’t necessarily tend to confine the neutral part of the beam. Hmmm… have to think about that more. _______ A 50 GW combined energy beam is something pretty special. What’s the split. 50:50? I should go read the detailed article. Not much time left. In any case, 50 GW is a LOT of power to be swinging around in orbit s

  65. I don’t know… it kind of sounds like magic to me. Ionized beams just want to diverge. Internal electrostatic charges of neighboring ions — even if their pretty far away like meters — tends to diverge ionized beams. Neutral beams tend to diverge because of much smaller brownian collision or if you will gas pressure’ forces. Granted” a gigawatt beam 5 m² in cross section isn’t going to have a whole lot of gas pressure. But it’ll have some!Laser beams tend to diverge because of their source-side fundamental divergence. Doesn’t matter (much) how wide or narrow the beam is the quality of the final mirror which collimates the beam to its final form imparts an irreducible amount of divergence in the beam. But I guess the idea is by combining the two the index-of-refraction of a long straight whisp of neutral ions will have — not unlike a communications graded-index fiber-optic cable — a graded index of refraction which in turn will tend to keep the passing light centered on the beam” not escaping the core … due to “”perfect internal reflection”””” optical phenomena. Got that part!Question is”” what force(s) in turn work to keep the ion beam collimated? Hmmm… I suppose the light could very infrequently ionize neutral atoms. The ion-pairs positive charged nuclei and negative charged electrons would go flying apart but as I said about electrostatic forces working over meters when given enough time”” the ions would “”””feel the attraction”””” of their opposite member closeby. And would tend to recombine. And the highest density of ions would therefore be near the center of the neutral beam. The not-so-neutral beam. Thing is”” this wouldn’t necessarily tend to confine the neutral part of the beam. Hmmm… have to think about that more. _______A 50 GW combined energy beam is something pretty special. What’s the split. 50:50? I should go read the detailed article. Not much time left.In any case 50 GW is a LOT of power to be swing”

  66. Sounds promising. Note that the difference in velocity between the light and the particles would tend to suppress instabilities.

  67. Sounds promising. Note that the difference in velocity between the light and the particles would tend to suppress instabilities.

  68. A 50 GW beam that can be focused anywhere in the solar system is a useful thing. In between space probe launches it could be used for all manner of stuff.

    You could even, I imagine, beam power to the Earth. Yes your particles get blocked by the atmosphere, but they have already done their job in getting the light beam all the way to the Earth without spreading.

  69. I would wonder about interaction of the neutral (relativistic) beam particles with the charged plasma in the space that the beam passes through.
    Would there be scattering of particles? Might the beam particles become charged via collisions or via electrons getting entrained?

  70. I’m fairly optimistic about neutral mass beams; If you use laser cooling on the beam to reduce the perpendicular component of the temperature, you can get the divergence down to an absurdly low level. Especially if you have stations along the beam refocusing it every 10th of a light year or so.

    But I really prefer the use of “particles” in the mass beam that are large enough to have their own guidance and propulsion systems.

  71. I don’t know… it kind of sounds like magic to me. Ionized beams just want to diverge. Internal electrostatic charges of neighboring ions — even if their pretty far away, like meters — tends to diverge ionized beams.

    Neutral beams tend to diverge because of much smaller brownian collision or if you will “gas pressure’ forces. Granted, a gigawatt beam, 5 m² in cross section, isn’t going to have a whole lot of gas pressure. But it’ll have some!

    Laser beams tend to diverge because of their source-side fundamental divergence. Doesn’t matter (much) how wide or narrow the beam is, the quality of the final mirror which collimates the beam to its final form imparts an irreducible amount of divergence in the beam.

    But I guess the idea is, by combining the two, the index-of-refraction of a long straight whisp of neutral ions will have — not unlike a communications graded-index fiber-optic cable — a graded index of refraction, which in turn will tend to keep the passing light centered on the beam, not escaping the core … due to “perfect internal reflection” optical phenomena. Got that part!

    Question is, what force(s) in turn work to keep the ion beam collimated? Hmmm… I suppose the light could very infrequently ionize neutral atoms. The ion-pairs, positive charged nuclei and negative charged electrons would go flying apart, but as I said about electrostatic forces working over meters when given enough time, the ions would “feel the attraction” of their opposite member closeby. And would tend to recombine.

    And the highest density of ions would therefore be near the center of the neutral beam. The not-so-neutral beam. Thing is, this wouldn’t necessarily tend to confine the neutral part of the beam. Hmmm… have to think about that more.
    _______

    A 50 GW combined energy beam is something pretty special. What’s the split. 50:50? I should go read the detailed article. Not much time left.

    In any case, 50 GW is a LOT of power to be swinging around in orbit someplace. Someplace where getting the driving power isn’t as challenged as it is at Earth’s orbit. Say Mercury’s? One of the Trojan high-stability points? Having a distance of only 0.4 AU, insolation is 6× higher. 8,500 W/m² … figuring 25% multilayer efficiency and what, maybe 15% output-versus-input power then

    50,000,000,000 W / (0.25 × 0.15) → 1,330 GW
    1,330,000,000 kW ÷ 8.5 kW/m² → 150,000,000 m² solar array
    √( 150×10⁶ ) → 12.5 km on a side.

    Wowzers. That’s huge. Dwarfs all Human solar panel production, globe-wide, to date. Every bit of it.

    And all this to send ONE flipping midget of spacecraft to Proxima Centauri? For a 10%-of-lightspeed flyby? Of a spacecraft weighing in at 1 kg?

    Tell me… what kind of optics is going to be aboard a 1 kg spacecraft … that’s mostly “collector sail” for the particle and luminous beams? Seriously! And its not like it can shed the umbrella. Got to “ET Phone Home” too!!!

    GoatGuy

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