Pulsed fission fusion rocket for 37 days to Mars and other missions

The pulsed fission fusion propulsion (PuFF) system envisions using a pulsed z-pinch to compress a fission-fusion target.

2 mega-amps would be sent through a uranium-deuterium-tritium target.
The uranium would fission first and then it would trigger a fusion reaction.

The resulting deflagration expands against a magnetic nozzle to produce thrust and generate recharge energy for the next pulse. A z-Pinch is a device that is commonly used to compress laboratory plasmas to high pressures (~1 Mbar) for very short timescales (~100 ns). An electrical discharge produces a high axial current along the outer surface of a column of plasma; this current in turn generates a very strong toroidal magnetic field. This self-generated magnetic field interacts with the axial current via the Lorentz force and radially compresses the plasma column, bringing it to very high densities and temperatures. This team is exploring a modified Z-pinch geometry as a propulsion system by encasing the fission-fusion target in a sheath of liquid lithium, providing a current return path. Numerical results have been promising, the level of compression is sufficient to reach fission criticality. The fission energy boosts the fusion reaction rate, generating more neutrons which boost the fission process. This concept will potentially reach specific impulses of 90,000 sec with thrust levels sufficient to travel to Mars in a month and to interstellar space in a few decades.

There was a presentation from 2017.

125 thoughts on “Pulsed fission fusion rocket for 37 days to Mars and other missions”

  1. If you’ve got a propulsion system like that, you’d be far better off reaching Mars in 7 months with an enormously larger payload. Because you could carry enough payload to provide more than adequate radiation shielding for the crew.

    Reply
  2. If you’ve got a propulsion system like that you’d be far better off reaching Mars in 7 months with an enormously larger payload. Because you could carry enough payload to provide more than adequate radiation shielding for the crew.

    Reply
  3. Just got to love the physics. First… we fill up a ship full of deuterium-tritium-uranium targets. Then… we feed them at 100 Hz into each blast chamber Then… we blast each with a 2,000,000 amp, 2,000,000 volt pulse Which… explodes the little cores. Fission, Fusion, ejecta. Then… that’s captured by the magnetic nozzle, which Deflects… the particles making thrust And… makes a pulse of current, recharging the capacitors. To… start it all over again. MAKING… sufficient thrust to “do the Kessel Run in less than 3 parsecs”. Ahem… the Earth↔Mars run in 37 days. The ISP is to be 90,000, reaction-mass velocity of 9.81× that. 883 km/s. The rocket weighs how much again? Well … wasn’t stated. But let’s guess (starts a spreadsheet, goes away for awhile…) OK, back. If fuel is 16.7% of the ship mass, If 27% fuel-use-up is performed to accelerate out to Mars, If 25.8% fuel-use-up is used to decelerate If ISP is 90,000 (883 km/s) If 30,000 kg is the ship mass incl. fuel at launch If acceleration is concentrated in first 10% of trip (3.7 days) If deceleration is ocncentrated in last 9.5% of trip THEN the ship will attain a speed of 40.6 km/s Which when drifting for 29.8 days… Goes about 0.78 AU. And there you are!!! _______ Only remaining details are solveable by intrepid post-Grad students. Little things like how fast a burn rate (4.2 g/sec), exhaust energy 1.6 gigawatts, whether enough ²³⁵U could fission (4.1%), amount of waste heat — radiant and impact-from-neutrons heat, 90% or 1,300,000,000 W to contend with on the nozzle-end of things. Just saying, goats. By no means as glibly doable as is let on to be. Just saying, [b]Goat[/b]Guy

    Reply
  4. By the way, it’s been obvious for a long, long time that you could do this, the obstacle is really regulatory, not so much technology.

    Reply
  5. I’ve had a NIAC grant and its never assumed anything is glibly”” doable. NIAC grants are speculative by definition.”””

    Reply
  6. Just got to love the physics. First… we fill up a ship full of deuterium-tritium-uranium targets. Then… we feed them at 100 Hz into each blast chamberThen… we blast each with a 2000000 amp 2000000 volt pulseWhich… explodes the little cores. Fission Fusion ejecta.Then… that’s captured by the magnetic nozzle whichDeflects… the particles making thrustAnd… makes a pulse of current recharging the capacitors.To… start it all over again. MAKING… sufficient thrust to do the Kessel Run in less than 3 parsecs””. Ahem… the Earth↔Mars run in 37 days. The ISP is to be 90″”0 reaction-mass velocity of 9.81× that. 883 km/s.The rocket weighs how much again? Well … wasn’t stated. But let’s guess (starts a spreadsheet goes away for awhile…)OK back.If fuel is 16.7{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of the ship mass If 27{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} fuel-use-up is performed to accelerate out to MarsIf 25.8{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} fuel-use-up is used to decelerateIf ISP is 90000 (883 km/s)If 30000 kg is the ship mass incl. fuel at launchIf acceleration is concentrated in first 10{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of trip (3.7 days)If deceleration is ocncentrated in last 9.5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of tripTHEN the ship will attain a speed of 40.6 km/sWhich when drifting for 29.8 days… Goes about 0.78 AU. And there you are!!!_______Only remaining details are solveable by intrepid post-Grad students. Little things like how fast a burn rate (4.2 g/sec) exhaust energy 1.6 gigawatts whether enough ²³⁵U could fission (4.1{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12}) amount of waste heat — radiant and impact-from-neutrons heat 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} or 13000000 W to con”

    Reply
  7. By the way it’s been obvious for a long long time that you could do this the obstacle is really regulatory not so much technology.

    Reply
  8. RadicalModerate one time did an ideal gas calc with uranium at giga-pascals of pressure and argued that the density of the uranium could be made hundreds of grams per cc and that this could, you know, do what they are saying here (blow up). Well, if that works and we can fission a hundred milligrams at a time then space travel is on. So, what has been obvious for a long time? That ultra condensed matter physics makes sub gram bombs possible? I’ve been following Z-machine since the early 2000s. News out of there is pretty scarce – it’s been a letdown like NIF. Yet another possibility limited by lack of ability to deliver 50MJ in a nanosecond.

    Reply
  9. The biosphere doesn’t typically care about levels of radioactive pollution that humans could achieve over significant areas without resorting to large numbers of cobalt clad neutron bombs. The biosphere wouldn’t even notice this being used in near Earth space.

    Reply
  10. RadicalModerate one time did an ideal gas calc with uranium at giga-pascals of pressure and argued that the density of the uranium could be made hundreds of grams per cc and that this could you know do what they are saying here (blow up).Well if that works and we can fission a hundred milligrams at a time then space travel is on. So what has been obvious for a long time? That ultra condensed matter physics makes sub gram bombs possible? I’ve been following Z-machine since the early 2000s. News out of there is pretty scarce – it’s been a letdown like NIF. Yet another possibility limited by lack of ability to deliver 50MJ in a nanosecond.

    Reply
  11. The biosphere doesn’t typically care about levels of radioactive pollution that humans could achieve over significant areas without resorting to large numbers of cobalt clad neutron bombs. The biosphere wouldn’t even notice this being used in near Earth space.

    Reply
  12. The whole point (though never explicitly stated that I can see) is that it is thought/hoped to be much easier to get the fission-fusion reaction to start than a pure fusion. So much easier that it is possible to ignite the reactions without needing a laser system the size of a town. Given that people have been trying to get fusion to work (at a scale where energy out> energy in) for over half a century, it may well be that it would be insisting on pure fusion that would make sure the concept never gets anywhere.

    Reply
  13. And, as with the Kessel Run, it is possible to measure the speed of the run by measuring the travel DISTANCE. The more effective your space drive, the shorter your travel distance. A continuous 6g acceleration is just about a straight line when the two planets are in conjunction. The really slow ships have to spiral out over half an orbit or more.

    Reply
  14. Clean lithium fission rocket”” on NASASpaceFlight March 2016?Discussion of L6 —> proton”” triton”” and helium fragments.”””

    Reply
  15. The whole point (though never explicitly stated that I can see) is that it is thought/hoped to be much easier to get the fission-fusion reaction to start than a pure fusion. So much easier that it is possible to ignite the reactions without needing a laser system the size of a town.Given that people have been trying to get fusion to work (at a scale where energy out> energy in) for over half a century it may well be that it would be insisting on pure fusion that would make sure the concept never gets anywhere.

    Reply
  16. And as with the Kessel Run it is possible to measure the speed of the run by measuring the travel DISTANCE.The more effective your space drive the shorter your travel distance. A continuous 6g acceleration is just about a straight line when the two planets are in conjunction. The really slow ships have to spiral out over half an orbit or more.

    Reply
  17. On a side note, you can make sense of the movie line, if you just understand him to be bragging about taking some shortcuts anybody else would view as insanely dangerous. “I went straight through it!” Through, realistically, somebody just thought a parsec was a unit of time, it can be fun trying to rationalize movie mistakes.

    Reply
  18. Sure the various fusion projects all HOPE to achieve net positive fusion. But as yet the only proven ways to achieve this is via a fission trigger (ie. a Hydrogen bomb) or by having a mass the size of a star.

    Reply
  19. Exactly right. However, using another astrophysics model (not our sun) in this case pulsars and neutron stars, the temperature for boron proton fusion seems to have been consistently, repeatably, achieved : ( from: (PDF) Fusion reactions from >150 keV ions in a dense plasma focus. plasmoid.https://www.researchgate.net/publication/236221996_Fusion_reactions_from_150_keV_ions_in_a_dense_plasma_focus_plasmoid) “Using a dense plasma focus device with a 50 kJ capacitor charge, we have observed fusion reactions from deuterium ions with record energies of >150 keV, which are confined for durations of 7–30 ns in the cores of plasmoids with typical radii of 300–500 μm and densities ∼3 × 1019 cm−3. We have for the first time simultaneously imaged the plasmoid at high (30 μm) resolution and measured trapped ion energy and neutron anisotropy. The isotropy of the neutron emission as well as other observations confirms that the observed neutrons per pulse of up to 1.5 × 1011 are produced mainly by confined ions, not an unconfined beam. The conditions achieved are of interest for aneutronic fusion, such as with pB11 fuel. ” and then from: https://lppfusion.com/space-propulsion/ ” In space, Focus Fusion could provide not just power, but propulsion as well. Focus Fusion generates a beam of ions that accelerates rapidly away from the central anode, and by rapidly we mean at around a thousand kilometers per second! That works out to around one million seconds of specific impulse, a measure of rocket engine efficiency. So every Focus Fusion generator also happens to be an ultra-efficient rocket. … If more thrust is desired, Focus Fusion’s power output could be modified or combined with power-hungry propulsion systems such as……..”

    Reply
  20. On a side note you can make sense of the movie line if you just understand him to be bragging about taking some shortcuts anybody else would view as insanely dangerous. I went straight through it!”” Through”” realistically somebody just thought a parsec was a unit of time”” it can be fun trying to rationalize movie mistakes.”””

    Reply
  21. Sure the various fusion projects all HOPE to achieve net positive fusion. But as yet the only proven ways to achieve this is via a fission trigger (ie. a Hydrogen bomb) or by having a mass the size of a star.

    Reply
  22. Exactly right. However using another astrophysics model (not our sun) in this case pulsars and neutron stars the temperature for boron proton fusion seems to have been consistently repeatably achieved : ( from: (PDF) Fusion reactions from >150 keV ions in a dense plasma focus. plasmoid.https://www.researchgate.net/publication/236221996_Fusion_reactions_from_150_keV_ions_in_a_dense_plasma_focus_plasmoid)Using a dense plasma focus device with a 50 kJ capacitor charge” we have observed fusion reactions from deuterium ions with record energies of >150 keV which are confined for durations of 7–30 ns in the cores of plasmoids with typical radii of 300–500 μm and densities ∼3 × 1019 cm−3. We have for the first time simultaneously imaged the plasmoid at high (30 μm) resolution and measured trapped ion energy and neutron anisotropy. The isotropy of the neutron emission as well as other observations confirms that the observed neutrons per pulse of up to 1.5 × 1011 are produced mainly by confined ions not an unconfined beam. The conditions achieved are of interest for aneutronic fusion” such as with pB11 fuel. “”and then from: https://lppfusion.com/space-propulsion/“””” In space”” Focus Fusion could provide not just power but propulsion as well. Focus Fusion generates a beam of ions that accelerates rapidly away from the central anode and by rapidly we mean at around a thousand kilometers per second! That works out to around one million seconds of specific impulse a measure of rocket engine efficiency. So every Focus Fusion generator also happens to be an ultra-efficient rocket. …If more thrust is desired”” Focus Fusion’s power output could be modified or combined with power-hungry propulsion systems such as……..”””””””””””

    Reply
  23. Umm, you’re saying humans would need to endure continuous 4.2 G’s for 3.7 days in order to make the trip in the time promised? And a similar deceleration at the end? That certainly would not be fun.

    Reply
  24. Umm you’re saying humans would need to endure continuous 4.2 G’s for 3.7 days in order to make the trip in the time promised? And a similar deceleration at the end? That certainly would not be fun.

    Reply
  25. Per GoatGuy’s numbers: 3.7 days of acceleration is ~320000 s. Top speed is ~40000 m/s. Hence acceleration is ~8 m/s^2, or just under 1 G.

    Reply
  26. Per GoatGuy’s numbers: 3.7 days of acceleration is ~320000 s. Top speed is ~40000 m/s. Hence acceleration is ~8 m/s^2 or just under 1 G.

    Reply
  27. Thanks Scary. People like you (talking about your colleagues as well) should be working for Boeing, Northrop, Lockheed or Spacex and making over 200K a year. I have a friend just like that who works for Northrop.

    Reply
  28. Thanks Scary. People like you (talking about your colleagues as well) should be working for Boeing Northrop Lockheed or Spacex and making over 200K a year. I have a friend just like that who works for Northrop.

    Reply
  29. You seem to be talking about solid-core nuclear thermal rockets. You understand that at some point, the reactor heat exceeds the physical (“These could use unbelievably high injection pressures”) and temperature limits of the core materials and reactor structure? That’s what a meltdown is, after all. And there’s drag (“and incredibly long super-heating tubes .”), plus the fact that a fission reactor can’t have any arbitrary geometry, if you don’t want to waste reaction-sustaining neutrons. Now, one could have gas-core NTRs, but that has a whole different set of problems when you *let* the uranium go ahead and vaporize itself, and try to heat a reaction mass with it, and expel that mass without losing the fission fuel…

    Reply
  30. You seem to be talking about solid-core nuclear thermal rockets.You understand that at some point the reactor heat exceeds the physical (These could use unbelievably high injection pressures””) and temperature limits of the core materials and reactor structure? That’s what a meltdown is”””” after all.And there’s drag (“”””and incredibly long super-heating tubes .””””)”” plus the fact that a fission reactor can’t have any arbitrary geometry if you don’t want to waste reaction-sustaining neutrons.Now one could have gas-core NTRs but that has a whole different set of problems when you *let* the uranium go ahead and vaporize itself and try to heat a reaction mass with it”” and expel that mass without losing the fission fuel…”””

    Reply
  31. You seem to be talking about solid-core nuclear thermal rockets. You understand that at some point, the reactor heat exceeds the physical (“These could use unbelievably high injection pressures”) and temperature limits of the core materials and reactor structure? That’s what a meltdown is, after all. And there’s drag (“and incredibly long super-heating tubes .”), plus the fact that a fission reactor can’t have any arbitrary geometry, if you don’t want to waste reaction-sustaining neutrons. Now, one could have gas-core NTRs, but that has a whole different set of problems when you *let* the uranium go ahead and vaporize itself, and try to heat a reaction mass with it, and expel that mass without losing the fission fuel…

    Reply
  32. You seem to be talking about solid-core nuclear thermal rockets.You understand that at some point the reactor heat exceeds the physical (These could use unbelievably high injection pressures””) and temperature limits of the core materials and reactor structure? That’s what a meltdown is”””” after all.And there’s drag (“”””and incredibly long super-heating tubes .””””)”” plus the fact that a fission reactor can’t have any arbitrary geometry if you don’t want to waste reaction-sustaining neutrons.Now one could have gas-core NTRs but that has a whole different set of problems when you *let* the uranium go ahead and vaporize itself and try to heat a reaction mass with it”” and expel that mass without losing the fission fuel…”””

    Reply
  33. You seem to be talking about solid-core nuclear thermal rockets.

    You understand that at some point, the reactor heat exceeds the physical (“These could use unbelievably high injection pressures”) and temperature limits of the core materials and reactor structure? That’s what a meltdown is, after all.

    And there’s drag (“and incredibly long super-heating tubes .”), plus the fact that a fission reactor can’t have any arbitrary geometry, if you don’t want to waste reaction-sustaining neutrons.

    Now, one could have gas-core NTRs, but that has a whole different set of problems when you *let* the uranium go ahead and vaporize itself, and try to heat a reaction mass with it, and expel that mass without losing the fission fuel…

    Reply
  34. Thanks Scary. People like you (talking about your colleagues as well) should be working for Boeing, Northrop, Lockheed or Spacex and making over 200K a year. I have a friend just like that who works for Northrop.

    Reply
  35. Thanks Scary. People like you (talking about your colleagues as well) should be working for Boeing Northrop Lockheed or Spacex and making over 200K a year. I have a friend just like that who works for Northrop.

    Reply
  36. Thanks Scary. People like you (talking about your colleagues as well) should be working for Boeing, Northrop, Lockheed or Spacex and making over 200K a year. I have a friend just like that who works for Northrop.

    Reply
  37. Per GoatGuy’s numbers: 3.7 days of acceleration is ~320000 s. Top speed is ~40000 m/s. Hence acceleration is ~8 m/s^2, or just under 1 G.

    Reply
  38. Per GoatGuy’s numbers: 3.7 days of acceleration is ~320000 s. Top speed is ~40000 m/s. Hence acceleration is ~8 m/s^2 or just under 1 G.

    Reply
  39. Umm, you’re saying humans would need to endure continuous 4.2 G’s for 3.7 days in order to make the trip in the time promised? And a similar deceleration at the end? That certainly would not be fun.

    Reply
  40. Umm you’re saying humans would need to endure continuous 4.2 G’s for 3.7 days in order to make the trip in the time promised? And a similar deceleration at the end? That certainly would not be fun.

    Reply
  41. Umm, you’re saying humans would need to endure continuous 4.2 G’s for 3.7 days in order to make the trip in the time promised? And a similar deceleration at the end? That certainly would not be fun.

    Reply
  42. On a side note, you can make sense of the movie line, if you just understand him to be bragging about taking some shortcuts anybody else would view as insanely dangerous. “I went straight through it!” Through, realistically, somebody just thought a parsec was a unit of time, it can be fun trying to rationalize movie mistakes.

    Reply
  43. On a side note you can make sense of the movie line if you just understand him to be bragging about taking some shortcuts anybody else would view as insanely dangerous. I went straight through it!”” Through”” realistically somebody just thought a parsec was a unit of time”” it can be fun trying to rationalize movie mistakes.”””

    Reply
  44. Sure the various fusion projects all HOPE to achieve net positive fusion. But as yet the only proven ways to achieve this is via a fission trigger (ie. a Hydrogen bomb) or by having a mass the size of a star.

    Reply
  45. Sure the various fusion projects all HOPE to achieve net positive fusion. But as yet the only proven ways to achieve this is via a fission trigger (ie. a Hydrogen bomb) or by having a mass the size of a star.

    Reply
  46. Exactly right. However, using another astrophysics model (not our sun) in this case pulsars and neutron stars, the temperature for boron proton fusion seems to have been consistently, repeatably, achieved : ( from: (PDF) Fusion reactions from >150 keV ions in a dense plasma focus. plasmoid.https://www.researchgate.net/publication/236221996_Fusion_reactions_from_150_keV_ions_in_a_dense_plasma_focus_plasmoid) “Using a dense plasma focus device with a 50 kJ capacitor charge, we have observed fusion reactions from deuterium ions with record energies of >150 keV, which are confined for durations of 7–30 ns in the cores of plasmoids with typical radii of 300–500 μm and densities ∼3 × 1019 cm−3. We have for the first time simultaneously imaged the plasmoid at high (30 μm) resolution and measured trapped ion energy and neutron anisotropy. The isotropy of the neutron emission as well as other observations confirms that the observed neutrons per pulse of up to 1.5 × 1011 are produced mainly by confined ions, not an unconfined beam. The conditions achieved are of interest for aneutronic fusion, such as with pB11 fuel. ” and then from: https://lppfusion.com/space-propulsion/ ” In space, Focus Fusion could provide not just power, but propulsion as well. Focus Fusion generates a beam of ions that accelerates rapidly away from the central anode, and by rapidly we mean at around a thousand kilometers per second! That works out to around one million seconds of specific impulse, a measure of rocket engine efficiency. So every Focus Fusion generator also happens to be an ultra-efficient rocket. … If more thrust is desired, Focus Fusion’s power output could be modified or combined with power-hungry propulsion systems such as……..”

    Reply
  47. Exactly right. However using another astrophysics model (not our sun) in this case pulsars and neutron stars the temperature for boron proton fusion seems to have been consistently repeatably achieved : ( from: (PDF) Fusion reactions from >150 keV ions in a dense plasma focus. plasmoid.https://www.researchgate.net/publication/236221996_Fusion_reactions_from_150_keV_ions_in_a_dense_plasma_focus_plasmoid)Using a dense plasma focus device with a 50 kJ capacitor charge” we have observed fusion reactions from deuterium ions with record energies of >150 keV which are confined for durations of 7–30 ns in the cores of plasmoids with typical radii of 300–500 μm and densities ∼3 × 1019 cm−3. We have for the first time simultaneously imaged the plasmoid at high (30 μm) resolution and measured trapped ion energy and neutron anisotropy. The isotropy of the neutron emission as well as other observations confirms that the observed neutrons per pulse of up to 1.5 × 1011 are produced mainly by confined ions not an unconfined beam. The conditions achieved are of interest for aneutronic fusion” such as with pB11 fuel. “”and then from: https://lppfusion.com/space-propulsion/“””” In space”” Focus Fusion could provide not just power but propulsion as well. Focus Fusion generates a beam of ions that accelerates rapidly away from the central anode and by rapidly we mean at around a thousand kilometers per second! That works out to around one million seconds of specific impulse a measure of rocket engine efficiency. So every Focus Fusion generator also happens to be an ultra-efficient rocket. …If more thrust is desired”” Focus Fusion’s power output could be modified or combined with power-hungry propulsion systems such as……..”””””””””””

    Reply
  48. Clean lithium fission rocket”” on NASASpaceFlight March 2016?Discussion of L6 —> proton”” triton”” and helium fragments.”””

    Reply
  49. The whole point (though never explicitly stated that I can see) is that it is thought/hoped to be much easier to get the fission-fusion reaction to start than a pure fusion. So much easier that it is possible to ignite the reactions without needing a laser system the size of a town. Given that people have been trying to get fusion to work (at a scale where energy out> energy in) for over half a century, it may well be that it would be insisting on pure fusion that would make sure the concept never gets anywhere.

    Reply
  50. The whole point (though never explicitly stated that I can see) is that it is thought/hoped to be much easier to get the fission-fusion reaction to start than a pure fusion. So much easier that it is possible to ignite the reactions without needing a laser system the size of a town.Given that people have been trying to get fusion to work (at a scale where energy out> energy in) for over half a century it may well be that it would be insisting on pure fusion that would make sure the concept never gets anywhere.

    Reply
  51. And, as with the Kessel Run, it is possible to measure the speed of the run by measuring the travel DISTANCE. The more effective your space drive, the shorter your travel distance. A continuous 6g acceleration is just about a straight line when the two planets are in conjunction. The really slow ships have to spiral out over half an orbit or more.

    Reply
  52. And as with the Kessel Run it is possible to measure the speed of the run by measuring the travel DISTANCE.The more effective your space drive the shorter your travel distance. A continuous 6g acceleration is just about a straight line when the two planets are in conjunction. The really slow ships have to spiral out over half an orbit or more.

    Reply
  53. RadicalModerate one time did an ideal gas calc with uranium at giga-pascals of pressure and argued that the density of the uranium could be made hundreds of grams per cc and that this could, you know, do what they are saying here (blow up). Well, if that works and we can fission a hundred milligrams at a time then space travel is on. So, what has been obvious for a long time? That ultra condensed matter physics makes sub gram bombs possible? I’ve been following Z-machine since the early 2000s. News out of there is pretty scarce – it’s been a letdown like NIF. Yet another possibility limited by lack of ability to deliver 50MJ in a nanosecond.

    Reply
  54. RadicalModerate one time did an ideal gas calc with uranium at giga-pascals of pressure and argued that the density of the uranium could be made hundreds of grams per cc and that this could you know do what they are saying here (blow up).Well if that works and we can fission a hundred milligrams at a time then space travel is on. So what has been obvious for a long time? That ultra condensed matter physics makes sub gram bombs possible? I’ve been following Z-machine since the early 2000s. News out of there is pretty scarce – it’s been a letdown like NIF. Yet another possibility limited by lack of ability to deliver 50MJ in a nanosecond.

    Reply
  55. The biosphere doesn’t typically care about levels of radioactive pollution that humans could achieve over significant areas without resorting to large numbers of cobalt clad neutron bombs. The biosphere wouldn’t even notice this being used in near Earth space.

    Reply
  56. The biosphere doesn’t typically care about levels of radioactive pollution that humans could achieve over significant areas without resorting to large numbers of cobalt clad neutron bombs. The biosphere wouldn’t even notice this being used in near Earth space.

    Reply
  57. I’ve had a NIAC grant and its never assumed anything is glibly”” doable. NIAC grants are speculative by definition.”””

    Reply
  58. Just got to love the physics. First… we fill up a ship full of deuterium-tritium-uranium targets. Then… we feed them at 100 Hz into each blast chamber Then… we blast each with a 2,000,000 amp, 2,000,000 volt pulse Which… explodes the little cores. Fission, Fusion, ejecta. Then… that’s captured by the magnetic nozzle, which Deflects… the particles making thrust And… makes a pulse of current, recharging the capacitors. To… start it all over again. MAKING… sufficient thrust to “do the Kessel Run in less than 3 parsecs”. Ahem… the Earth↔Mars run in 37 days. The ISP is to be 90,000, reaction-mass velocity of 9.81× that. 883 km/s. The rocket weighs how much again? Well … wasn’t stated. But let’s guess (starts a spreadsheet, goes away for awhile…) OK, back. If fuel is 16.7% of the ship mass, If 27% fuel-use-up is performed to accelerate out to Mars, If 25.8% fuel-use-up is used to decelerate If ISP is 90,000 (883 km/s) If 30,000 kg is the ship mass incl. fuel at launch If acceleration is concentrated in first 10% of trip (3.7 days) If deceleration is ocncentrated in last 9.5% of trip THEN the ship will attain a speed of 40.6 km/s Which when drifting for 29.8 days… Goes about 0.78 AU. And there you are!!! _______ Only remaining details are solveable by intrepid post-Grad students. Little things like how fast a burn rate (4.2 g/sec), exhaust energy 1.6 gigawatts, whether enough ²³⁵U could fission (4.1%), amount of waste heat — radiant and impact-from-neutrons heat, 90% or 1,300,000,000 W to contend with on the nozzle-end of things. Just saying, goats. By no means as glibly doable as is let on to be. Just saying, [b]Goat[/b]Guy

    Reply
  59. Just got to love the physics. First… we fill up a ship full of deuterium-tritium-uranium targets. Then… we feed them at 100 Hz into each blast chamberThen… we blast each with a 2000000 amp 2000000 volt pulseWhich… explodes the little cores. Fission Fusion ejecta.Then… that’s captured by the magnetic nozzle whichDeflects… the particles making thrustAnd… makes a pulse of current recharging the capacitors.To… start it all over again. MAKING… sufficient thrust to do the Kessel Run in less than 3 parsecs””. Ahem… the Earth↔Mars run in 37 days. The ISP is to be 90″”0 reaction-mass velocity of 9.81× that. 883 km/s.The rocket weighs how much again? Well … wasn’t stated. But let’s guess (starts a spreadsheet goes away for awhile…)OK back.If fuel is 16.7{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of the ship mass If 27{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} fuel-use-up is performed to accelerate out to MarsIf 25.8{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} fuel-use-up is used to decelerateIf ISP is 90000 (883 km/s)If 30000 kg is the ship mass incl. fuel at launchIf acceleration is concentrated in first 10{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of trip (3.7 days)If deceleration is ocncentrated in last 9.5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of tripTHEN the ship will attain a speed of 40.6 km/sWhich when drifting for 29.8 days… Goes about 0.78 AU. And there you are!!!_______Only remaining details are solveable by intrepid post-Grad students. Little things like how fast a burn rate (4.2 g/sec) exhaust energy 1.6 gigawatts whether enough ²³⁵U could fission (4.1{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12}) amount of waste heat — radiant and impact-from-neutrons heat 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} or 13000000 W to con”

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  60. By the way, it’s been obvious for a long, long time that you could do this, the obstacle is really regulatory, not so much technology.

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  61. By the way it’s been obvious for a long long time that you could do this the obstacle is really regulatory not so much technology.

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  62. If you’ve got a propulsion system like that, you’d be far better off reaching Mars in 7 months with an enormously larger payload. Because you could carry enough payload to provide more than adequate radiation shielding for the crew.

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  63. If you’ve got a propulsion system like that you’d be far better off reaching Mars in 7 months with an enormously larger payload. Because you could carry enough payload to provide more than adequate radiation shielding for the crew.

    Reply
  64. On a side note, you can make sense of the movie line, if you just understand him to be bragging about taking some shortcuts anybody else would view as insanely dangerous. “I went straight through it!” Through, realistically, somebody just thought a parsec was a unit of time, it can be fun trying to rationalize movie mistakes.

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  65. Sure the various fusion projects all HOPE to achieve net positive fusion. But as yet the only proven ways to achieve this is via a fission trigger (ie. a Hydrogen bomb) or by having a mass the size of a star.

    Reply
  66. Exactly right. However, using another astrophysics model (not our sun) in this case pulsars and neutron stars, the temperature for boron proton fusion seems to have been consistently, repeatably, achieved :

    ( from: (PDF) Fusion reactions from >150 keV ions in a dense plasma focus. plasmoid.https://www.researchgate.net/publication/236221996_Fusion_reactions_from_150_keV_ions_in_a_dense_plasma_focus_plasmoid)

    “Using a dense plasma focus device with a 50 kJ capacitor charge, we have observed fusion reactions from deuterium ions with record energies of >150 keV, which are confined for durations of 7–30 ns in the cores of plasmoids with typical radii of 300–500 μm and densities ∼3 × 1019 cm−3. We have for the first time simultaneously imaged the plasmoid at high (30 μm) resolution and measured trapped ion energy and neutron anisotropy. The isotropy of the neutron emission as well as other observations confirms that the observed neutrons per pulse of up to 1.5 × 1011 are produced mainly by confined ions, not an unconfined beam. The conditions achieved are of interest for aneutronic fusion, such as with pB11 fuel. ”

    and then from: https://lppfusion.com/space-propulsion/

    ” In space, Focus Fusion could provide not just power, but propulsion as well. Focus Fusion generates a beam of ions that accelerates rapidly away from the central anode, and by rapidly we mean at around a thousand kilometers per second! That works out to around one million seconds of specific impulse, a measure of rocket engine efficiency. So every Focus Fusion generator also happens to be an ultra-efficient rocket. …

    If more thrust is desired, Focus Fusion’s power output could be modified or combined with power-hungry propulsion systems such as……..”

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  67. The whole point (though never explicitly stated that I can see) is that it is thought/hoped to be much easier to get the fission-fusion reaction to start than a pure fusion. So much easier that it is possible to ignite the reactions without needing a laser system the size of a town.

    Given that people have been trying to get fusion to work (at a scale where energy out> energy in) for over half a century, it may well be that it would be insisting on pure fusion that would make sure the concept never gets anywhere.

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  68. And, as with the Kessel Run, it is possible to measure the speed of the run by measuring the travel DISTANCE.

    The more effective your space drive, the shorter your travel distance. A continuous 6g acceleration is just about a straight line when the two planets are in conjunction. The really slow ships have to spiral out over half an orbit or more.

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  69. RadicalModerate one time did an ideal gas calc with uranium at giga-pascals of pressure and argued that the density of the uranium could be made hundreds of grams per cc and that this could, you know, do what they are saying here (blow up).

    Well, if that works and we can fission a hundred milligrams at a time then space travel is on. So, what has been obvious for a long time? That ultra condensed matter physics makes sub gram bombs possible? I’ve been following Z-machine since the early 2000s. News out of there is pretty scarce – it’s been a letdown like NIF. Yet another possibility limited by lack of ability to deliver 50MJ in a nanosecond.

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  70. The biosphere doesn’t typically care about levels of radioactive pollution that humans could achieve over significant areas without resorting to large numbers of cobalt clad neutron bombs. The biosphere wouldn’t even notice this being used in near Earth space.

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  71. Just got to love the physics.

    First… we fill up a ship full of deuterium-tritium-uranium targets.
    Then… we feed them at 100 Hz into each blast chamber
    Then… we blast each with a 2,000,000 amp, 2,000,000 volt pulse
    Which… explodes the little cores. Fission, Fusion, ejecta.
    Then… that’s captured by the magnetic nozzle, which
    Deflects… the particles making thrust
    And… makes a pulse of current, recharging the capacitors.
    To… start it all over again.

    MAKING… sufficient thrust to “do the Kessel Run in less than 3 parsecs”.
    Ahem… the Earth↔Mars run in 37 days.

    The ISP is to be 90,000, reaction-mass velocity of 9.81× that. 883 km/s.
    The rocket weighs how much again? Well … wasn’t stated.
    But let’s guess (starts a spreadsheet, goes away for awhile…)

    OK, back.
    If fuel is 16.7% of the ship mass,
    If 27% fuel-use-up is performed to accelerate out to Mars,
    If 25.8% fuel-use-up is used to decelerate
    If ISP is 90,000 (883 km/s)
    If 30,000 kg is the ship mass incl. fuel at launch
    If acceleration is concentrated in first 10% of trip (3.7 days)
    If deceleration is ocncentrated in last 9.5% of trip

    THEN the ship will attain a speed of 40.6 km/s
    Which when drifting for 29.8 days…
    Goes about 0.78 AU.

    And there you are!!!
    _______

    Only remaining details are solveable by intrepid post-Grad students. Little things like how fast a burn rate (4.2 g/sec), exhaust energy 1.6 gigawatts, whether enough ²³⁵U could fission (4.1%), amount of waste heat — radiant and impact-from-neutrons heat, 90% or 1,300,000,000 W to contend with on the nozzle-end of things.

    Just saying, goats.
    By no means as glibly doable as is let on to be.

    Just saying,
    [b]Goat[/b]Guy

    Reply
  72. If you’ve got a propulsion system like that, you’d be far better off reaching Mars in 7 months with an enormously larger payload. Because you could carry enough payload to provide more than adequate radiation shielding for the crew.

    Reply

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