WEBVTT 1 00:00:04.040 --> 00:00:05.610 Richard D'Arcy: Let me share my screen. 2 00:00:06.530 --> 00:00:08.220 Richard D'Arcy: Can everyone see that. 3 00:00:08.540 --> 00:00:09.220 Stefania Juks: Great. 4 00:00:09.760 --> 00:00:11.049 Richard D'Arcy: And in full screen. 5 00:00:11.840 --> 00:00:13.280 Stefania Juks: Yeah, that's much better. Thank you. 6 00:00:13.430 --> 00:00:13.815 Richard D'Arcy: Great. 7 00:00:14.430 --> 00:00:35.490 Richard D'Arcy: Yeah. So good afternoon. Everyone. Thank you for the organizers for the opportunity to speak today. A few talks ago Benno very eloquently outlines some of the thoughts that gone into the sustainability efforts for other linear collider schemes that are far more advanced than what I'm going to talk about today, such as the Ilc 8 00:00:36.097 --> 00:00:43.030 Richard D'Arcy: And what I am going to talk about today is is a new concept that's only really been around for the last couple of years. 9 00:00:43.410 --> 00:00:52.929 Richard D'Arcy: which implements plasma accelerated technology in the hope that it can make a linear collider smaller, cheaper, but also potentially greener. 10 00:00:53.390 --> 00:00:58.790 Richard D'Arcy: And that's hopefully what I'm going to focus on today and convince you that this could be the case. 11 00:01:00.490 --> 00:01:12.160 Richard D'Arcy: Okay? So a brief bit of background on particle physics, and how plasmas could fit in. So we really are at a critical time for particle physics. We need to plan for the post. Lhc. Era 12 00:01:12.460 --> 00:01:28.950 Richard D'Arcy: fccee will be fantastic. I'm sure that that will be the outcome of the esppu process, that everyone's very excited about that. But it is extremely expensive. Linear colliders, such as Irc and click promise a reduced cost. 13 00:01:29.130 --> 00:01:35.430 Richard D'Arcy: at least for some some part of physics space. But they're still very expensive. 14 00:01:36.010 --> 00:01:44.119 Richard D'Arcy: and the key cost driver really, colliders is the accelerating gradient, which is limited to something like 100 megavolts per meter, often operating much lower than this. 15 00:01:44.390 --> 00:01:52.620 Richard D'Arcy: however, plasma, acceleration promises much higher gradients, so something like potentially 3 orders of magnitude higher, but at least one order of magnitude higher. 16 00:01:53.490 --> 00:02:12.620 Richard D'Arcy: But when you're thinking about just the gradient, this sounds absolutely brilliant. You could reduce the cost of the facility by a factor of 1,000 as well. But that's actually not the only cost driver. And importantly, as I'll explain, it's maybe not even the most important one. So you have to consider what are the cost drivers that define the design choices of plasma accelerators. 17 00:02:13.000 --> 00:02:23.340 Richard D'Arcy: and I should point out that half is not new in terms of its idea. There have been several plasma based collider designs proposed for the last 30 years. 18 00:02:23.680 --> 00:02:25.899 Richard D'Arcy: And here's an example of one here on the bottom right? 19 00:02:26.290 --> 00:02:30.600 Richard D'Arcy: And typically, they represent the state of the field at the time. 20 00:02:30.940 --> 00:02:40.929 Richard D'Arcy: So they're useful for identifying the remaining challenges for focusing down where the field needs to go. For example, where we are conceptually and where we need to be experimentally. 21 00:02:42.040 --> 00:02:46.879 Richard D'Arcy: So, plasma accelerators is a developing technology. It's certainly not ready 22 00:02:47.120 --> 00:02:51.639 Richard D'Arcy: for for applications of particle physics. Certainly not high energy physics. 23 00:02:51.770 --> 00:02:57.510 Richard D'Arcy: But we're not far away. A lot of important results have come out in the last decade or so 24 00:02:57.740 --> 00:03:12.399 Richard D'Arcy: we are maturing towards real life applications, for example, strong Field, Qed. Some experiments were performed in 2018, which showed that you can actually perform this strong field. Qed. Experiments by colliding a laser beam with an accelerated 25 00:03:12.430 --> 00:03:40.070 Richard D'Arcy: electron beam which is accelerated in a laser weight of accelerator, but also free electron lasing, which has a lot of the same problems and challenges as a collider. But just on a smaller scale. So if we can demonstrate free electron lasing, then it really is a motivator for the field. And these are some results that came out only a couple of years ago, most published in nature. And there are 6 key aspects of research that are relevant to colliders. And they're all tied up loosely in the equation for luminosity. 26 00:03:40.180 --> 00:03:59.299 Richard D'Arcy: So we need high energy transfer efficiency, high repetition rate and average power. We need to preserve the high beam quality for the interaction point for focusing, and also need to stage to very high energy. And the whole thing needs to be very stable. But there's also one outstanding challenge in our field which is highlighted here in red, which I'll talk about in a bit 27 00:03:59.470 --> 00:04:07.660 Richard D'Arcy: positron acceleration. But what I wanted to just briefly touch on 1st was energy transfer efficiency because it has some relevance to sustainability. 28 00:04:08.790 --> 00:04:20.129 Richard D'Arcy: So energy transfer efficiency in the plasma accelerations can in principle be extremely high, can be something like 80% from main beam to accelerated beam. 29 00:04:20.329 --> 00:04:41.850 Richard D'Arcy: and this is due to the fact that we can heavily beam, load the electric fields in a plasma accelerator, and we can get away with this, whereas you can't really in more traditional radio frequency cavities, because the quality factor of these plasma wakes is effectively one. We perturb this plasma we generate a single accelerated cavity, and it very quickly damps. 30 00:04:42.060 --> 00:04:45.000 Richard D'Arcy: So we have to do all our acceleration in this one cavity. 31 00:04:45.320 --> 00:04:49.929 Richard D'Arcy: but that means that we can essentially do whatever we want to this cavity, we can perturb it in whatever we want. 32 00:04:50.270 --> 00:04:57.340 Richard D'Arcy: and we can see here that you can heavily deem load this and flatten out the electric fields. And this means that you can get uniform acceleration across the entire bunch. 33 00:04:57.440 --> 00:05:03.409 Richard D'Arcy: And because of this we can get something like a factor of 4. Increase in energy transfer efficiency 34 00:05:04.052 --> 00:05:07.069 Richard D'Arcy: over competitive schemes such as click. 35 00:05:07.440 --> 00:05:11.290 Richard D'Arcy: And there has been a lot of research in this direction in the last few years. 36 00:05:11.420 --> 00:05:28.609 Richard D'Arcy: And so, for example, if you break this down, you have to transfer energy from the drive beam to the wake field, and then from the wake field to the witness beam. The accelerating beam and proof of principle results have shown you can get 60% from the dry beam to the wake, and then you can extract 40% of that energy 37 00:05:28.730 --> 00:05:30.569 Richard D'Arcy: from the weight of the accelerating beam. 38 00:05:31.030 --> 00:05:45.069 Richard D'Arcy: and that gives a 20% beam to beam transfer which is comparable with the number that I mentioned from Click. But it's still some far way away from the 80%. That's theoretically possible. So there is more progress to be made in this area. 39 00:05:45.500 --> 00:06:00.009 Richard D'Arcy: But, as I mentioned earlier, for all the benefits, such as energy, transfer, efficiency and the progress therein. Positron acceleration lags significantly behind, with something like maybe a decade or 2 behind the progress that's been made for electron acceleration in plasma. 40 00:06:00.120 --> 00:06:02.940 Richard D'Arcy: And the main challenge here is that electron motion 41 00:06:03.507 --> 00:06:09.070 Richard D'Arcy: which is essentially equivalent to ion motion for the positrons. But plasma electrons are much lighter. 42 00:06:09.780 --> 00:06:16.429 Richard D'Arcy: I should point out that there have been some experimental results in positrons. So, for example. 43 00:06:16.610 --> 00:06:27.349 Richard D'Arcy: this is a result that was published in nature about a decade ago, and they use the positron beam to drive a wake field and also accelerate parts of positron beam towards the tail. 44 00:06:28.000 --> 00:06:43.610 Richard D'Arcy: So it has been experimentally demonstrated. But even if it were optimized very rapidly over the next few years, there would still be an issue which is the luminosity of power is orders of magnitude below radio frequency and electron positron acceleration. 45 00:06:45.540 --> 00:06:46.630 Richard D'Arcy: So 46 00:06:46.910 --> 00:06:52.739 Richard D'Arcy: if we were to build a collider in this regard, we'd have a problem which is positron acceleration and plasma. 47 00:06:53.040 --> 00:07:00.679 Richard D'Arcy: So we had a pragmatic idea which was to accelerate the electrons to very high energy in plasma. 48 00:07:01.350 --> 00:07:06.159 Richard D'Arcy: But then use radio frequency technology to accelerate positrons. 49 00:07:06.370 --> 00:07:19.330 Richard D'Arcy: But if you did this, and you had it as a an even center of mass, so symmetric energies. Then the footprint would be dwarfed by the Rf. For the positrons, so the idea was, can we make it asymmetric? 50 00:07:20.000 --> 00:07:27.319 Richard D'Arcy: And essentially, if we go up in energy, let's just say arbitrarily, 4 times higher in electron 4 times lower in positrons. 51 00:07:27.900 --> 00:07:31.920 Richard D'Arcy: and you can make this whole thing more compact, but you make it less energy efficient. 52 00:07:32.560 --> 00:07:40.539 Richard D'Arcy: So to improve the energy efficiency. You have less charge at high energy in the electrons and more charge in the positron bunch. 53 00:07:41.280 --> 00:07:44.699 Richard D'Arcy: And then it turns out if you can make the admittances 54 00:07:45.340 --> 00:08:02.160 Richard D'Arcy: different. So asymmetric due to the Beta functions being therefore different at the interaction point, you can then improve tolerances for plasma accelerators, and this is how we've essentially progressed from what is effectively the Ilc towards half. 55 00:08:03.510 --> 00:08:11.709 Richard D'Arcy: So we want to design harp. We want to do it properly and rigorously, and this sends us back to the drawing board. How do we actually improve a particle collider? 56 00:08:11.850 --> 00:08:21.700 Richard D'Arcy: And I mentioned it earlier? It goes just beyond the accelerated radius you have to optimize for the power source, the accelerator, the energy uses, and also importantly, put carbon tax on all of this. 57 00:08:22.050 --> 00:08:36.809 Richard D'Arcy: and you need to optimize this whole thing for cost. And I won't go into too much detail. This is just really for posterity. But essentially, you can start looking at things like the optimizing the beam power from the source to the, to the beam itself. 58 00:08:37.130 --> 00:08:53.479 Richard D'Arcy: But you have to then also consider what the best type of driver technology is to reduce the cost of power delivered from that source. So once you factor in all these things, you have the benefits of plasma, but also the potential downsides of plasma. So you have to find a balance between how this could all look 59 00:08:53.830 --> 00:09:07.129 Richard D'Arcy: in a cost of optimization scheme. And this is effectively what we did. We put together a detailed physics and cost model. So we put lots of inputs that we could get from more advanced 60 00:09:07.700 --> 00:09:13.930 Richard D'Arcy: design, such as that as in click. And then we optimized all of this with Bayesian based machine learning. 61 00:09:14.400 --> 00:09:18.649 Richard D'Arcy: And this is essentially the footprint that is spat out. 62 00:09:18.880 --> 00:09:24.910 Richard D'Arcy: So you can see here we have this driver, Linux, which is then being combined 63 00:09:25.120 --> 00:09:31.710 Richard D'Arcy: the bunches, and then sentence this plasma accelerator, which then takes the bunches from something like 64 00:09:32.160 --> 00:09:54.090 Richard D'Arcy: 4 gev. Up to 380 gev. And then we use some of those beams to generate the positron target. These positrons are then sent all the way around here, pointing to a damping ring, put through a cool copper linac, and then sent together into this beam delivery system to this interaction point here to produce 250 Gev. Sensor of mesh. 65 00:09:54.210 --> 00:10:01.600 Richard D'Arcy: and it starts looking very similar in some regards to existing design. So, for example, you end up with something like a click like drive beam. 66 00:10:02.350 --> 00:10:13.420 Richard D'Arcy: And that makes sense because the plasma is essentially just a transformer. It's transforming low energy. High current beams into high energy, low current beams. 67 00:10:13.670 --> 00:10:42.160 Richard D'Arcy: And importantly, we have a plasma line here which has 48 stages and 10 megawatts of heating. So these are outstanding challenges. I'll touch on these a little bit later, and we chose semi-conservative energy transfer efficiency. So 40% beam to beam. So a factor of 2 higher than what's been shown experimentally, but still a factor of 2 below the theoretical value. And if you're interested in more details, this can be found in the submission that we put forward for the Esppe process recently. 68 00:10:43.440 --> 00:10:46.730 Richard D'Arcy: So importantly, this has a length of 5 kilometers 69 00:10:47.110 --> 00:10:52.360 Richard D'Arcy: and a cost of something like 3.4 billion dollars in 2024 money. 70 00:10:53.390 --> 00:10:57.710 Richard D'Arcy: The emissions here are given in terms of construction and run costs. 71 00:10:58.300 --> 00:11:08.280 Richard D'Arcy: and the water is approximately 106 megawatts, and this is all assuming a 10 year period of operation, producing an integrated to inverse atoms. 72 00:11:09.270 --> 00:11:33.260 Richard D'Arcy: But, importantly, if you can compare these numbers to other collid designs, such as irc and click. You can see here that the the length is approximately 25% of the irc. The cost is something similar, and the emissions come from construction are some, a percentage that's similar. And the same goes for click. It's something like 50%, the length and cost and emissions of click. 73 00:11:33.260 --> 00:11:52.519 Richard D'Arcy: So something that's interesting that's come out of this is that the emissions, the carbon emissions from construction approximately scale with the length of the cost, and this makes sense given recent studies that have shown that a lot of the Co. 2 that's produced during the build is the concrete, for example, that's required for the tunnels 74 00:11:52.830 --> 00:12:03.329 Richard D'Arcy: and the wall. Plug power here, I should say, is, is very similar to Ilc and Click. But this doesn't take account for the fact that we could potentially push the energy transfer efficiency even further in the future. 75 00:12:04.700 --> 00:12:11.619 Richard D'Arcy: Okay, so I won't touch too much on this slide. This is really just to highlight what the 2 major outstanding challenges are between 76 00:12:11.920 --> 00:12:20.769 Richard D'Arcy: where we are now and and building half, and they are essentially staging of plasma sources. We need to get to very high energy. We need 48 of these plasma stages for half. 77 00:12:21.470 --> 00:12:24.910 Richard D'Arcy: and the current state of the art is 2 stages. 78 00:12:25.050 --> 00:12:37.969 Richard D'Arcy: and that's only in a proof of principle way. And if we are going to go to very high luminosity, then we need a very high rep rate, and that requires much more average power in these plasma sources than we've ever had before. Orders of magnitude, in fact. 79 00:12:38.100 --> 00:12:52.829 Richard D'Arcy: So we're going to need something that can handle multi Kev plasma temperatures. And that's just from a single bunch. This could be hundreds of Kev temperatures across a full bunch strain, which is approximately the temperature of the sun. 80 00:12:53.030 --> 00:13:00.450 Richard D'Arcy: And we need to cool these. So we need much higher cooling rates than what are designed for for click. 81 00:13:00.650 --> 00:13:07.609 Richard D'Arcy: Well, because we have this tangible design, it means that we can consider new optimizations, especially for sustainability. 82 00:13:07.880 --> 00:13:35.889 Richard D'Arcy: And one idea that we really just had only a week ago or so sketched out on the back of an envelope which I'll just very briefly talk about now is, can we essentially use this high temperature to do something? Can it give something back for us which couldn't be possible, for example, with a superconducting Rf. Line because it's cold. So if you take the half example, you've got 23 megawatts of power going into this driving, and only about 10 megawatts make it to the accelerating beam. 83 00:13:36.550 --> 00:13:48.610 Richard D'Arcy: And then, of all of that energy essentially 20 megawatts is lost in the Rf. So you could potentially put a water cooling loop in. Amongst all of this 84 00:13:48.860 --> 00:13:54.269 Richard D'Arcy: heat the cool water from cool to Lukewar with the Rf. Inac. 85 00:13:54.400 --> 00:13:59.419 Richard D'Arcy: Then part of the energy in these drive beams is lost in the dumps. 86 00:13:59.550 --> 00:14:17.959 Richard D'Arcy: You could then take that loop warm and make it warm, and then you could put it through the extremely hot plasma cells. So on the previous slide I showed a scheme for a cryo cooled plasma source. This may be what's required. But if we could get away with water that you could cool with water, and then take what's lost in the plasma 87 00:14:18.060 --> 00:14:39.079 Richard D'Arcy: and turn into very hot steam. And if you just think back at the envelope, calculations assuming the costs for the ventilation of cooling that we scale from click, and also very rough estimates of how much it would cost to operate a steam turbine, how much they would be efficient. You get a very rough idea of how you could go through this scheme. 88 00:14:39.140 --> 00:14:59.420 Richard D'Arcy: and I won't go through the numbers. I'll leave them on the slides online, so you can take a look at them in more detail, but potentially you can generate something or save something like 5 to 15 megawatts of power. This saves something like 10 to 40 megawatts upfront in these ventilation and cooling costs, and that then saves you something like 5 to 15 million dollars per year in the electricity bill. 89 00:14:59.610 --> 00:15:07.619 Richard D'Arcy: And this is just the heart. If you want to go to a 10 TV collider, which is one of the goals in the Us. You could be looking at 100 million per year. 90 00:15:07.920 --> 00:15:10.110 Richard D'Arcy: And this is only possible with hot technology. 91 00:15:10.580 --> 00:15:18.859 Richard D'Arcy: So to conclude, plasma has the potential to increase sustainability, to have many ways, the obvious ways are the build cost and the operation cost 92 00:15:19.611 --> 00:15:23.430 Richard D'Arcy: and half represents the most tangible design in this regard. 93 00:15:24.860 --> 00:15:36.510 Richard D'Arcy: but the tangibility means that we can start thinking about real world problems and producing real world solutions, such as, for example, using the plasma heating to return some energy back to the system. 94 00:15:36.770 --> 00:15:42.300 Richard D'Arcy: And we're likely only scratching the surface of the sustainability benefits of plasma accelerators. Thank you. 95 00:15:45.430 --> 00:15:47.899 Stefania Juks: Thank you so much, Richard, for a very interesting talk. 96 00:15:49.210 --> 00:15:51.450 Stefania Juks: and we are ready for any questions. 97 00:15:52.340 --> 00:15:53.700 Stefania Juks: Join, please. 98 00:15:55.656 --> 00:16:05.050 Dwayne Spiteri: Thank you, Richard. This is actually fantastic talk. The slides where you had the changes from Irc to to have the 99 00:16:05.840 --> 00:16:15.780 Dwayne Spiteri: yeah, this one. This is very nice one. Can you explain to me again why you want to go for the asymmetric energies, to charges, to emittances like, what does that do in terms of sustainability? 100 00:16:17.030 --> 00:16:18.160 Richard D'Arcy: And so 101 00:16:18.580 --> 00:16:39.020 Richard D'Arcy: from the point of sustainability, it doesn't do too much. So it doesn't necessarily save you in power, for example. So one of the problems of going from in energy, from symmetric to asymmetric energy, is that you actually then make this whole thing less energy efficient. And we could have just left it. At that. We could have just said right. 102 00:16:39.190 --> 00:16:48.449 Richard D'Arcy: We'll leave it as it is, same charges, different energies, and we'll just take a hit in the power. But then, really, the asymmetric charge was to 103 00:16:48.560 --> 00:17:03.149 Richard D'Arcy: deal with that from a sustainability point of view, we didn't want to come in saying that we don't care about how much this thing is gonna produce like in terms of Co 2. So I guess the answer is really that we've considered this. And we've tried to just make it as stable as possible with regards to Irc. 104 00:17:03.966 --> 00:17:14.399 Richard D'Arcy: So sustainability wise. It works out similar in terms of how this thing for all runs, but really it's much cheaper and lower the carbon tax to to build this thing. 105 00:17:17.970 --> 00:17:18.949 Dwayne Spiteri: Keep me wrong, sir. 106 00:17:23.130 --> 00:17:25.570 Stefania Juks: And there is one more question from Chandra Moli. 107 00:17:26.907 --> 00:17:32.459 Chandramauli: Hi! I might have missed it. But what's the current status of the project? 108 00:17:34.300 --> 00:17:42.330 Richard D'Arcy: So, we are developing a Pre. Cvr. So we've published a 10 page submission to the Esppu 109 00:17:43.255 --> 00:17:47.810 Richard D'Arcy: that's online. There's a link in the slides to archive. 110 00:17:48.420 --> 00:17:49.280 Richard D'Arcy: And 111 00:17:49.540 --> 00:18:07.769 Richard D'Arcy: we've made progress essentially in individual elements of R&D for this for this project essentially subsystems. But they've kind of operated in a siloed way. So far we've put together this, which is Bayes and optimized, but it takes a lot of a lot of leaps of faith. 112 00:18:07.910 --> 00:18:23.359 Richard D'Arcy: So the next step over the next year is to take what we've done for the Espdu and turn it into a cradle to grave simulation which covers the entire concept and then publish that in a Pre. Cdr. And then from there a Cdr. And a Tdr. Over the next 3 to 5 years. 113 00:18:31.510 --> 00:18:36.929 Stefania Juks: Well, I hope that sort of answers the question thanks a lot, Richard. This was a very interesting talk. 114 00:18:37.736 --> 00:18:44.699 Stefania Juks: I think we can move on to the last one of the day. If I'm not wrong. Hopefully, I'm not wrong.