Optical Modeling for a Laser Phased-Array Directed Energy System

We present results of optical simulations for a laser phased array directed energy system. The laser array consists of individual optical elements in a square or hexagonal array. In a multi-element array, the far-field beam pattern depends on both mechanical pointing stability and on phase relationships between individual elements. The simulation incorporates realistic pointing and phase errors. Pointing error components include systematic offsets to simulate manufacturing and assembly variations. Pointing also includes time-varying errors that simulate structural vibrations, informed from random vibration analysis of the mechanical design. Phase errors include systematic offsets, and time-varying errors due to both mechanical vibration and temperature variation in the fibers. The optical simulation is used to determine beam pattern and pointing jitter over a range of composite error inputs. Results are also presented for a 1 m aperture array with 10 kW total power, designed as a stand-off system on a dedicated asteroid diversion/capture mission that seeks to evaporate the surface of the target at a distance of beyond 10 km. Phase stability across the array of λ/10 is shown to provide beam control that is sufficient to vaporize the surface of a target at 10 km. The model is also a useful tool for characterizing performance for phase controller design in relation to beam formation and pointing

Directed Energy Deflection Laboratory Measurements

We report on laboratory studies of the effectiveness of directed energy planetary defense as a part of the DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) program. DE-STAR and DE-STARLITE are directed energy stand-off and stand-on programs, respectively. These systems consist of a modular array of kilowatt-class lasers powered by photovoltaics, and are capable of heating a spot on the surface of an asteroid to the point of vaporization. Mass ejection, as a plume of evaporated material, creates a reactionary thrust capable of diverting the asteroid’s orbit. In a series of papers, we have developed a theoretical basis and described numerical simulations for determining the thrust produced by material evaporating from the surface of an asteroid. In the DE-STAR concept, the asteroid itself is used as the deflection propellant . This study presents results of experiments designed to measure the thrust created by evaporation from a laser directed energy spot. We constructed a vacuum chamber to simulate space conditions, and installed a torsion balance that holds an asteroid sample. The sample is illuminated with a fiber array laser with flux levels up to 60 MW/m2 which allows us to simulate a mission level flux but on a small scale. We use a separate laser as well as a position sensitive centroid detector to readout the angular motion of the torsion balance and can thus determine the thrust. We compare the measured thrust to the models. Our theoretical models indicate a coupling coefficient well in excess of 100 μN/W optical, though we assume a more conservative value of 80 μN/W optical and then degrade this with an optical encircled energy efficiency of 0.75 to 60 μN/W optical in our deflection modeling. Our measurements discussed here yield about 45 μN/W absorbed as a reasonable lower limit to the thrust per optical watt absorbed

Local phase control for a planar array of fiber laser amplifiers

Arrays of phase-locked lasers have been developed for numerous directed-energy applications. Phased-array designs are capable of producing higher beam intensity than similar sized multi-beam emitters, and also allow beam steering and beam profile manipulation. In phased-array designs, individual emitter phases must be controllable, based on suitable feedback. Most current control schemes sample individual emitter phases, such as with an array-wide beam splitter, and compare to a master phase reference. Reliance on a global beam splitter limits scalability to larger array sizes due to lack of design modularity. This paper describes a conceptual design and control scheme that relies only on feedback from the array structure itself. A modular and scalable geometry is based on individual hexagonal frames for each emitter; each frame cell consists of a conventional lens mounted in front of the fiber tip. A rigid phase tap structure physically connects two adjacent emitter frame cells. A target sensor is mounted on top of the phase tap, representing the local alignment datum. Optical sensors measure the relative position of the phase tap and target sensor. The tap senses the exit phase of both emitters relative to the target normal plane, providing information to the phase controller for each emitter. As elements are added to the array, relative local position data between adjacent phase taps allows accurate prediction of the relative global position of emitters across the array, providing additional constraints to the phase controllers. The approach is scalable for target distance and number of emitters without loss of control

Taloyhtiöistä tulevaisuuden energiatuottajia – Muutospolut vuoteen 2035 ja murrosareena tiedon yhteistuotannon menetelmänä

Noin neljännes Suomen asuntokannasta koostuu taloyhtiöistä. Niistä merkittävä osa tarvitsee lähivuosina korjauksia, joiden avulla voidaan kehittää rakennuskannassa tapahtuvaa hajautettua energiantuotantoa esimerkiksi aurinkopaneelien ja lämpöpumppuratkaisujen avulla. Vuonna 2018 voimaan tullut EU:n energiayhteisösääntely luo yhdessään meneillään olevat kansallisten sääntelymuutosten kanssa perustan, jonka varassa taloyhtiöt voivat vahvistaa kansalaisten energiantuottajaroolia tulevaisuudessa. Murros taloyhtiöiden kestävään energiantuotantoon on haaste, joka edellyttää useiden yhteiskunnan osa-alueiden näkökulmien ja toimijoiden kokoamista yhteen. Tätä tavoitetta varten järjestettiin vuonna 2020 Kansalaisenergia-areena – tiedon yhteistuotannon kokeilu, jonka vaiheita ja johtopäätöksiä kuvataan käsillä olevassa raportissa. Raportissa hahmotellaan haasteita ja mahdollisuuksia, joita liittyy taloyhtiöiden muuntautumiseen passiivisista energian kuluttajista aktiivisiksi energian tuottajiksi ja muuttuvan energiajärjestelmän toimijoiksi. Keskiössä ovat neljä murrospolkua, joissa on jäsennetty erilaisia toimenpiteitä murroksen käynnistämiseksi. Samalla työ tarjoaa seikkaperäisen kuvauksen murrosareenamenetelmän päävaiheista tulevaa käyttöä ja kehittämistä varten. Areenatyön tulokset osoittavat, että toimenpiteitä tarvitaan useilla alueilla. Ensinnäkin luotettava tieto on koostettava selkeästi tavoitettavaan muotoon, jossa se on eri toimijoiden käytettävissä. Nykyisin yleistä tietoa ja esimerkkitapausten kuvauksia on tarjolla runsaasti, mutta niiden vertailu ja soveltaminen on äärimmäisen vaikeaa. Toiseksi taloyhtiöt tarvitsevat parempia kanavia vertaisoppimiselle ja kohdennetulle neuvonnalle. Tärkeimpinä keinoina tunnistettiin julkisen energianeuvonnan jalkauttaminen lähemmäs taloyhtiöitä sekä vertaisoppimisen ja yhteistyön tilojen, kuten kortteliklubien ja edelläkävijäverkostojen kehitys. Kolmanneksi markkinoille tarvitaan voimakkaampia signaaleja palvelutarjonnan kehitykselle ja uudenlaisten kokonaisratkaisujen kehitykselle. Valtion energia-avustuksen jatko voi olla keino ennakoitavalle ja jatkuvalle ohjaukselle. Lisäksi vaaditaan poliittista tahtoa ja strategista näkemystä, jotta kansalaisenergian kehittämiselle on olemassa resursseja myös tulevaisuudessa. Politiikkakehityksen kannalta olennaista onkin monien samanaikaisesti etenevien muutosten yhteiskunnallinen koordinaatio. Toimenpiteitä tarvitaan niin taloyhtiöiden tasolla, jolla hankkeet toteutetaan, politiikan tasolla, jolla luodaan ennakoitavaa tulevaisuusnäkymää, sekä tiedon hallinnan tasolla, joka toimii kahta muuta yhteen nivovana ulottuvuutena. Taloyhtiöiden kansalaisenergiantuotannossa ei olekaan kyse yksittäisestä murroksesta, jolla olisi selkeä omistaja, vaan hajanaisten toimenpiteiden keskinäisistä suhteista, mikä korostaa politiikkasektorien välisen vuoropuhelun merkitystä. Raportissa esitellään myös noin 30 toimenpidettä eri toimijoille, jotka havainnollistavat minkälaisin keinoin taloyhtiöiden energiaroolia voidaan muuttaa. Jatkossa on tärkeää jatkaa dialogia eri toimijoiden kesken sekä käynnistää kokeiluja etenkin tiedon hallintaan ja taloyhtiöiden räätälöityyn tukeen liittyen

Directed energy missions for planetary defense

Directed energy for planetary defense is now a viable option and is superior in many ways to other proposed technologies, being able to defend the Earth against all known threats. This paper presents basic ideas behind a directed energy planetary defense system that utilizes laser ablation of an asteroid to impart a deflecting force on the target. A conceptual philosophy called DE-STAR, which stands for Directed Energy System for Targeting of Asteroids and exploration, is an orbiting stand-off system, which has been described in other papers. This paper describes a smaller, stand-on system known as DE-STARLITE as a reduced-scale version of DE-STAR. Both share the same basic heritage of a directed energy array that heats the surface of the target to the point of high surface vapor pressure that causes significant mass ejection thus forming an ejection plume of material from the target that acts as a rocket to deflect the object. This is generally classified as laser ablation. DE-STARLITE uses conventional propellant for launch to LEO and then ion engines to propel the spacecraft from LEO to the near-Earth asteroid (NEA). During laser ablation, the asteroid itself provides the propellant source material; thus a very modest spacecraft can deflect an asteroid much larger than would be possible with a system of similar mission mass using ion beam deflection (IBD) or a gravity tractor. DE-STARLITE is capable of deflecting an Apophis-class (325 m diameter) asteroid with a 1- to 15-year targeting time (laser on time) depending on the system design. The mission fits within the rough mission parameters of the Asteroid Redirect Mission (ARM) program in terms of mass and size. DE-STARLITE also has much greater capability for planetary defense than current proposals and is readily scalable to match the threat. It can deflect all known threats with sufficient warning

DE-STARLITE: A Directed Energy Planetary Defense Mission

This paper presents the motivation behind and design of a directed energy planetary defense system that utilizes laser ablation of an asteroid to impart a deflecting force on the target. The proposed system is called DE-STARLITE for Directed Energy System for Targeting of Asteroids and ExploRation – LITE as it is a small, stand-on unit of a larger standoff DE-STAR system. Pursuant to the stand-on design, ion engines will propel the spacecraft from low-Earth orbit (LEO) to the near-Earth asteroid (NEA). During laser ablation, the asteroid itself becomes the propellant ; thus a very modest spacecraft can deflect an asteroid much larger than would be possible with a system of similar mission mass using ion beam deflection (IBD) or a gravity tractor. DE-STARLITE is capable of deflecting an Apophis-class (325 m diameter) asteroid with a 15-year targeting time. The mission fits within the rough mission parameters of the Asteroid Redirect Mission (ARM) program in terms of mass and size and has much greater capability for planetary defense than current proposals and is readily scalable to the threat. It can deflect all known threats with sufficient warning

Galactic foreground contribution to the BEAST CMB Anisotropy Maps

We report limits on the Galactic foreground emission contribution to the Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB anisotropy maps. We estimate the contribution from the cross-correlations between these maps and the foreground emission templates of an H${\alpha}$ map, a de-striped version of the Haslam et al. 408 MHz map, and a combined 100 $\mu$m IRAS/DIRBE map. Our analysis samples the BEAST $\sim10^\circ$ declination band into 24 one-hour (RA) wide sectors with $\sim7900$ pixels each, where we calculate: (a) the linear correlation coefficient between the anisotropy maps and the templates; (b) the coupling constants between the specific intensity units of the templates and the antenna temperature at the BEAST frequencies and (c) the individual foreground contributions to the BEAST anisotropy maps. The peak sector contributions of the contaminants in the Ka-band are of 56.5% free-free with a coupling constant of $8.3\pm0.4$ $\mu$K/R, and 67.4% dust with $45.0\pm2.0$ $\mu$K/(MJy/sr). In the Q-band the corresponding values are of 64.4% free-free with $4.1\pm0.2$ $\mu$K/R and 67.5% dust with $24.0\pm1.0$ $\mu$K/(MJy/sr). Using a lower limit of 10% in the relative uncertainty of the coupling constants, we can constrain the sector contributions of each contaminant in both maps to $< 20$% in 21 (free-free), 19 (dust) and 22 (synchrotron) sectors. At this level, all these sectors are found outside of the $\mid$b$\mid = 14.6^\circ$ region. By performing the same correlation analysis as a function of Galactic scale height, we conclude that the region within $b=\pm17.5^{\circ}$ should be removed from the BEAST maps for CMB studies in order to keep individual Galactic contributions below $\sim 1$% of the map's rms.Comment: 17 pages PostScript file. Better resolution figures can be found in the web page http://www.das.inpe.br/~alex/beast_foregrounds.html. Accepted for publication in the ApJ Suppl. Serie

Somatic Activating PIK3CA Mutations Cause Venous Malformation

Somatic mutations in TEK, the gene encoding endothelial cell tyrosine kinase receptor TIE2, cause more than half of sporadically occur- ring unifocal venous malformations (VMs). Here, we report that somatic mutations in PIK3CA, the gene encoding the catalytic p110a subunit of PI3K, cause 54% (27 out of 50) of VMs with no detected TEK mutation. The hotspot mutations c.1624G>A, c.1633G>A, and c.3140A>G (p.Glu542Lys, p.Glu545Lys, and p.His1047Arg), frequent in PIK3CA-associated cancers, overgrowth syndromes, and lymphatic malformation (LM), account for >92% of individuals who carry mutations. Like VM-causative mutations in TEK, the PIK3CA mutations cause chronic activation of AKT, dysregulation of certain important angiogenic factors, and abnormal endothelial cell morphology when expressed in human umbilical vein cells (HUVECs). The p110a-specific inhibitor BYL719 restores all abnormal phenotypes tested, in PIK3CA- as well as TEK mutant HUVECs, demonstrating that they operate via the same pathogenic path- ways. Nevertheless, significant genotype-phenotype correlations in lesion localization and histology are observed between individuals with mutations in PIK3CA versus TEK, pointing to gene-specific effect

A 31 Pixel Flared 100-GHz High-Gain Scalar Corrugated Non-bonded Platelet Antenna Array

Abstract-A compact 100-GHz corrugated platelet antenna array has been developed based on a corrugated feed design for the BEAST (Background Emission Anisotropy Scanning Telescope) optics. The antennas in the array result in a gain of 20 dB, and a bandwidth across the full range of W-band 75-110 GHz. The side lobes are down by about -25 dB, a requirement comparable to feed horns used for observation of the Cosmic Microwave Background. The design and fabrication presented in this paper is straightforward and inexpensive. A feature is that because the plates are not permanently bonded, the horn can be disassembled and modified to change its properties such as addition of flare plates or modified rib structures. Index Terms-corrugated feed, millimeter-waves, platelet horn, cosmic microwave background