arXiv:physics/0108005v2 [physics.gen-ph] 30 Aug 2001 Impulse Gravity Generator Based on Charged Superconductor with Composite Crystal Evgeny Podkletnov , Giovanni Modanese Moscow Chemical Scientific Research Centre 113452 Moscow - Russia E-mail:
[email protected] California Institute for Physics and Astrophysics 366 Cambridge Ave., Palo Alto, CA 94306 University of Bolzano Industrial Engineering Via Sernesi 1, 39100 Bolzano, Italy E-mail:
[email protected] The detection of apparent anomalous forces in the vicinity of high-T ductors under non equilibrium conditions has stimulated anexperimental research in which the operating parameters of the experiment have been pushed to values higher than those employed in previous attempts. The results confirm the existence of an unexpected physical interaction. An apparatus has been constructed and tested in which the superconductor is subjected to peak currents in excess of 10 A, surface potentials in excess of 1MV, trapped magnetic field up to 1T, and temperature down to 40K. In order to produce the required currents a high voltage discharge technique has been employed. Discharges originating from asuperconducting ceramic electrode are accompanied by the emission of radiation which propagates in a focused beam without noticeable attenuation through different materials and exerts a short repulsive force on small movable objects along the propagation axis. Within the measurement error (5 to 7 %) the impulse is proportional to the mass of the objects and independent on their composition. It therefore resembles a gravitational impulse. The observed phenomenon appears to be absolutely new and unprecedented in the literature. It cannot be understood in the framework of general relativity. A theory is proposed which combines a quantum gravity approach with anomalous vacuum fluctuations. 1 Introduction2 2 Experimental2 2.2 Superconducting emitter, fabrication methods . . . . . . .. . . . . . . . . 4 2.3 Organization of the discharge and measurements of the effect. . . . . . . . 6 3 Results7 4 Discussion10 4.1 A possible theoretical explanation. Basic concepts. . .. . . . . . . . . . . 12 4.2 Possible interpretation of the gravitational-like impulse at the discharge . . 19 4.3 Known effects which could be connected to the observed phenomenon. . . . 21 5 Conclusions26 1 Introduction Experiments showing possible anomalous forces between high-T ceramic superconductors under non equilibrium conditions and test objects have beenreported by several inves- tigators since 1992 [1, 2, 3, 4, 5]. The observed phenomenology was difficult to explain and has been attributed to a so called gravity modification, because the reported effects mimic well the properties of the gravitational interaction, although their nature has never been clearly understood. In fact several alternative explanations of these results have been proposed [6, 7, 8, 9, 42] in the attempt to bring the observed anomalies into the realm of known effects. Because of the great importance of any possible technical application of the reported effects, research activities have started in many laboratories since the first observation of the phenomenon [1]. Our recent research work focused on the improvement of the structure of the high-T ceramic superconductors which have demonstrated capabilities of creating anomalous forces. Moreover a high-voltage discharge apparatus has been designed and constructed in order to easily reach those non equilibrium electromagnetic conditions that seem required to produce the force effects in HTCs. The results described in this report should be regarded as preliminary. An improved version of the experiment is currently being planned. Nevertheless, the body of results, as well as the complexity of the experimental procedures and ofthe theoretical interpretation are such that a detailed description and diffusion could not be further delayed. All mea- surements were done by E. Podkletnov in Moscow, while G. Modanese provided theoretical 2 Experimental 2.1 General description of the installation The initial variant of the experimental set-up was based on ahigh-voltage generator placed in a closed cylinder chamber with a controlled gas atmosphere, as shown in Fig. 1. Two metal spheres inside the chamber were supported by hollow ceramic insulators and had electrical connections that allowed to organize a discharge between them, with voltage up to 500kV. One of the spheres had a thin superconducting coating ofY Ba obtained by plasma spraying using a Plasmatech 3000S installation. This sphere could be charged to high voltage using a high voltage generator similar to that of Van de Graaf. The second sphere could be moved along the axis of the chamber, the distance between the spheres varying from 250 to 2000mm. Spheres with a diameter from 250 to 500mm were used in the experiment. It was possible to fill the chamber with helium vapours or to create rough vacuum using a rotary pump. The walls of the chamber were made of non- conducting plastic composite material, with a big quartz glass window along one of the walls which allowed to observe the shape, the trajectory andthe colour of the discharge. In order to protect the environment and the computer networkfrom static electricity and powerful electromagnetic pulses, the chamber could be shielded by a Faraday cage with cell dimensions of 2.02.0cmand a rubber-plastic film material absorbing ultra high frequency (UHF) radiation. The superconducting sphere was kept at a temperature between 40 and 80K, which was achieved by injecting liquid helium or liquid nitrogen through a quartz tube inside the volume of the superconducting sphere before the charging began. The inside volume of the chamber was evacuated or filled with helium in order to avoid the condensation of moisture and different gases on the superconducting sphere. The temperature of the superconductor was measured using a standard thermocouple for low temperature measurements and was typically around 55-60K. Given the good heat conductivity of the superconductor, we estimated that the temperature difference in the ceramic didnot exceed 1K. An improved variant of the discharge chamber is shown in Fig.2. The charged electrode was changed to a toroid attached to a metal plate and a superconducting emitter which had the shape of a disk with round corners. The non-superconducting part of the emitter was fixed to a metal plate using metal Indium or Woodsmetal, the superconducting part of the emitter faced the opposite electrode. The secondelectrode was a metal toroid of smaller diameter, connected to a target. The target was a metal disk with the diameter of 100mmand the height of 15mm. The target was attached to a metal plate welded to the toroid. This improved design of the generator was able to create a well-formed discharge between the emitter and the target, still the trajectory wasnot always repeatable and it was difficult to maintain constant values of current and voltage. The chamber was also not rigid enough to obtain high vacuum and some moisture was condensing on the emitter, damaging the superconducting material and affecting the discharge characteristics. The large distance between the electrodes also caused considerable dissipation of energy during discharge. In order to improve the efficiency of operation, the measuring system and the reproducibility of the discharge, an entirely new design ofthe vacuum chamber and the charging system was created. The final variant of the discharge chamber is presented in Fig. 3 (the apparatus is shown in a vertical position though actually it is situated parallel to the floor). This set-up allowed to reduce the dimensions of the installation and to increase the efficiency of the process. The chamber has the form of a cylinder with the approximate diameter of 1m and the length of 1.5mand is made of quartz glass. The chamber has two connecting sections with flanges which allow to change the emitter easily. The design permits to create high vacuum inside or to fill the whole volume with any gas that is required. The distance of the discharge has been decreased considerably giving the possibility to reduce energy dissipation and to organize the discharge in a betterway. The distance between the electrodes can vary from 0.15 to 0.40min order to find the optimum length for each type of the emitter. The discharge can be concentrated on a smaller target area using a big solenoid with the diameter of 1.05mthat is wound around the chamber using copper wire with the diameter of 0.5cm. The magnetic flux density is 0.9T. A small solenoid is also wound around the emitter (Fig. 3) so that the magnetic field can be frozen inside a superconductor when it is cooled down below the critical temperature. The refrigeration system for the superconducting emitter provides a sufficient amount of liquid nitrogen or liquid helium for the long-term operation and the losses of gas due to evaporation are minimized because of the high vacuum insidethe chamber and thus of a better thermal insulation. A photodiode is placed on the transparent wall of the chamberand is connected to an oscilloscope, in order to provide information on the light parameters of the discharge. Given the low pressure and the high applied voltage, emission of X-rays from the metallic electrode cannot be excluded, but the short duration of the discharge makes their detection difficult. Use of a Geiger counter and of X-rays sensitive photographic plates did not yield any clear signature of X-rays. A precise measurement of the voltage of the discharge is achieved using a capacitive sensor that is connected to an oscilloscope with a memory option as shown in the upper part of Fig. 3. Electrical current measurements are carriedout using a Rogowski belt, which is a single loop of a coaxial cable placed around the target electrode and connected to the oscilloscope. The old fashioned Van de Graaf generator used in the previousstage of this work was replaced by a high voltage pulse generator as shown in Fig. 4. This pulse generator is executed according to the scheme of Arkadjev-Marx and consists of twenty capacitors (25nFeach) connected in parallel and charged to a voltage up to 50-100kVusing a high voltage transformer and a diode bridge. The capacitors are separated by resistive elements of about 100k. The scheme allows to charge the capacitors up to the neededvoltage and then to change the connection from a parallel to a serial one. The required voltage is achieved by changing the length of the air gap between the contact spheres C and D. A syncro pulse is then sent to the contacts C and D which causes an overall discharge and serial connection of the capacitors and provides a powerfulimpulse up to 2MVwhich is sent to the discharge chamber. The use of such an impulse generator allows for a precisely controlled voltage, much shorter charging time and good reproducibility of the process. 2.2 Superconducting emitter, fabrication methods The superconducting emitter has the shape of a disk with the diameter of 80-120mm and the thickness of 7-15mm. This disk consists of two layers: a superconducting layer with chemical compositionY Ba (containing small amounts ofCeandAg) and a normal conducting layer with chemical compositionY representsCe,Pr,Sm,Pm,Tbor other rare earth elements. The materials of both layers were synthesized using a solid state reaction under low oxygen pressure (stage 1), then the powder was subjected to a melt texture growth (MTG) procedure (stage 2). Dense material after MTG was crushed, ground and put through sieves in order to separate the particles with the required size. A bi-layered disk was prepared by powder compaction in a stainless steel die and sintering using seeded oxygen controlled melt texture growth (OCMTG) (stage 3). For the emitters with the diameter of 120mmusual sintering was applied instead of seeded OCMTG (stage 4). After mechanicaltreatment the ceramic emitter was attached to the surface of the cooling tank in thedischarge chamber using Indium based alloy. Stage 1 -Micron-size powders ofY andCuO,BaCO were mixed in alcohol for 2 hours, then dried and put in zirconia boats in a tube furnace for heat treatment. The mixture of powders was heated to 830 Cand kept at this temperature for 8 hours at oxygen partial pressure of 2.710 Pa(or 2-4mBar) according to [10, 11]. The material of the normal conducting layer was sintered in a similar way. Stage 2 -Micron-size powder ofY Ba was pressed into pellets using a metal die and low pressure. The pellets were heated in air to 1050 Cper hour) then cooled to 1010 Cper hour) then cooled to 960 Cper hour) then cooled to room temperature (100 Cper hour) according to a standard MTG technique [12, 13]. The quantity of 211 phase during heating was considerably reduced and the temperature was changed correspondingly.ReBa was also prepared using MTG, but the temperature was slightly changed according to the properties of the corresponding rare earth oxide. Stage 3 -Bulk material after MTG processing was crushed and ground ina ball mill. The particles with the size less than 30mwere used for both layers of the ceramic disk. The particles were mixed with polyvinyl alcohol binder. The material of the first layer was put into a die, flattened and then the material of thesecond layer was placed over it. The disk was formed using a pressure of 50MPa. The single crystal seeds ofSm123 (about 1mm ) were placed on the surface of the bi-layered disk so that thedistance between them was about 15mmand the disk was subjected to a OCMTG treatment in 1% oxygen atmosphere. The growth kinetics of YBCO superconductor were controlled during isothermal melt texturing. A modified melt texturingprocess was applied, where instead of slow cooling following melting, isothermal holdwas employed in the temperature range where the growth is isotropic. By this modification, the time required to texture the disk was reduced to 7 hours which is about 10 times faster thana typical slow cooling melt texturing process. The crystallization depth was controlled by applying the corresponding temperature and time parameters. CubicSm123 seeds were obtained using the nucleation and growth procedure as described in [16, 17]. A thin layer ofthe material was removed from the top surface of the disk to a depth of 0.3mmand the edges of the upper surface were rounded using diamond tools. Stage 4 -For the emitters with the diameter of 120mmit is technically difficult to apply seeded MTG method, therefore normal sintering was carried out. Bulk material after MTG processing (after stage 2) was crushed and sieved and the following size particles were used for both layers of the ceramic disk, the amount is given in weight percent: The particles were mixed according to the ratio listed aboveusing polyvinyl alcohol as a binder. The material of the first layer was put into a die, flattened and the material of the second layer was placed over it. The disk was formed using the pressure of 120 MPaand sintered in oxygen at 930 Cfor 12 hours followed by slow cooling down to room temperature. The edges of the upper surface were rounded using diamond tools. X-ray diffraction, transition temperature, electrical conductivity and critical current density were measured for both layers of various emitters using standard techniques. 2.3 Organization of the discharge and measurements of the ef- The discharge chamber is evacuated to 1.0Pausing first a rotary pump and then a cryo- genic pump. When this level of vacuum is reached, liquid nitrogen is pumped into a tank inside the chamber that contacts the superconducting emitter. Simultaneously a current is sent to the solenoid that is wound around the emitter, in order to create a magnetic flux inside the superconducting ceramic disk. When the temperature of the disk falls below the transition temperature (usually 90K) the solenoid is switched off. The experiment can be carried out at liquid nitrogen temperatures or at liquid helium temperatures. If low temperatures are required, the tank is filled with liquidhelium and in that case the temperature of the emitter reaches 40-50K. The high voltage pulse generator is switched on and the capacitors are charged to the required voltage. It takes about 120sto charge the capacitors. A syncro pulse is sent to a pair of small metal spheres marked as C and D in Fig. 5. A discharge with voltage up to 2MVoccurs between the emitter and the target. Half a second before the discharge, a short pulse of direct current is sent for 1sto the big solenoid that is wound around the chamber, in order to concentrate the discharge and to direct it to the same area on the target electrode. This pulse lasts for only 1snot to cause the overheating of the big The effects are measured along the projection of the axis linewhich connects the center of the emitter with the center of the target. Laser pointers were used to define the projection of the axis line and impulse sensitive devices were situated at the distance of 6 mand 150mfrom the installation (in another building across the area). Normal pendulums were used to measure the pulses of gravity radiation coming from the emitter. The pendulums consisted of spheres of differentmaterials hanging on cotton strings inside glass cylinders under vacuum. One end of the string was fixed to the upper cap of the cylinder, the other one was connected to a sphere. The spheres had typically a diameter from 10 to 25mmand had a small pointer in the bottom part. A ruler was placed in the bottom part of the cylinder, 2mmlower than the pointer. The deflection was observed visually using a ruler inside the cylinder (Fig. 5). The length of the string was typically 800mm, though we also used a string 500mmlong. Various materials were used as spheres in the pendulum: metal, glass, ceramics, wood, rubber, plastic. The tests were carried out when the installation was covered with a Faraday cage and UHF radiation absorbing material and also without them. The installation was separated from the impulse measuring devices situated 6maway by a brick wall of 0.3mthickness and a list of steel with the dimensions 1m1.2m0.025m. The measuring systems that were situated 150maway were additionally shielded by a brick wall of 0.8mthickness. In order to define some other characteristics of the gravity impulse - in particular its frequency spectrum - a condenser microphone was placed along the impact line just after the glass cylinders. The microphone was connected to acomputer and placed in a plastic spherical box filled with porous rubber. The microphone was first oriented with a membrane facing the direction of the discharge, then it was turned 22.5 degrees to the left, then 45 degrees to the left, then 67.5 degrees and finally 90 degrees. Several discharges were recorded in all these positions at equal discharge voltage. 3 Results Several unexpected phenomena were observed during the experiments. The discharge in the installation corresponding to the initial set-up (Fig.1) at room temperature in the voltage range from 100kVto 450kVwas similar to a discharge with non-coated metal spheres and consisted of a single spark between the closest points on the spheres. When the superconductor coated sphere was cooled down below the transition temperature, the shape of the discharge changed in such a way that it did not form a direct spark between two spheres, but the sparks appeared from many points on the