Electron Beams

This paper presents applications in which Electron Beam Induced Deposition (EBID) is used to characterize, analyze, and fabricate, nanostructures and devices. High aspect ratio Cylindrical Ultra Sharp (CUS) Atomic Force Microscope (AFM) probe tips are grown on discarded AFM tips using EBID. AFM is done using these CUS probe tips and compared to standard commercially available AFM probes as a baseline. The use of EBID to deposit platinum nanodots on thin foils for use as a hard mask in the fabrication of Quantum Cellular Automata cell structures is also reported. Successful EDS analysis was performed on these nanodots in a conventional Scanning Electron Microscope (SEM) with a high spatial resolution normally found only in the Scanning Transmission Electron Microscope (STEM). These EDS results demonstrate the ability to capture pertinent material properties of nanostructures in a more manageable SEM, and therefore, forgo the necessary complexities associated with a standard STEM.

Molecular orientation dependences of the ionization energy (IE) and the electron affinity (EA) of diindenoperylene (DIP) films were studied by using ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPES). The molecular orientation was controlled by preparing the DIP films on graphite and SiO2 substrates. The threshold IE and EA of DIP thin films were determined to be 5.81 and 3.53 eV for the film of flat-lying DIP orientation, respectively, and 5.38 and 3.13 eV for the film of standing DIP orientation, respectively. The result indicates that the IE and EA for the flat-lying film are larger by 0.4 eV and the frontier orbital states shift away from the vacuum level compared to the standing film. This rigid energy shift is ascribed to a surface-electrostatic potential produced by the intramolecular polar bond (> C --H + ) for standing orientation and -electron tailing to vacuum for flat lying orientation.

The design and experimental study of a 35-GHz gyrotron-traveling-wave tube (gyro-TWT) amplifier operating in the circular TE 0 i mode at the fundamental cyclotron harmonic are presented. The interaction circuit in this experiment consisted of a new type of ceramic loading that provided the required loss for stable operation. A saturated peak power of 137 kW was measured at 34.1 GHz, corresponding to a saturated gain of 47.0 dB and an efficiency of 17%, with a -3-dB bandwidth of 1.11 GHz (3.3%). Peak output powers in the range of 102.1 to 148.6 kW with -3-dB bandwidths of 1.26 and 0.94 GHz, respectively, were measured by varying the operating parameters. The gyro-TWT was found to be zero-drive stable at these operating points, demonstrating that ceramic loading is a highly effective means of suppressing spurious oscillations in gyro-TWTs. This type of ceramic loading has the added advantage of being compatible with high average power operation.

We present the results of the differences observed between evaporated and sputtered backside metallization processes on silicon wafers: These two methods of fabricating metal layers and the activation of the backside semiconductor-metal contact follow different physical mechanisms. Differing crystalline structures of the metal layers can be observed and the thermal budget of the overall process of the wafer is affected in different ways. In this paper we describe these differences, provide a description of the known physical and mechanical mechanisms and propose some models. Additionally we report a few production issues and experiences.

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This paper considers the problem of designing electron guns using computer optimization techniques. Several different design parameters are manipulated while considering multiple design criteria including beam and gun properties. The optimization routines are described. Examples of guns designed using these techniques are presented. Future research is also described.

A precise lithographic model has always been a critical component for the technique of Optical Proximity Correction (OPC) since it was introduced a decade ago . As semiconductor manufacturing moves to 32nm and 22nm technology nodes with 193nm wafer immersion lithography, the demand for more accurate models is unprecedented to predict complex imaging phenomena at high numerical aperture (NA) with aggressive illumination conditions necessary for these nodes. An OPC model may comprise all the physical processing components from mask e-beam writing steps to final CDSEM measurement of the feature dimensions. In order to provide a precise model, it is desired that every component involved in the processing physics be accurately modeled using minimum metrology data. In the past years, much attention has been paid to studying mask 3-D effects, mask writing limitations, laser spectrum profile, lens pupil polarization/apodization, source shape characterization, stage vibration, and so on. However, relatively fewer studies have been devoted to modeling of the development process of resist film though it is an essential processing step that cannot be neglected. Instead, threshold models are commonly used to approximate resist development behavior. While resist models capable of simulating development path are widely used in many commercial lithography simulators, the lack of this component in current OPC modeling lies in the fact that direct adoption of those development models into OPC modeling compromises its capability of full chip simulation. In this work, we have successfully incorporated a photoresist development model into production OPC modeling software without sacrificing its full chip capability. The resist film development behavior is simulated in the model to incorporate observed complex resist phenomena such as surface inhibition, developer mass transport, HMDS poisoning, development contrast, etc. The necessary parameters are calibrated using metrology data in the same way that current model calibration is done. The method is validated with a rigorous lithography process simulation tool which is based on physical models to simulate and predict effects during the resist PEB and development process. Furthermore, an experimental lithographic process was modeled using this new methodology, showing significant improvement in modeling accuracy in compassion to a traditional model. Layout correction test has shown that the new model form is equivalent to traditional model forms in terms of correction convergence and speed.

Extreme Ultraviolet Lithography (EUVL) masks have residual stress induced by several thin films on low thermal expansion material (LTEM) substrates. The stressed thin films finally result in convex out-of-plane displacement (OPD) of several 100s of nm on the pattern side of the mask. Since EUVL masks are chucked on EUVL scanners differently from on e-beam writer, the mask pattern placement errors (PPE) are necessary to be corrected for to reduce overlay errors. In this paper, experimental results of pattern placement error correction using standard chrome on glass (COG) plate will be discussed together with simulations. Excellent agreement with simple bending theory is obtained. Suitability of the model to compensate for other EUVL-related PPEs due to mask non-flatness will be discussed.

In this paper, we propose and evaluate the performance of a practical 270 • bent-axial-type electron gun, in which focusing is bidirectional through an axial magnetic field. Such an electron gun has two advantages: 1) a high-voltage cathode assembly placed in a geometrical shadow region of the emerging vapor and 2) a compact electron beam (e-beam) spot with circular symmetry that results in high power density. It is also shown that the position of the e-beam spot on the target is controllable along any direction without compromising the compactness and circular symmetry of the e-beam spot just like a straight-axial-type electron gun, but not typically possible for conventional 270 • bent-transverse-type electron guns.

Plasma-assisted slow-wave oscillators (pasotrons) are unique sources of microwave radiation, in which the beam propagation in the absence of external magnetic fields is provided by the ion focusing and the electron interaction with the RF field is essentially two-dimensional. This paper overviews the results obtained in the last several years and presents recent accomplishments in the theory and experimental performance of the pasotron. In particular, the 50% efficient operation at the 0.5-MW power level and more than 30% efficient operation at more than a 1-MW level are reported. Theoretical results of the analysis of nonstationary self-consistent processes in the beam focusing and transport agree with PIC simulations. The paper also contains the first results of the noise measurements in the pasotron. The paper is focused at describing the progress in the field, and explaining the interesting physical effects and improvements in the device performance without going into details of either the theoretical formalism or experimental parameters.

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An overview is given of the physics issues relevant to the plasma wakefield accelerator, the plasma beat-wave accelerator, the laser wakefield accelerator, including the self-modulated regime, and wakefield accelerators driven by multiple electron or laser pulses. Basic properties of linear and nonlinear plasma waves are discussed, as well as the trapping and acceleration of electrons in the plasma wave. Formulas are presented for the accelerating field and the energy gain in the various accelerator configurations. The propagation of the drive electron or laser beams is discussed, including limitations imposed by key instabilities and methods for optically guiding laser pulses. Recent experimental results are summarized.

A medium power, repetitive electron beam generator has been designed and fabricated to enable the evaluation of a novel, large-area electron-transparent window. The test stand was developed to demonstrate the electron transparency and the thermal response of the window to an electron beam. The electron beam generator design is described in this article, and focuses on the electrical driver circuit and the electron gun, including external electron beam focusing elements.

Electron beam lithography (EBL) patterning of poly(methylmethacrylate) (PMMA) is a versatile tool for defining molecular structures on the sub-10-nm scale. We demonstrate lithographic resolution to about 5 nm using a cold-development technique. Liftoff of sub-10-nm Au nanoparticles and metal lines proves that cold development completely clears the PMMA residue on the exposed areas. Molecular liftoff is performed to pattern DNA rafts with high fidelity at linewidths of about 100 nm. High-resolution EBL and molecular liftoff can be applied to pattern Creutz-Taube molecules on the scale of a few nanometers for quantum-dot cellular automata.

We report dynamic and microscopic investigations of electrical stress induced defects in a high-k/metal gate stack by electron beam induced current (EBIC). The correlation between dielectric breakdown and EBIC sites are reported. A systematic study was performed on pre-existing and electrical stress induced defects. These defects are successfully visualized. The origin of pre-existing defects is discussed, comparing different gate electrodes and their temperature-dependence.

Backscattering coefficient η of monoenergetic electrons impinging normally on the thick target has been found to be expressed by an empirical equation of the form η=a1/[1+a2τ^(a3)], where τ is the incident kinetic energy in units of the rest energy of the electron, and the parameters ai (i = 1, 2, 3) are given by simple functions of target atomic number Z. Values of eight constants to express ai have been determined by least-squares fit to a total of 615 experimental points reported in 20 references. This equation is valid for Z≥6 in the energy region from about 50 keV to the highest energy of the existing experimental data (22 MeV), and the rms deviation of the experimental data from the equation is about 7%.

Lactating Holstein cows, averaging 80 d in milk, were used to examine effects of exogenous bovine somatotropin (bST) on oviductal and uterine genes encoding components of the insulin-like growth factor (IGF) system. About 12 h before expected ovulation in an Ovsynch protocol, cows were assigned randomly to receive bST (500 mg; n = 11) or serve as untreated controls (n = 10). Cows that ovulated (n = 9 bST, 8 control) were divided within treatment to be sacrificed on d 3 or 7 postovulation. Samples of oviductal and intercaruncular endometrial tissue from oviducts and uterine horns ipsilateral to the corpus luteum (CL) were collected and immediately frozen at − 80°C for subsequent mRNA analyses. Northern blots revealed mRNAs for IGF-II, IGF-binding protein-2 (IGFBP-2), and IGFBP-3 in all oviductal and endometrial tissues. Significant amounts of IGF-I and growth hormone receptor-1A (GHR-1A) mRNAs were detected in uteri but not in oviducts. The bST treatment had no effect on amount of IGF-I mRNA transcript in uterine endometrium. The mRNA encoding IGF-II was induced by bST in oviducts collected on both d 3 and 7 but was down-regulated in endometrium on d 7. Transcript of IGFBP-2 mRNA was greater in endometrial than oviductal tissues and did not differ between treatments. Both oviductal and endometrial IGFBP-3 mRNA concentrations increased between d 3 and 7 postovulation, with a tendency for greater endometrial IGFBP-3 mRNA in bST-treated cows on d 7. On d 7, concentrations of endometrial GHR-1A mRNA were 30% lower in bST-treated cows. Results indicate complex and tissue-specific regulation of the uterine IGF system components by exogenous bST. Some of

This paper presents a large-signal analysis of a klystron amplifier. It is used lagrangian approach and disk model theory in a one-dimensional analysis with emphasis in the effects of the presence of the space-charge force. After showing the result in the free space without considering the space-charge force, is added one that consider this force based on the Green's function approach. Finally, some results for a cylindrical electron beam inside a circular waveguide are shown.

In the development of powerful gyrotrons capable of long-pulse or continuous wave operation the cardinal problem is to provide stable, single-mode highly efficient operation at the desired mode with an acceptable level of ohmic losses in the resonator walls. In the present paper the selective properties of various coaxial resonators as well as ohmic losses of the microwave power in outer and inner conductors are considered. The start-up scenario in powerful gyrotrons is discussed. The results of numerical simulations of a 1 MW, 280-CHz coaxial gyrotron are presented which demonstrate that successive excitation of a number of modes during the voltage rise may not hinder the stable operation of the desired mode on the top of the voltage pulse. An electronic efficiency of 48% is predicted.

A new module, SYNRAD, has been added to the MOLFLOW [l] software package, allowing the Montecarlo (MC) simulation of synchrotron radiation (SR) emission. The geometrical three-dimensional (3D) distribution of the photons, power and energy, and spectra can be calculated. A model of the vacuum chamber is generated, and the profiles of SR-induced desorption are obtained by means of SYNRAD. These desorption profiles are then embedded in the vacuum chamber model and the MC program for the calculation of UHV molecular flow is used for obtaining relevant quantities such as, among others, pressure profiles, pumping speed efficiencies and conductances. Results of the application of SYNRAD and MOLFLOW, and comparison with some published data will be given.

K nowledge of the structure of biological specimens is critical to understanding their functions at all scales [1] and is crucial in biosciences to complement biochemical studies. Electron microscopy (EM) enables the investigation of the structure of biological specimens over a wide range of sizes, from cellular structures to single macromolecules, providing information at low/medium/high resolution [2], [3] and, in some cases, at atomic resolution . The combination of EM with other high-resolution approaches, e.g., X-ray crystallography or nuclear magnetic resonance (NMR), allows integration of the structural information gathered at multiple levels of the biological complexity into a common framework, which is expected to provide a comprehensive description of the cellular function in molecular detail .

A theory is developed for a free-electron laser ͑FEL͒ with a three-dimensional helical wiggler and ion-channel guiding. The relativistic equation of motion for a single electron in the combined wiggler and ion-channel fields is solved in the rotating wiggler frame. With the aid of the conservation of energy, equations for the axial velocity and the ⌽ function ͑which determines the rate of change of axial velocity with energy͒ are studied numerically. An analysis of the electromagnetic radiation copropagating with the electron beam in the FEL interaction region is also presented. The gain formula is derived and calculations indicate that the gain of the realizable wiggler is considerably greater than the gain of the idealized one, and the gain enhancement increases with increasing wiggler magnetic field. It is shown that the gain for group-I orbits is positive, while for group-II orbits, the gain is negative in the negative mass regime ͑i.e., ⌽Ͻ0͒ and positive in the positive mass regime.

An automated technique for the mapping of nanocrystal phases and orientations in a transmission electron microscope is described. It is primarily based on the projected reciprocal lattice geometry that is extracted from electron diffraction spot patterns. Precession electron diffraction patterns are especially useful for this purpose. The required hardware allows for a scanning-precession movement of the primary electron beam on the crystalline sample and can be interfaced to any older or newer mid-voltage transmission electron microscope (TEM). Experimentally obtained crystal phase and orientation maps are shown for a variety of samples. Comprehensive commercial and open-access crystallographic databases may be used in support of the nanocrystal phase identification process and are briefly mentioned.

A FEBIP-(Focused Electron Beam Induced Processing )-System is used to develop a novel miniaturized tunable, portable THz source for 0.1 to 6 THz. The control voltage with the high frequency is generated using a miniaturized Dynatron oscillator. An oscillator is connected to the anode of the Dynatron triode which modulates the anode voltage due to self excited oscillations. The modulated anode voltage is used to control the emission of two miniaturized electron beams, which emit in phase shifted powerful electron pulses in coaxial and opposite direction. As the charges flow in an antenna wire the free flying electron beam pulses emit dipole radiation into a resonator which is adapted in its dimensions to the expected wavelength of the emitted dipole radiation. Like in Klystrons up to 47 % of the power in the free beams is emitted into the THz radiation. Unlike as in transmitter antennas the oscillation charges are flying here in free space. This avoids additional power loss by Joules heating of the resistive wire. We expect a source power of up to 0.1 Watt for such a sources.

In support of the High Average Power Laser (HAPL) project the Electra Laser, a KrF Gas Laser system is being developed at NRL. The laser uses high voltage (500-800 keV), high current (100-500 kA), short pulse (100-600 ns) electron beams to pump the 0.14 MPa (20 psi) pressurized KrF gas cell, which is separated from the vacuum region by a 25 m-thick stainless steel foil, the Hibachi Foil. The foil is made of SUS304, operates between 180 C and 450 C, and has typical dimensions of about 0.3 m 1.0 m. The laser pulses at up to 5 Hz, and the foil is subjected to repetitive thermal and mechanical stresses. In typical experiments, the foil lasts 1000-20,000 shots before suffering a catastrophic failure. In an attempt to improve foil performance a variety of design modifications are being considered along with changes in foil material. Earlier Hibachi foil designs used flat foils resting on 0.3 m long square watercooled supporting ribs (1 cm wide). There is a 3.4 cm gap between ribs.. Advanced Hibachi foil concepts are under development using a scalloped foil design. In this paper we report on the comparative thermo-mechanical analysis between flat and scalloped foil geometries. It is demonstrated that the scalloped design reduces stresses to within yield limits of the stainless steel material.

The broad development of the micro-and nano-technologies in the past few years increased the need of techniques capable of fabricating sub-micron structures with arbitrary surface profiles. Out of the several fabrication approaches (HEBS lithography, laser writing, etc.) the electron beam writing stands out as the one capable of the highest resolution, superior alignment accuracy and very small surface roughness. These characteristics make the technique greatly applicable in the fields of photonics and micro-opto-electro-mechanical-systems (MOEMS). Here we describe the specificity of fabricating 3D diffractive micro-and nano-optical elements using Leica EBPG 5000+ electron beam system. Parameters like speed of writing, dose accumulation, pattern writing specifics, etc. affect greatly the electronbeam resist properties and the desired 3D profile. We present data that can be used to better understand the different dependencies and therefore achieve better profile and surface roughness management. The results can be useful in future developments in the areas of integrated photonic circuits and MOEMS.

A non-perturbing electron beam diagnostic system for measuring the charge distribution of an ion beam is developed for Heavy Ion Fusion (HIF) beam physics studies. Conventional diagnostics require temporary insertion of sensors into the beam, but such diagnostics stop the beam, or significantly alter its properties. In this diagnostic a low energy, low current electron beam is swept transversely across

Much attention is currently being paid to the materials and processes that allow one to directly write or to imprint waveguiding structures and/or diffractive elements for optical integrated circuits by exposure from a source of photons, electrons or ions. Here a brief overview of the results achieved in our laboratories is presented, concerning the fabrication and characterization of optical guiding structures based on different materials and exposure techniques. These approaches include: electron and ion beam writing of waveguides in (poly)-crystalline lithium fluoride, uv-laser printing of waveguides and gratings in photorefractive glass thin films, and fs-laser writing in tellurite glasses. Properties and perspectives of these approaches are also discussed.

We report on the fabrication and operation of a circular grating coupled, surface-emitting distributed Bragg reflector (DBR) laser with an integrated focusing outcoupler. Electron beam lithography and reactive ion beam etching were used to fabricate the laser with a first-order resonant grating for optical feedback and a separate detuned, chirped second-order grating for outcoupling and focusing the beam.

REBL (Reflective Electron Beam Lithography) is being developed for high throughput electron beam direct write maskless lithography. The system is specifically targeting 5 to 7 wafer levels per hour throughput on average at the 45 nm node, with extendibility to the 32 nm node and beyond. REBL incorporates a number of novel technologies to generate and expose lithographic patterns at estimated throughputs considerably higher than electron beam lithography has been able to achieve as yet. A patented reflective electron optic concept enables the unique approach utilized for the Digital Pattern Generator (DPG). The DPG is a CMOS ASIC chip with an array of small, independently controllable cells or pixels, which act as an array of electron mirrors. In this way, the system is capable of generating the pattern to be written using massively parallel exposure by ~1 million beams at extremely high data rates (~ 1Tbps). A rotary stage concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG to achieve the capability of high throughput for sparse pattern wafer levels. The exposure method utilized by the DPG was emulated on a Vistec VB-6 in order to validate the gray level exposure method used in REBL. Results of these exposure tests are discussed.

This paper presents an overview of key nanoscale manufacturing technologies, and qualitatively examines their fundamental process requirements with respect to energy demand. The processes requirements are related to semiconductor manufacturing, where applicable, and gaps in our understanding of these processes on the production scale are identified as goals for the research community. Finally, the paper proposes a framework for the systematic analysis of energy use in nanoscale manufacturing processes

Liquid-phase polymerisation of acrylamide-acrylic acid to form polyelectrolytes used in wastewater cleaning was examined using accelerated electron beam and microwave irradiation methods. Polymerisation was carried out in aqueous solutions at temperatures ∼60 • C. Monomers total concentration was established at 40% (36% acrylamide and 4% acrylic acid). Only using the features of simultaneous radiation-induction and microwave heating can result in the formation of linear polymer chains with good water solubility and low residual monomer concentration. The flocculation capacity of the obtained polymers was tested using two wastewaters, one sampled from a slaughterhouse and the other from a vegetable oil plant. Quality indicators such as total suspended matters (TSM), chemical oxygen demand (COD), biological oxygen demand (BOD) and fat, oils and grease (FOG) were measured before and after the treatment with polymeric flocculants and compared with the results obtained in classical treatment with Al 2 (SO 4 ) 3 . It was found that the combined treatment with polymers and Al 2 (SO 4 ) 3 increases the degree of purification of both wastewaters up to 99%.

The synchrotron radiation emitted from the NSLS VUV ring is found to contain significant spectral structure at long wavelengths (λ > 0.5mm), suggesting multiple beam interference effects. A predominant pattern occurs as a result of direct radiation interfering with radiation reflected from the curved outer wall of the electron beam dipole chambers. This structure appears for both normal incoherent synchrotron radiation emission and coherent emission, the latter resulting from an instability-driven density modulation within the electron bunch

The minimum lithographic feature size for microelectronic fabrication continues to shrink, and resist properties are beginning to dominate the achievable resolution. There is a strong need for a high resolution, high sensitivity resist for future nodes that is not met by conventional polymeric resists at this time. Molecular resists, such as fullerene derivatives have the potential for lower LWR and improved resolution, but have typically been insufficiently sensitive to irradiation. Here we present a fullerene based three component chemically amplified resist system with high resolution and sensitivity, and wide process latitude. The sensitivity of this resist is between 5 and 10 µC/cm2 at 20 keV for various combinations of post application bake and post exposure bake conditions. Using 30 keV electron beam exposure, sparse patterns with 12 nm resolution were demonstrated, at a line dose of 300 pC/cm, whilst dense patterns with half-pitch 20 nm were achieved at 200 pC/cm. The LWR for the densely patterned resist (measured at 20 nm half pitch) is ~ 4.4 nm, whilst for the 12 nm sparse feature the measured LWR is ~ 2.5 nm. The etch durability is comparable with commercial novolac resists

Linear accelerators driving Free Electron Lasers (FELs), such as the Free Electron Laser in Hamburg (FLASH) or the X-ray Free Electron Laser (XFEL), require sophisticated Low Level Radio Frequency (LLRF) control systems. The controller of the LLRF system should stabilize the phase and amplitude of the field in accelerating modules below 0.02% of the amplitude and 0.01 degree for phase tolerances to produce an ultra stable electron beam that meets the required conditions for Self-Amplified Spontaneous Emission (SASE). Since the LLRF system for the XFEL must be in operation for the next 20 years, it should be reliable, reproducible and upgradeable. Having in mind all requirements of the LLRF control system, the Advanced Telecommunications Computing Architecture (ATCA) has been chosen to build a prototype of the LLRF system for the FLASH accelerator that is able to supervise 32 cavities of one RF station. The LLRF controller takes advantage of features offered by the ATCA standard. The LLRF system consists of a few ATCA carrier blades, Rear Transition Modules (RTM) and several Advanced Mezzanine Cards (AMCs) that provide all necessary digital and analog hardware components. The distributed hardware of the LLRF system requires a number of communication links that should provide different latencies, bandwidths and protocols. The paper presents the general view of the ATCA-based LLRF system, discusses requirements and proposes an application for various interfaces and protocols in the distributed LLRF control system.

The Eros facility at AWE was designed to simulate radiation effects using a large area diode driven by a low impedance Blumlein charged by a Marx generator. Recent interest at AWE to develop low impedance, high current pinched diodes, have lead to a ...

The morphology of poly(aryl-ether-ether-ketone) (PEEK) has been studied using optical microscopy (at room temperature and at elevated temperatures), small-angle light scattering (H v and V v ), transmission electron microscopy (bright field, dark field, and selected area electron ...

The first stage bunch compressor in the NLC injector complex compresses the e+/e-beams from a bunch length of 5 mm rms to 0.5 mm rms at the beam energy of 2 GeV. To obtain this compression ratio, the compressor rf section operates with an rf frequency of 1.4 GHz and a voltage of about 140 MV while a magnetic wiggler is used to generate an R 56 = 0.5 m. The bunch compressor is designed to operate with a beam from the damping ring that has a bunch spacing slew of 20ps across the bunch train due to the transient loading in the damping rings. The compressor RF section is required to produce a specific energy profile along the bunch train so that the bunch spacing can be corrected in the compressor bending section. Further, the 1-amp beam heavily loads the compressor linac and beam loading compensation is essential to prevent a phase variation along the bunch train in the downstream linacs. In this paper, we will present simulation results of the beam loading compensation using a ∆T scheme assuming various initial bunch spacing arrangements. We will study the impact of the different compressor energy profiles on the beam energy, energy spread, and bunch length at the IP.